Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Objective. Retinal prostheses have been developed to restore vision in blind patients suffering from diseases like retinitis pigmentosa. Approach. A new type of retinal prosthesis called the Okayama University-type retinal prosthesis (OUReP) was developed by chemically coupling photoelectric dyes to a polyethylene film surface. The prosthesis works by passively generating an electric potential when stimulated by light. However, the neurophysiological mechanism of how OUReP stimulates the degenerated retina is unknown. Main results. Here, we explore how the OUReP affects retinal tissues using a finite element model to solve for the potential inside the tissue and an active Hodgkin-Huxley model based on rat vision to predict the corresponding retinal bipolar response. Significance. We show that the OUReP is likely capable of eliciting responses in retinal bipolar cells necessary to generate vision under most ambient conditions.

DOI： 10.1088/1741-2552/abf892

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Retinal prostheses have been developed to restore vision in blind patients suffering from such diseases as retinitis pigmentosa. In our previous studies, we developed a retinal prosthesis called dye-coupled film by chemical coupling of photoelectric dyes, which absorb light and then generate electrical potential, with a polyethylene film surface. The dye-coupled film is nontoxic, and we recovered the vision of a monkey with macular degeneration. The amount of dye on the dye-coupled film, however, decreased to one-third after five months in the monkey's eye. The photoelectric dye consists of a cation with photoresponsivity and a bromide ion (Br-). Therefore, an anion-exchange reaction could be applied to the dye-coupled film to improve its durability. In this study, the anion-exchange reaction was conducted using bis(trifluoromethanesulfonyl)imide ion (TFSI-), which has lower nucleophilicity than Br-. First, the long-term durability was examined without using animal subjects and in a short period. Subsequently, an elemental analysis was performed to confirm the exchange between Br- and TFSI-, and chemical properties, such as photoresponsivity and durability, before and after the anion exchange, were evaluated. It was quantitatively confirmed that the long-term durability of dye-coupled films can be evaluated in an in vitro environment and in a short period of one-thirtieth by utilizing a saline solution at 60 degrees C, compared with an in vivo environment. In addition, the durability of the dye-coupled film with TFSI- was improved to 270%-320% compared with that of the dye-coupled film with Br-.

DOI： 10.1088/1748-605X/abe809

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGERNATURE  

Photoelectric dyes, which absorb light and generate electric potential, have been shown to stimulate retinal neurons. Therefore, in the present work, a photoelectric dye was used to develop a retinal prosthesis to restore vision loss due to diseases, such as retinitis pigmentosa. The retinal prosthesis, referred to as a dye-coupled film, was prepared by chemically coupling the dyes to a polyethylene film surface. However, the amount of coupled dye decreased during an implantation test in a monkey's eye. The dye consisted of a cation with photoresponsivity and Br-. Because thermal stability can be improved by anion exchange, we expected anion exchange to lead to stabilization of the chemical structure, resulting in improvement of the long-term durability of a retinal prosthesis. Therefore, the effects of exchanging Br- anions for PF6-, BF4-, and bis(trifluoromethanesulfonyl)imide (TFSI-) anions on the durability were investigated. The long-term durability of the dye-coupled films was found to be strongly related to the thermal stability of the photoelectric dye. The long-term durability of the dye-coupled film-PF6- and dye-coupled film-TFSI- improved by 637 and 215%, respectively, compared with that of the dye-coupled film-Br-.

DOI： 10.1038/s41428-021-00468-0

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Language：English   Publishing type：Research paper (scientific journal)  

NK-5962 is a key component of photoelectric dye-based retinal prosthesis (OUReP). In testing the safety and efficacy, NK-5962 was safe in all tests for the biological evaluation of medical devices (ISO 10993) and effective in preventing retinal cells from death even under dark conditions. The long-term implantation of the photoelectric dye-coupled polyethylene film in the subretinal space of hereditary retinal dystrophic (RCS) rats prevented neurons from apoptosis in the adjacent retinal tissue. The intravitreous injection of NK-5962 in the eyes of RCS rats, indeed, reduced the number of apoptotic cells in the retinal outer nuclear layer irrespective of light or dark conditions. In this study, we reviewed the in vitro and in vivo evidence of neuroprotective effect of NK-5962 and designed pharmacokinetic experiments. The in vitro IC50 of 1.7 μM, based on the protective effect on retinal cells in culture, could explain the in vivo EC50 of 3 μM that is calculated from concentrations of intravitreous injection to prevent retinal neurons from apoptosis. Pharmacokinetics of NK-5962 showed that intravenous administration, but not oral administration, led to the effective concentration in the eye of rats. NK-5962 would be a candidate drug for delaying the deterioration of retinal dystrophy, such as retinitis pigmentosa.

DOI： 10.3390/life11060591

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Single-walled carbon nanotubes (SWNTs) with lengths of several hundred nanometers were crystallized from dilute solutions, and slender lath-shaped SWNT crystals were obtained. The SWNTs were oriented along the long axis of the lath-shaped crystal, and the obtained crystals were two-dimensional crystals comprising hexagonally close-packed SWNTs. A relatively long SWNT acted as a crystalline nucleus. The length of the SWNT used for crystallization affected the morphology and growth rate of the crystals. Higher crystallization temperature shortened the time to precipitation, and the diffusion of SWNTs dominated the crystal growth of SWNT crystals. Because the short SWNTs were rigid with a wide length distribution, their tube ends were inevitably included in the crystals, resulting in crystal defects, such as lattice curvature and edge dislocations. These defects were directly observed by high-resolution electron microscopy. The mechanism for the crystallization of the SWNTs was proposed based on the observed morphologies, crystal defects, and crystallization process.

DOI： 10.1016/j.polymer.2021.123425

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

In this study, the preparation of poly (p-phenylene terephthalamide) (PPTA) single crystals was examined using crystallization from dilute solutions in concentrated sulfuric acid. Lozenge-shaped PPTA single crystals were successfully prepared using a self-seeding method with a low degree of supercooling, and they consisted of modification I crystals. The a-axis direction of the crystal corresponded to the long diagonal direction of the rhombus, the b-axis direction with the short diagonal direction, and the PPTA molecular chain direction (the c-axis direction) with the crystal's thickness direction. In addition, the PPTA single crystals had a (110) growth plane, where the thickness of each single crystal was approximately equal to the molecular chain length of the PPTA. Upon heat treatment of the PPTA single crystals, the symmetry changed from P1a1 to the more stable P11n. In addition, the heat treatment caused a difference in the density of each symmetric crystal, resulting in crack formation along the b-axis direction, which is the hydrogen-bonding direction. However, the heat treatment did not change the thickness of the PPTA single crystals. Conversely, the isothermal crystallization of the PPTA caused progression in the crystallization only under a high degree of supercooling, thus yielding plate-like PPTA crystals that consisted of modification II crystals. In these plate-like PPTA crystals, the length corresponded to the crystal a-axis direction, and the electron diffraction pattern was broad. Furthermore, the equilibrium dissolution temperature of the PPTA single crystals was discussed.

DOI： 10.1016/j.polymer.2020.122672

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Language：English   Publishing type：Research paper (scientific journal)  

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Authorship：Last author   Language：English   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Background: Vision plays a key role in some behavior tests for rats. Okayama University-type retinal prosthesis (OUReP) is a photoelectric dye-coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. This study aims to assess vision in retinal dystrophic (RCS) rats, in comparison with normal rats, by selected behavior tests. We also examined whether the tests could detect vision changes in RCS rats with dye-coupled film implantation.Methods: Data sets were 5 normal rats, 4 untreated RCS rats, 7 RCS rats with dye-coupled films implanted at the age of 7 weeks after excluding unsuccessful implantation at autopsy. Behavior tests chosen were landing foot splay and visual forelimb-placing response in the menu of functional observational battery, operant-conditioning lever-press response and light/dark box test.Results: Normal visual placing response was significantly less frequent in untreated RCS rats at the age of 9 and 11 weeks, compared with normal rats (P = 0.0027, chi-square test) while normal response was significantly more frequent at the age of 9 weeks in RCS rats with dye-coupled film implantation, compared with untreated RCS rats (P = 0.0221). In operant-conditioning lever-press test, the correct response rate was significantly lower in untreated RCS rats than in normal rats at the age of 9 weeks (P < 0.05, Tukey-Kramer test) while the rate was not significantly different between normal rats and RCS rats with dye-coupled film implantation. In light/dark box test, the time to enter dark box was significantly shorter in normal rats, compared with untreated RCS rats or RCS rats with dye-coupled film implantation (P < 0.05, Tukey-Kramer test).Conclusions: Behavior tests of functional observational battery, operant-conditioning lever-press response and light/dark box test discriminated vision between normal rats and RCS rats. The visual placing response and operant-conditioning lever-press test might have sensitivity to detect vision recovery in RCS rats with OUReP implantation.

DOI： 10.1016/j.heliyon.2019.e01936

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE SOC MEDICAL & BIOLOGICAL ENGINEERING  

Electrodes that output electric current as conduction current are widely used to stimulate nerves and cardiac cells in human body. We designed a photoelectric dye-coupled polyethylene film for use as a thin film device to stimulate nerve cells by electric potential changes. The aim of this study was to measure its photo-responsive properties and to record in vitro biological response. When measured using a Kelvin probe system, the photoelectric dye-coupled film showed rapid rise and fall of surface electric potential in response to light-on-and-off. Light-evoked surface electric potential of the dye-coupled film increased in response to increasing light intensity. In vitro biological response to the dye-coupled film was assessed in isolated rat retinal tissues using a multielectrode array recording system. As positive control, electroretinogram-like waves were recorded in response to light from normal rat retinal tissue placed with the inner retinal surface at the bottom of the multielectrode array dish. In contrast, no light-elicited wave was recorded from degenerative retinal tissue isolated from retinal dystrophic Royal College of Surgeons (RCS) rats. When the dye-coupled film was simply overlaid on the degenerative retinal tissue with the inner retinal surface placed at the bottom of the multielectrode array dish, electroretinogram-like waves were elicited in response to light projected from the bottom. Plain polyethylene film without photoelectric dye coupling was used as negative control, and did not yield light-elicited response when placed on the degenerative retinal tissue. For detailed recordings of action potential spikes high-passed at 100 Hz, a nylon mesh anchor was placed on top of the preparation to ensure close contact between the multielectrode array and the retinal tissue with or without the dye-coupled film. In this experimental setting, the degenerative retinal tissue alone showed spontaneous action potential spikes as numerous small trivial amplitudes in the background noise, while the degenerative retinal tissue overlain with the dye-coupled film showed action potential spikes with increased amplitude in response to light against the background of spontaneous spikes. This study confirmed that the photoelectric dye-coupled polyethylene film is able to stimulate degenerative retinal tissue that has lost photoreceptor cells, and may function as a novel type of retinal prosthesis. Electric potential changes, probably as displacement current or capacitive current, may be an alternative approach to stimulate nerves in human body.

DOI： 10.14326/abe.8.137

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：SOC FIBER SCIENCE TECHNOLOGY  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Retinal prosthesis or artificial retina is a promising modality of treatment for outer retinal degeneration, caused by primary and secondary loss of photoreceptor cells, in hereditary retinal dystrophy and age-related macular degeneration, respectively. Okayama University-type retinal prosthesis (OUReP) is a photoelectric dye-coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. The dyecoupled films were implanted by vitreous surgery in the subretinal space of monkey eyes with macular degeneration which had been induced by cobalt chloride injection from the scleral side. A pilot 1-month observation study involved 6 monkeys and a pivotal 6-month observation study involved 8 monkeys. Of 8 monkeys in 6-month group, 3 monkeys underwent dye-coupled film removal at 5 months and were observed further for 1 month. The amplitude of visual evoked potential which had been reduced by macular degeneration did recover at 1 month after film implantation and maintained the level at 6 months. Optical coherence tomography showed no retinal detachment, and full-field electroretinograms maintained a-wave and b-wave amplitudes, indicative of no retinal toxicity. Pathological examinations after 6-month implantation showed structural integrity of the inner retinal layer in close apposition to dye-coupled films. The implanted films which were removed by vitrectomy 5 months later showed light-evoked surface electric potentials by scanning Kelvin probe measurement. The photoelectric dye-coupled film (OUReP), which serves as a light-receiver and a displacement current generator in the subretinal space of the eye, has a potential for recovering vision in diseases with photoreceptor cell loss, such as retinitis pigmentosa and age-related macular degeneration.

DOI： 10.1111/aor.13120

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC VET SCI  

Okayama University-type retinal prosthesis (OURePTM) is a photoelectric dye-coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. This study aims to test surgical feasibility for subretinal film implantation and to examine functional durability of films in subretinal space. Dye-coupled films were implanted subretinally by vitrectomy in the right eye of normal white rabbits: 8 rabbits for 1 month and 8 rabbits for 6 months. The implanted films were removed by vitrectomy in 4 of these 8 rabbits in 1-month or 6-month implantation group. The films were also implanted in 4 rhodopsin-transgenic retinal dystrophic rabbits. Visual evoked potential was measured before film implantation as well as 1 or 6 months after film implantation, or 1 month after film removal. The films were successfully implanted in subretinal space of retinal detachment induced by subretinal fluid injection with a 38G polyimide tip. The retina was reattached by fluid-air exchange in vitreous cavity, retinal laser coagulation, and silicone oil injection. The ratios of P-2 amplitudes of visual evoked potential in the implanted right eye over control left eye did not show significant changes between pre-implantation and post-implantation or post-removal (paired t-test). In Kelvin probe measurements, 4 pieces each of removed films which were implanted for 1 or 6 months showed proportional increase of surface electric potential in response to increasing light intensity. The film implantation was safe and implanted films were capable of responding to light.

DOI： 10.1292/jvms.17-0422

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Leptothrix species produce microtubular organic-inorganic materials that encase the bacterial cells. The skeleton of an immature sheath, consisting of organic exopolymer fibrils of bacterial origin, is formed first, then the sheath becomes encrusted with inorganic material. Functional carboxyl groups of polysaccharides in these fibrils are considered to attract and bind metal cations, including Fe(III) and Fe(III)-mineral phases onto the fibrils, but the detailed mechanism remains elusive. Here we show that NH2 of the amino-sugar-enriched exopolymer fibrils is involved in interactions with abiotically generated Fe(III) minerals. NH2-specific staining of L. cholodnii OUMS1 detected a terminal NH2 on its sheath skeleton. Masking NH2 with specific reagents abrogated deposition of Fe(III) minerals onto fibrils. Fe(III) minerals were adsorbed on chitosan and NH2-coated polystyrene beads but not on cellulose and beads coated with an acetamide group. X-ray photoelectron spectroscopy at the N1s edge revealed that the terminal NH2 of OUMS1 sheaths, chitosan and NH2-coated beads binds to Fe(III)-mineral phases, indicating interaction between the Fe(III) minerals and terminal NH2. Thus, the terminal NH2 in the exopolymer fibrils seems critical for Fe encrustation of Leptothrix sheaths. These insights should inform artificial synthesis of highly reactive NH2-rich polymers for use as absorbents, catalysts and so on.

DOI： 10.1038/s41598-017-06644-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

Photoelectric dye-coupled polyethylene film, designated Okayama University type-retinal prosthesis or OUReP (TM), generates light-evoked surface electric potentials and stimulates neurons. The dye-coupled films or plain films were implanted subretinally in both eyes of 10 Royal College of Surgeons rats with hereditary retinal dystrophy at the age of 6 weeks. Visual evoked potentials in response to monocular flashing light stimuli were recorded from cranially-fixed electrodes, 4 weeks and 8 weeks after the implantation. After the recording, subretinal film implantation was confirmed histologically in 7 eyes with dye-coupled films and 7 eyes with plain films. The recordings from these 7 eyes in each group were used for statistical analysis. The amplitudes of visual evoked potentials in the consecutive time points from 125 to 250 ms after flash were significantly larger in the 7 eyes with dye-coupled film implantation, compared to the 7 eyes with plain film implantation at 8 weeks after the implantation (P < 0.05, repeated-measure ANOVA). The photoelectric dye-coupled polyethylene film, as retinal prosthesis, gave rise to visual evoked potential in response to flashing light.

DOI： 10.1007/s10047-016-0943-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MARY ANN LIEBERT, INC  

Purpose: Our previous study demonstrated that photoelectric dye-coupled polyethylene film (Okayama University-type retinal prosthesis), which was implanted in subretinal space of the eyes of Royal College of Surgeons (RCS) rats, prevented retinal neurons from apoptotic death. In this study, we aimed to examine whether photoelectric dye itself would protect retinal neurons from apoptosis in RCS rats.Methods: RCS rats received intravitreous injection of different concentrations of the dye in the left eye and housed under a 12-h light-dark cycle. Saline injection in the right eye served as control. In addition, RCS rats with dye injection were kept in 24-h daily dark condition. Sections were processed for terminal deoxynucleotidyl transferase-mediated fluorescein-conjugated-dUTP nick-end-labeling (TUNEL) assay and immunohistochemical staining of glial fibrillary acidic protein (GFAP) and protein kinase C alpha (PKC alpha).Results: The number of TUNEL-positive cells significantly decreased in the retina of dye-injected eyes compared with those in saline-injected eyes (P = 0.0001, 2-factor analysis of variance [ANOVA]), under 12-h light-dark cycle. Significant decrease of TUNEL-positive cells was noted in the retina of rats with dye injection compared with those with saline injection, kept under 24-h dark condition (P = 0.0001, 2-factor ANOVA). Immunoreactive area for GFAP decreased significantly in the retina of dye-injected eyes compared with that in controls (P = 0.0001, 2-factor ANOVA), whereas immunoreactive area for PKCa increased significantly in the retina of dye-injected eyes compared with that in controls (P = 0.01, 2-factor ANOVA).Conclusions: Photoelectric dye inhibits apoptotic death of photoreceptor cells in RCS rats and downregulates GFAP expression in retinal Muller cells. Photoelectric dye may be a candidate agent for neuroprotection in retinitis pigmentosa and other retinal diseases.

DOI： 10.1089/jop.2016.0093

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Size control of the poly (1,4-phenylene-5-hydroxyisophthalamide) hollow spheres was examined by tuning the polymerization condition, focusing on concentration, temperature and solvent. Higher concentration lowered the diameter owing to the higher degree of super-saturation for nucleation. Temperature drop during the polymerization just before the nucleation was so effective to make the diameter smaller. Moreover, the diameter was susceptive to the solubility of oligomers in the solvent, and higher content of liquid paraffin in the aromatic solvent lowered the solubility, resulting in the decrease in the diameter. Based on these results, the combination of the temperature drop and the solvent effect was the most desirable to prepare the smallest hollow spheres, and the diameter of hollow spheres could be controlled from 4.4 to 0.7 mu m. (C) 2017 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2017.01.060

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC VET SCI  

Okayama University-type retinal prosthesis (OUReP (TM)) is a photoelectric dye-coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. This study aims to test surgical feasibility of subretinal implantation and functional durability of dye-coupled films in the subretinal space. The dye-coupled films were implanted subretinally by 25-gauge vitrectomy in the right eye of 11 normal beagle dogs: 2 dogs served for film removal after 5-month film implantation, 3 dogs for film removal after 3-month film implantation, 3 dogs for 3-month film implantation and pathological examination, and 3 dogs for sham surgery. The surface electric potential of the removed dye-coupled films in response to light was measured by the Kelvin Probe system. At surgery, rolled-up dye-coupled films in 5 x 5 mm square size could be inserted into subretinal space of retinal detachment induced by fluid injection with a 38-gauge polyimide tip. Retinal attachment was maintained by silicone oil injection in vitreous cavity. At autopsy, the retina in all dogs maintained the ganglion cell layer, inner and outer nuclear layers while it lost the outer segments in some part. All 5 sheets of removed dye-coupled films maintained the dye color. One sheet of the 5-month implanted film showed proportional increase of surface potential in response to increasing light intensity. Subretinal implantation of OUReP (TM) by vitrectomy was technically feasible in canine eyes, and OUReP (TM) maintained the function of generating light-evoked surface potential after 5 months in subretinal implantation.

DOI： 10.1292/jvms.17-0450

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Poly(vinyl alcohol) (PVA) was crystallized from a dilute solution in the presence of cellulose nanofibers (CeNFs). The CeNFs acted as nucleating agents for PVA crystallization, and PVA crystals were grown on the CeNFs' surface. As a result, CeNFs coated with PVA crystals (CeNF/PVA nanocomposite fiber (NCF(CeNF/PVA))) were successfully obtained. The NCF(CeNF/PVA) showed good dispersibility in water even after drying. Composite films were prepared using the aforementioned NCF(CeNF/PVA) and their mechanical properties were measured. Despite the low content of NCF(CeNF/PVA=1/5) (0.1 wt%, corresponding to 1.7 x 10(-2) wt% CeNF), the mechanical properties of the composite films improved in comparison to those of the control samples. This reinforcement effect of the NCF(CeNF/PVA=1/5) was greater than that of pure CeNFs. Surface modification of the NCF was also discussed, and the surface hydrophilicity of the NCF could be controlled depending on the choice of coating crystal.

DOI： 10.1039/c7ra01062a

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC FIBER SCIENCE TECHNOLOGY  

Poly(p-phenylene benzobisthiazole) (PBZT) Was crystallized from dilute solution in the presence of single-wall carbon nanotube (SWNT) or multi-wall carbon nanotube (MWNT). In this crystallisation condition, SWNT existed as pristine bundles. SWNT bundles and MWNT acted as nucleating agents of PBZT crystallisation.The nucleating effect of the SWNT bundle was larger than that of MWNT. Transmission electron microscope observation revealed that the morphology of the PBZT crystal on the carbon nanotube (CNT) could be controlled by crystallization condition such as molecular length of PBZT, H2SO4 concentration, variety of CNT. Thermal stability of PBZT crystallized on SWNT bundles was discussed by the observation of crystal dissolution temperature.

DOI： 10.2115/fiberst.2017-0001

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Language：English   Publisher：ASSOC RESEARCH VISION OPHTHALMOLOGY INC  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Preparation of poly[4-(5-oxy-1,3-dioxoisoindoline-2-yl)benzoyl] (PODB) crystals, which was an intractable aromatic poly(ester-imide), was examined by means of reaction-induced crystallization of oligomers during the polymerization. Highly crystalline PODB helical ribbons were obtained by the polymerization of N-(4-carboxyphenyl)-4-acetoxyphthalimide in aromatic solvent at 280-330 degrees C at a concentration of 0.5-1.0%. The PODB molecules aligned along the long axis of the helical ribbon. The pitch of the helix increased with the polymerization temperature and it could be controlled from 320 nm to 1.3 mu m. Further, the fibrillar PODB crystals comprised of the helical and the non-helical blocks were prepared by the on-off switching of the helical morphology with the changing the temperature and the concentration of the polymerization. These results provided the methodology for the morphology control of polymer crystals. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2016.06.055

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Helical ribbons of poly[4-(5-oxy-1,3-dioxoisoindoline-2-yl) benzoyl] (PODB) were previously prepared by the homo-polymerization of N-(4-carboxyphenyl)-4-acetoxyphthalimide (CAP) in aromatic solvents. The copolymerization of CAP and p-acetoxybenzoic acid (ABA) was examined to change the helical morphology. The helical morphology was extinguished by the copolymerization of a small amount of ABA at 280 degrees C at a concentration of 1.0% in aromatic solvent. Based on these results, ABA was added stepwise during the homo-polymerization of CAP. When a small amount of ABA was added, copolymer crystals comprised of helical and non-helical blocks were formed. The non-helical blocks grew on the PODB helical ribbons by the precipitation of co-oligomers. This result provides a novel method to control helical morphology by copolymerization.

DOI： 10.1039/c6ra22494f

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Hollow spheres of poly(1,4-phenylene-5-hydroxyisophthalamide) had been obtained by the reaction-induced phase separation during polymerization of 5-hydroxyisophthalic acid and 1,4-phenylene diamine in an aromatic solvent. In this study, formation mechanism of the hollow spheres was considered from the view points of eliminated small molecules, polymer structure, and cross-linking reaction. With respect to the eliminated small molecules, water was the most desirable to form gas-bubbles in droplets compared with methanol and acetic acid, due to the insolubility into the polymerization system. Rigid polymer structure was also needed to prepare hollow spheres owing to the rapid solidification of droplets. Further, phenolic hydroxyl group in 5-hydroxy-1,3-phenylene moiety caused the ester-amide exchange reaction to form cross-linked skin layer in the droplets. The efficient formation of the skin layer was important to encapsulate gas-bubbles in the droplets, resulting in the formation of hollow structure. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1966-1974

DOI： 10.1002/pola.27683

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

Photoelectric dye-coupled polyethylene film, designated Okayama University-type retinal prosthesis or OUReP (TM), generates light-evoked surface electric potentials and stimulates neurons. In this study, the vision was assessed by behavior tests in aged hereditary retinal dystrophic RCS rats with OUReP (TM), retinal apoptosis and electroretinographic responses were measured in dystrophic eyes with OUReP (TM). The dye-coupled films, or plain films as a control, were implanted in subretinal space of RCS rats. On behavior tests, RCS rats with dye-coupled films, implanted at the old age of 14 weeks, showed the larger number of head-turning, consistent with clockwise and anticlockwise rotation of a surrounding black-and-white-striped drum, compared with rats with plain films, under the dim (50 lux) and bright (150 lux) conditions in the observation period until the age of 22 weeks (n = 5, P < 0.05, repeated-measure ANOVA). The number of apoptotic cells in retinal sections at the site of dye-coupled film implantation was significantly smaller, compared with the other retinal sites, neighboring the film, or opposite to the film, 5 months after film implantation at the age of 6 weeks (P = 0.0021, Friedman test). The dystrophic eyes of RCS rats with dye-coupled films showed positive responses to maximal light stimulus at a significantly higher rate, compared with the eyes with no treatment (P < 0.05, Chi-square test). Electroretinograms in normal eyes of Wistar rats with dye-coupled or plain films showed significantly decreased amplitudes (n = 14, P < 0.05, repeated-measure ANOVA). In conclusions, vision was maintained in RCS rats with dye-coupled films implanted at the old age. The dystrophic eyes with dye-coupled films showed electroretinographic responses. Five-month film implantation caused no additional retinal changes.

DOI： 10.1007/s10047-015-0825-1

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：TECHNICAL ASSOC PHOTOPOLYMERS,JAPAN  

Photoelectric dyes that absorb light and convert photon energy to electric potential have previously been shown to stimulate retinal neurons in cultures. As such, we have designed a new type of retinal prosthesis using polyethylene films coupled with photoelectric dye molecules. In this study, the electric potentials on the film were observed using a scanning Kelvin probe microscope under light and dark conditions. As a result, electric potentials were observed on the film, which were dependent on light intensity and wavelength. Furthermore, the electric potentials showed a rapid on off response to light.

DOI： 10.2494/photopolymer.28.261

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：TECHNICAL ASSOC PHOTOPOLYMERS,JAPAN  

A rigid polymer network of poly(p-phenylene benzobisoxazole) (PBO) has excellent mechanical properties and thermal stability. Many nano voids exist within the network. However, a PBO network cannot be formed into films or fibers. Generally, PBO networks are prepared by one-step polycondensation in polyphosphoric acid. In this study, we have prepared a PBO network by a two-step method involving polymerization of a PBO network precursor (pre-PBO network) in N-methyl-2-pyrrolidone followed by thermal cyclization. Heat-resistant porous PBO network films have been successfully obtained by this two-step method. The properties of the PBO network films have been evaluated.

DOI： 10.2494/photopolymer.28.163

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER INTERNATIONAL PUBLISHING AG  

Purpose: Glass transition temperature is a main indicator for amorphous polymers and biological macromolecules as materials, and would be a key for understanding the role of trehalose in protecting proteins and cells against desiccation. In this study, we measured the glass transition temperature by differential scanning calorimetry of dried lens tissues as a model of a whole biological tissue to know the effect of pretreatment by trehalose and other sugars.Methods: Isolated porcine lenses were incubated with saline, 100 or 1000 mM concentration of trehalose, maltose, or cyclic tetrasaccharide dissolved in saline at room temperature for 150 minutes. The solutions were removed and all samples were dried at room temperature in a desiccator until no weight change. The dried tissues were ground into powder and placed in a measuring pan for differential scanning calorimetry.Results: The glass transition temperature of the dried lens tissues, as a mean and standard deviation, was 63.0 +/- 6.4 degrees C (n = 3) with saline pretreatment; 53.0 +/- 0.8 degrees C and 56.3 +/- 2.7 degrees C (n = 3), respectively, with 100 and 1000 mM trehalose pretreatment; 56.0 +/- 1.6 degrees C and 55.8 +/- 1.1 degrees C (n = 3), respectively, with 100 and 1000 mM maltose pretreatment; 60.0 +/- 8.8 degrees C and 59.2 +/- 6.3 degrees C (n = 3), respectively, with 100 and 1000 mM cyclic tetrasaccharide pretreatment. The glass transition temperature appeared lower, although not significantly, with trehalose and maltose pretreatments than with saline and cyclic tetrasaccharide pretreatments (P > 0.05, Kruskal-Wallis test). The glass transition temperature of the dried lens tissues with trehalose pretreatment appeared more noticeable on the thermogram, compared with other pretreatments.Conclusions: The glass transition temperature was measured for the first time in the dried lens tissues as an example of a whole biological tissue and might provide a basis for tissue preservation in the dried condition.

DOI： 10.1186/2193-1801-3-317

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Language：English   Publisher：ASSOC RESEARCH VISION OPHTHALMOLOGY INC  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：TECHNICAL ASSOC PHOTOPOLYMERS,JAPAN  

Poly(p-phenylene benzobisoxazole) (PBO) has excellent thermal stability and mechanical properties because of its rod-like rigid structure. Preparing nanofibers of PBO using ordinary methods is difficult (e.g., electrospinning) because PBO is not soluble in organic solvents. Herein, we report the preparation of PBO nanofibers with an average diameter of approximately 50 nm via crystallization from a dilute solution in sulfuric acid. In addition, a PBO nanofiber mat was prepared that exhibited extremely high thermal stability and high thermal diffusivity, etc.

DOI： 10.2494/photopolymer.27.177

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

We have developed a photoelectric dye-coupled polyethylene film as a prototype of retinal prosthesis, which we named Okayama University-type retinal prosthesis. The purposes of this study are to conduct behavior tests to assess vision in Royal College of Surgeons (RCS) rats that underwent subretinal implantation of the dye-coupled film and to reveal retinal response to the dye-coupled film by immunohistochemistry. Polyethylene films were made of polyethylene powder at refined purity, and photoelectric dyes were coupled to the film surface at higher density compared with the prototype. Either dye-coupled film or dye-uncoupled plain film used as a control was implanted subretinally from a scleral incision in both eyes of an RCS rat at 6 weeks of the age. Behavior tests 2, 4, 6, and 8 weeks after implantation were conducted by observing head turning or body turning in the direction consistent with clockwise or counterclockwise rotation of a black-and-white-striped drum around a transparent cage housed with the rat. After the behavior tests at 8 weeks, rats' eyes were enucleated to confirm subretinal implantation of the films and processed for immunohistochemistry. In the behavior tests, the number of head turnings consistent with the direction of the drum rotation was significantly larger in RCS rats with dye-coupled- compared with plain-film implantation [P < 0.05, repeated-measure analysis of variance (ANOVA), n = 7]. The number of apoptotic neurons was significantly smaller in eyes with dye-coupled- compared with plain-film implantation (P < 0.05, Mann-Whitney U test, n = 6). In conclusion, subretinal implantation of photoelectric dye-coupled films restored vision in RCS rats and prevented the remaining retinal neurons from apoptosis.

DOI： 10.1007/s10047-013-0697-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Poly(2,6-1H-benzo[f]isoindole-1,3(2H)-dione) (PBID), which was a self-condensable naphthalene-containing polyimide, was synthesized as precipitated crystals from 6-amino-3-(ethoxycarbonyl)-2-naphthoic acid and 7-amino-3-(ethoxycarbonyl)-2-naphthoic acid by using reaction-induced crystallization during solution polymerization. The obtained PBID crystals possessed high crystallinity, excellent thermal stability and chemical resistance. They neither exhibited Tg nor Tm under the decomposition temperature. The morphology of the PBID crystals depended on not only the polymerization conditions but also the isomeric structure of the monomer, and the wide variety of the morphology appeared such as rods, plates and lathes. The plate-like crystals had fine protuberances on the surface. Copolymerization of PBID and poly(4-phthalimide) were also examined. (c) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.eurpolymj.2013.05.021

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Poly(p-oxybenzoyl) (POB) precipitates prepared by reaction-induced phase separation during copolymerization exhibit wide variety of morphologies such as fibril, needle, slab, spindle, and sphere. The morphology is significantly influenced by the copolymerization conditions of structure of trifunctional comonomers, copolymerization ratio, solvent, concentration, and temperature of the polymerization. Among them, POB nanofiber networks like a texture of nonwoven fabrics are obtained only by the polymerization of 4-acetoxybenzoic acid with 3,5-diacetoxybenzoic acid (DABA) in aromatic solvent at a concentration of 1.0-2.0% at the content of DABA in feed of 10-20 mol % at 320 degrees C. The network is comprised of fibrillar crystals connected each other at spherical nodal points. The diameters of the fibers are 90-129 nm. This network is highly crystalline and the molecules are aligned along the long direction of the fibers. Various parameters characterized the networks can be controlled by the polymerization concentration. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 1282-1290, 2013

DOI： 10.1002/app.38554

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Hollow spheres of aromatic polyamide are obtained by the reaction-induced phase separation during polymerization of 5-hydroxyisophthalic acid and 1,4-phenylene diamine in an aromatic solvent at a concentration of 1-2% at 320 degrees C without stirring. The hollow sphere has a dimple hole and the diameters of the hollow spheres are 3-4 mu m. The droplets are initially generated via liquid-liquid phase separation and then rigid crosslinked network structure formed the rigid skin layer on the surface of the droplets. The solidification of the droplets occurred owing to the further polymerization in them with maintaining the morphology to form the hollow spheres. The hollow spheres exhibit outstanding thermal stability. (C) 2012 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 780-785

DOI： 10.1002/pola.26467

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ROYAL SOC CHEMISTRY  

Direct incorporation of a Pt(II) complex into the shell of SWCNT/fullerodendron coaxial nanohybrids produces a new coaxial nanowire, SWCNT/fullerodendron/Pt(II), that shows efficient photocatalytic activity for hydrogen evolution from water (Phi = 0.16 upon irradiation at 450 +/- 5 nm) without any aid of electron relay such as methyl viologen.

DOI： 10.1039/c3nj00790a

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：TECHNICAL ASSOC PHOTOPOLYMERS,JAPAN  

DOI： 10.2494/photopolymer.26.341

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

Morphology control of poly(ether ketone) (PEK) was examined by using the crystallization during the nucleophilic aromatic substitution reaction of potassium salt of 4-fluoro-4'-hydroxybenzophenone. Polymerizations were carried out at 290 degrees C. The PEK was obtained as precipitates and its morphology was highly influenced by the polymerization condition such as the solvent, the concentration and the polymerization time. High crystalline spindle-like crystals were obtained by the polymerization in diphenyl sulfone (DPS) at a concentration of 5.0% for 2 h with the yield of 86%. The average length and width were 1.4 mu m and 300 nm respectively, and the maximum thickness was 130 nm. The surface was not smooth and it was hilly. The spindle-like crystal was likely consisted of multilayered lamellae comprised of the microcrystallites. The molecules were oriented perpendicular to the lamella. The polymerization in DPS at a higher concentration of 10.0% afforded the networks of nanofibres, of which the diameter was 100-250 nm. The obtained PEK precipitates possessed excellent thermal properties. (C) 2012 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.eurpolymj.2012.07.004

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Morphosynthesis of poly[4-(1,4-phenylene)oxyphthalimide] (POPI) and poly[4-(1,4-phenylene)oxyphthalimide-co-4-phthalimide] (POPI-PPI) was examined by using the crystallization during the polymerization. The POPI fibrillar crystals were obtained as precipitates with the formation of spherical aggregates of plate-like crystals. Some of the POPI fibrillar crystals were longer than 15 mu m. They possessed high crystallinity and the molecules aligned perpendicular to the long direction of the fibers. On the other hand, one-dimensional structures of POPI-PPI such as ribbon, cone, rod, and fiber were obtained as precipitates by the copolymerization. The copolymer molecules might align along the long direction of the cone-like crystals. The morphology of these poly(ether-imide)s could be controlled by not only the polymerization condition but also with the aid of copolymerization. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012

DOI： 10.1002/polb.23122

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Morphology of four kinds of aromatic polyimidazoles was examined by using reaction-induced crystallization during solution polymerization at a concentration of 1% at 350 degrees C in liquid paraffin (LPF), dibenzyltoluene (DBT), and the mixture of these solvents. Aggregates of ribbon-like crystals of poly[2,6-(2,6-naphthalene)-benzobisimidazole] were obtained in LPF, and those of plate-like crystals were obtained in DBT/LPF-50 and in DBT. In contrast to this, the network structures of poly[2,2'-(2,6-naphthalene)-5,5'-bibenzimidazole)] (PNT-BBI) nanofibers with the diameter of 25 to 90 nm was mainly obtained in DBT. The network structures of the PNT-BBI nanofibers could be recognized as nonwoven fabrics of the high-performance polymers. Imidazole trimers were precipitated to form the ribbon-like crystals and then they were continuously supplied from solution to grow the crystals. Molecular weight increased by the polymerization on the surface of the crystals when they crystallized and in the crystals. The initially formed aggregates of ribbon-like crystals changed to the nanofibers with time. In the case of poly[2,6-(4,4'-biphenylene)-benzobisimidazole] and poly[2,2'-(4,4'-biphenylene)-5,5'-bibenzimidazole)], they exhibited various morphologies such as spheres, lath-like crystals, and the spherical aggregates of lath-like crystals depending on the solvent, but fibers like PNT-BBI were not formed. The crystals obtained in this study possessed very high crystallinity and the outstanding thermal stability measured by TGA. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 2851-2860, 2011

DOI： 10.1002/app.33914

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Language：Japanese   Publisher：SOC FIBER SCIENCE TECHNOLOGY  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Morphology control of poly(p-phenylene pyromelliteimide) (PPPI) crystals was examined using reaction-induced crystallization of oligomers during solution polymerization of self-polymerizable N-(4'-aminophenyl)-3-carboxyl-4-alkoxycarbonylPhthalimide. Micro-flowers of the PPP1 needle-like crystals were formed in which the needle-like crystals grew radially from the center part as petals. The molecules aligned regularly along the long axis of the needle-like crystal. The structure of alkoxy group in the monomer and the monomer concentration influenced the size of the needle-like crystals, and their average length and width were changeable from 640 nm to 1.69 mu m and from 110 nm to 210 nm, respectively. The average thickness was 20 nm. The obtained micro-flowers possessed high crystallinity and exhibited excellent thermal stability. (C) 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2010.12.022

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Polymerizations of 4-(4-acetoxybenzylideneamino)-benzoic acid were performed in dibenzyltoluene (DBT) and a mixture of DBT and liquid paraffin at 350 degrees C for 6 h. Fibrillar crystals of poly[4-(4-oxybenzylideneamino)benzoyl] (POAB) having the width of 50-450 nm and the length of over 15 pm were obtained by the crystallization during the polymerization. The fibrillar crystals possessed high crystallinity and the molecular chains aligned perpendicular to the long axis of the fibrillar crystals. Plate-like crystals were initially formed by the crystallization of oligomers, and then they changed to the fibrillar crystals via the formation of bundle-like crystals after 1 h. Molecular weight increased by the further polymerization in the crystals. Based on these results, one-pot preparation of the fibrillar POAB crystals was examined by the polymerization of 4-acetoxybenzaldehyde and 4-aminobenzoic acid. The polymerization at 180 degrees C for 2 h and then at 350 degrees C for 6 h afforded the fibrillar crystals with a small amount of the ribbon-like crystals. Although the side-reaction to generate the p-benzamide sequences was not completely depressed, the sequence of heating in which 180 degrees C for the formation of the azomethine linkage and then 350 degrees C for the formation of the ester linkage was preferable to prepare the fibrillar POAB crystals. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 127-137, 2011

DOI： 10.1002/pola.24427

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Trehalose, a non-reducing disaccharide, is known as an exceptional protector against desiccation and heat stress. Differential scanning calorimetry is a simple tool to determine thermodynamic parameters concerning the structural state of proteins. In this study, we measured denaturation temperature (or melting temperature) of dried lenses to know the effect of trehalose pretreatment. Isolated porcine lenses were incubated in wells without any solution or with saline, 100 mM trehalose, or 100 mM cyclic tetrasaccharide in saline at room temperature for 150 min. The solutions were removed, and all lens samples were dried at room temperature and in room humidity until the weight showed no change. The nucleus of each sample was taken out and placed on a measuring platform for differential scanning calorimetry. The denaturation temperature of the dried lenses significantly rose by about 10 degrees C with 100 mM trehalose pretreatment, compared to no pretreatment, pretreatment with saline or 100 mM cyclic tetrasaccharide (P < 0.05, analysis of variance, P < 0.05, Student-Newman-Keuls tests, n = 7). The denaturation temperature showed no difference among the dried lenses with no pretreatment or pretreatment by saline or cyclic tetrasaccharide. In conclusion, pretreatment with trehalose raises denaturation temperature of the dried porcine lens. Trehalose might stabilize the dried tissue structure to get a higher denaturation temperature.

DOI： 10.1007/s10973-010-0906-6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

Preparation of discrete PPPI microspheres was examined using the crystallization of oligomers during isothermal polymerization of PMDA and p-phenylene diisocyanate, and that of pyromellitic dithioanhydride and PPDA in poor solvents. In contrast to PPPI microspheres with smooth surfaces that were previously prepared by phase-separation during the polymerization of PPDA and PMDA, the microspheres obtained here consisted of flake-like lamellae with rugged surfaces. The diameters of the microspheres ranged from 0.5 to 6.7 mu m. They exhibited excellent thermal stability depending on the monomers. These results provide a new preparative procedure of the PPPI microsphere with a rugged surface.

DOI： 10.1002/macp.201000510

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

The preparation of poly[2,6-(1,4-phenylene)-benzobisimidazole] (PPBI) nanofibers was examined using the crystallization of oligomers during isothermal polymerization of self-polymerizable 2-(1,4-carbophenoxyphenyl)-5,6-diaminobenzimidazole. The polymerization was carried out at 350 degrees C at a concentration of 1w-t.-% for 6 h in three kinds of solvent. The solvent influenced the morphology of PPBI precipitates significantly, and PPBI nanofiber networks were successfully formed in DBT, of which the width ranged from 30 to 110 nm. Molecules were aligned along the long axis of nanofibers. A fibrillar morphology with molecular orientation is ideal for high performance materials such as reinforcements, non-woven fabrics and so on. The nanofiber networks exhibit the highest thermal stability.

DOI： 10.1002/macp.201000306

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Morphological control of poly(2,5-benzimidazole) (PBI) was examined by reaction-induced phase separation of oligomers during polymerization to prepare nanofibers. Three monomers, 3,4-diaminobenzoic acid (DABA), 3,4-diacetoamidebenzoic acid (DAcBA) and phenyl 3,4-diaminobenzoate (PDAB), were used to synthesize PBI. Polymerizations were carried out at 350 degrees C in a mixture of dibenzyltoluene isomers. Polymerization of DABA yielded spheres with plate-like crystals on their surface. Polymerization of DAcBA yielded almost no precipitates because of the high solubility of DAcBA oligomers. By contrast, polymerization of PDAB yielded aggregates of PBI nanofibers (of which the average diameter was similar to 60 nm), which resembled nonwoven fabrics. These fibers were formed by precipitation of (2,5-benzimidazole) oligomers and their subsequent polymerization into a developing crystal structure. The structure of the monomer significantly influenced the morphology of the PBI product, and PDAB was preferable for the preparation of PBI nanofibers. The temperature of 10% N-2 weight loss in these nanofibers was in the range of 634-644 degrees C and they were thermally stable. Polymer Journal (2010) 42, 375-382; doi:10.1038/pj.2010.20; published online 17 March 2010

DOI： 10.1038/pj.2010.20

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Language：English   Publisher：SPRINGER TOKYO  

Patients with retinitis pigmentosa lose photoreceptor cells as a result of genetic abnormalities and hence become blind. Neurons such as bipolar cells and ganglion cells remain alive even in the retina of these patients, and ganglion cells send axons to the brain as the optic nerve. The basic concept of retinal prostheses is to replace dead photoreceptor cells with artificial devices to stimulate the remaining neurons with electric currents or potentials. Photodiode arrays and digital camera-type electrode arrays are the two main approaches for retinal prostheses to stimulate retinal neurons, but these arrays have the problems of poor biocompatibility, low sensitivity, and low output of electric currents, and hence have a requirement for external electric sources (batteries). To overcome these problems, we are developing photoelectric dye-based retinal prostheses that absorb light and convert photon energy to generate electric potentials. The prototype, using a photoelectric dye-coupled polyethylene film, could induce intracellular calcium elevation in photoreceptor-lacking embryonic retinal tissues and cultured retinal neurons. The subretinal implantation of the prototype in the eyes of Royal College of Surgeons (RCS) rats led to vision recovery as proved by a behavior test. The photoelectric dye that was chosen for the prototype did not exhibit any cytotoxicity. The surface potentials of the photoelectric dye-coupled film showed a rapid on-and-off response to illumination with a threshold for light intensity as measured by a Kelvin probe system. Photoelectric dye-based retinal prostheses are thin and soft, and therefore, a sheet of the film of large size, corresponding to a large visual field, could be inserted into the vitreous and then to the subretinal space through a small opening by rolling up the film. Clinical studies of photoelectric dye-based retinal prostheses in patients with retinitis pigmentosa who lose sight will be planned after the manufacturing control and the quality control had been established for the medical device.

DOI： 10.1007/s10047-009-0471-6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Direct synthesis of rigid-rod aromatic polyamides was studied without condensation reagents by using reaction-induced crystallization of oligomers during solution polymerization. Polymerizations of p-aminobenzoic acid were carried out in an aromatic solvent at a polymerization concentration of 20% at 350 degrees C. High molecular weight poly(p-benzamide) (PBA) was obtained in the form of plate-like crystals, and the highest molecular weight was 11.6 x 10(3). In this polymerization, the oligomers were formed in the solution by the condensation reaction with the elimination of water. When the molecular weight of oligomers exceeded the critical value, the oligomers were precipitated by crystallization via supersaturated state to form the plate-like crystals. The molecular weight increased by the polymerization between the oligomers on and in the crystals. Poly(p-phenylene isophthalamide) (PPIA) was also obtained in the form of plate-like crystals by the polymerization of p-phenylene diamine (PPDA) and isophthalic acid (IPA) under the same condition as that of PBA. These results exhibited the thermally direct synthesis of infusible aromatic polyamides. Sequential addition of monomers into this heterogeneous polymerization was examined to increase the molecular weight. In the step-growth polymerization, the addition of monomers into the homogeneous polymerization could not increase the molecular weight because it was determined by the extent of reaction and reshuffled by the transamidation reaction. However, the addition of PPDA and IPA during the polymerization resulted in the increase in the molecular weight of PPIA. This result gave possibly a novel procedure for the preparation of high molecular weight condensation-type polymers.

DOI： 10.1021/ma9009033

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Preparation of poly(4'-oxy-4-biphenylcarbonyl) (POBP) needlelike crystals was examined by using reaction-induced crystallization of oligomers during copolymerization of 4-(4-aceloxypheilyl)benzoic acid (APBA) and 4-acetoxybenzoic acid (ABA). Polymerizations were carried out in aromatic solvent at various ABA molar ratios in feed (chi(f)). When they chi(f) was 20-10 mol %, starlike aggregates of needlelike crystals and fibrillated slablike crystals were separately formed, exhibiting similar morphology to poly(4-oxybenzoyl) and POPB crystals. 4-(Oxyphenyl)benzoyl (OPB) homo-oligomers and co-oligomers rich in OPB moiety were more rapidly precipitated due to the lower solubility, and the slablike crystals were formed. Afterward, 4-oxybenzoyl (013) homo-oligomers and the co-oligomers rich in OB moiety were precipitated to form spindlelike crystals. The OPB homo-oligomers and the co-oligomers rich in OPB moiety were continuously crystallized on both crystals due to the high degree of supersaturation. and the spindlelike crystals grew to the needlelike crystals mainly comprised of POBP. Copolymerization of 4-(4-acetoxybenzoyloxy)benzoic acid and APBA at chi(f) of 10 mol % yielded the needlelike crystals without coexisting fibrillated slablike crystals. This result provides a new methodology for morphology control with the aid of copolymerization.

DOI： 10.1021/ma800029n

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The morphology of poly(4-phthalimide) (PPI) crystals was examined by using reaction-induced crystallization of oligomers during solution polymerization. Polymerizations of alkyl 4-aminophthalates such as I-ethyl 4-aminophthalate (1EAP), 2-ethyl 4-aminophthalate, 1-hexyl 4-aminophthalate, and 2-hexyl 4-aminophthalate were carried out at 330 degrees C in a mixture of isomers of dibenzyltoluene without stirring. Nanoscale PPI ribbons having smooth surface were formed by the polymerizations of these monomers. The ribbons prepared from 1EAP at a concentration of 2.0% for 24 h were averagely 12 mu m in length, 150 urn in width, and 8 nm in thickness, in which the molecular chains aligned along the long axis of the ribbon. The phase-separated oligomers were fully cyclized imide oligomers, and this is of great importance for the formation of the ribbon. The obtained ribbons possessed high crystallinity and exhibited excellent thermal stability.

DOI： 10.1021/ma800874w

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Morphology control of polybenzimidazoles was examined by reaction-induced phase separation during polymerization. Polymerizations of 3,3'-diaminobenzidine with terephthalic acid or diphenyl terephthalate were carried out in poor solvents. The morphology of the precipitated poly[2,2'-(1,4-phenylene)-5,5'-bibenzimidazole] (PpBBI) was significantly influenced by the polymerization conditions, and the aggregates of nano-scale PpBBl fibers were obtained by the polymerization at a concentration of 3-5% and 320-350 degrees C in dibenzyltoluene. The average diameter of the fibers was ca. 50 mn and inherent viscosities of the precipitates were 0.35-0.58 dL g(-1). They possessed high crystallinity and thermal stability. The oligomers were precipitated first by the reaction-induced crystallization to form the highly crystalline lath-like crystals at an initial stage of polymerization. Then the lath-like crystals were split into disentangled aggregates of fine fibers with maintaining the high crystallinity. The polymerization mainly proceeded when the oligomers were registered into the crystals. The obtained aggregates of nano-scale fibers could be recognized as nonwoven fabrics. Morphology control of poly [2,2'-(1,3-phenylene)-5,5'-bibenzimidazole] was also examined and particles were mainly formed. (c) 2008 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2008.02.016

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER TOKYO  

We have designed a new type of retinal prosthesis using polyethylene films coupled with photoelectric dye molecules that absorb light and convert photon energy to electric potentials. An extruded-blown film of high-density polyethylene was used as the original polyethylene film. Recrystallized film was made by recrystallization from the melting of the original polyethylene film. A photoelectric dye,2-[2-[4-(dibutylamino)phenyl]ethenyl]-3-carboxymethylbenzothiazolium bromide, was coupled to the two types of polyethylene films through amide linkages. Samples of the original dye-coupled film, the dye-coupled recrystallized film, and the dye-uncoupled plain film were implanted in the subretinal space of normal adult rats. Frozen sections were cut from the eyes enucleated at 1 week or 1 month and were either stained with hematoxylin and eosin, stained immunohistochemically for glial fibrillary acidic protein (GFAP), or processed for in situ apoptosis detection. The results revealed that retinal tissue damage was negligible with no inflammatory cells and few apoptotic cells. GFAP was significantly up-regulated in retinal sites with the implantation of all types of polyethylene films at 1 week, compared with the adjacent retinal sites (P < 0.005, analysis of variance). The GFAP up-regulation was also present at 1 month for the plain film and dye-coupled recrystallized film (P < 0.05). Glial cell encirclement around the films increased significantly between 1 week and 1 month (P = 0.023, two-factor analysis of variance) but was not significantly different among the three types of polyethylene films (P = 0.4531). These results showed evidence of glial reactions to the photoelectric dye-coupled polyethylene films implanted into the subretinal space of rat eyes and also proved their basic biological safety.

DOI： 10.1007/s10047-007-0398-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Morphologies of poly(p-phenylene pyromelliteimide) (PPPI) were investigated by using phase separation during polymerization of pyromellitic dianhydride (PMDA) and p-phenylene diamine (PPDA). Polymerizations were carried out at 330 degrees C for 6 h. PPDA was added to the solution of PMDA in an aromatic solvent at various temperatures after PMDA was entirely dissolved. The morphology of the precipitates was drastically changed with the temperature of PPDA addition (Tad). When Tad was 240 degrees C, the fine particles were formed through the formation of droplets via liquid-liquid phase separation. On the contrary, when Tad was higher than 280 degrees C, the mixture of lozenge-shaped crystals and starlike aggregates of needlelike crystals were formed by the crystallization of oligomers. Tad influenced the degree of imidization of oligomers, resulting in the variation in the morphology of PPPI. Crystal structure and molecular chain orientation of the lozenge-shaped crystals were also investigated by high-resolution transmission electron microscope.

DOI： 10.1021/ma062032y

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Light illumination of single-wall carbon nanotubes (SWCNTs) dispersed with anthracene (An) dendrons afforded the accumulation of the reduced form of methyl viologen in the presence of a hole shifter. With the helps of the fluorescence lifetime and transient absorption measurements, the charge-separation process from the excited state of the hybrides of An dendrimer to SWCNT was confirmed.

DOI： 10.1246/cl.2006.1188

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY  

Photoelectric dyes, which absorb light and convert photon energy to electric potentials, were shown to stimulate retinal neurons in culture. One of these dyes coupled with polyethylene film surface, as a prototype of retinal prostheses, could induce intracellular calcium elevation in chick embryonic retinal tissues. In this study, we used retinal cells from chick embryos in which no photoreceptor outer segments yet developed, and assessed cell adhesiveness and response to the original and modified types of our retinal prostheses. Extruded-blown film of high density polyethylene was used as the original polyethylene film. Polyethylene film surface was modified either by coupling with type 1 collagen or by crystallization from the melt of the original polyethylene film. A photoelectric dye, 2-[2-[4-(dibutylamino)phenyl]ethenyl]-3-carboxymethylbenzothiazolium bromide, was coupled to these different types of polyethylene films through amide linkage. Retinal cells from chick embryos at the 12-day embryonic stage were cultured on the surface of dye-coupled films. The response of retinal cells to the dye-coupled films was observed by calcium imaging. Cell types, either neurons or glial cells, were detected by immunocytochemical staining and also observed by scanning electron microscopy (SEM). Intracellular calcium elevation was observed in cells, including both neurons and glial cells, on the surface of the original dye-coupled film, collagen-coated dye-coupled film, and dye-coupled recrystallized film, in contrast with no response of cells cultured on the dye-uncoupled plain film. Retinal neurons grew upon colonies of glial cells settling on the surface of all different types of the films. The number of retinal neurons on the collagen-coated dye-coupled film and dye-coupled recrystallized film was significantly larger than the number of neurons on the dye-uncoupled plain film (P = 0.0004, analysis of variance; P < 0.05, Tukey-Kramer test). With SEM, Muller cell-like large cells covered the original dye-coupled film and collagen-coated dye-coupled film, while neuron-like small cells settled directly on the dye-coupled recrystallized film and also formed large colonies on Muller-like cells. Retinal neurons and glial cells were cultured directly on the different types of dye-coupled polyethylene films. Photoelectric dye-coupled polyethylene films could be used as prototypes of retinal prostheses.

DOI： 10.1111/j.1525-1594.2006.00286.x

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Two types of morphologies have been observed in vapor grown carbon nano fibers (CNFs) using transmission electron microscopy (TEM). In one case, a truncated cone microstructure was observed, with outer and inner diameters of 60 and 25 nm, respectively. In this type of CNF, graphite sheets were oriented at about 15 degrees to the fiber axis. The second type of fiber was a double-layer CNF with outer and inner diameters of 83 and 20 nm, respectively. A truncated cone structure was also observed in the double-layer CNF. Graphite sheets in the outer layer of the double-layer fibers were oriented along the nano fiber axis. Tensile modulus for the first type of nano fiber along its axis was calculated to be 50 GPa, and for the second type of fiber the calculated modulus value was in the 100-775 GPa range, depending on the outer layer orientation. Modulus calculations based on these two morphologies explain the wide ranging experimental CNF modulus values reported in the literature.

DOI： 10.1007/s10853-006-0324-0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

The electrooxidation of alcohols in an aqueous disperse system with N-oxyl-immobilized poly(p-phenylene benzobisthiazole) network polymer particles (PBZT(NT)-N-Oxyl) as a disperse phase was performed successfully in a simple beaker-type undivided cell tinder a constant current condition to afford the corresponding ketones, aldehydes, and/or carboxylic acid in moderate to good yields. Recycle use of both the PBZT(NT)-N-Oxyl particles and the aqueous media could be achieved successfully by immobilization of additional N-oxyl moiety on the polymer particles in an appropriate interval. Notably, the shape and the particle size of PBZT(NT)-N-Oxyl were not appreciably changed even after 60 times recycle use. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.tet.2006.03.020

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MARY ANN LIEBERT INC  

To search for the mechanism of the effect of trehalose on the ocular surface applied as eye drops, we observed trehalose-treated and dried corneal epithelial surfaces of porcine eyes with atomic force microscopy. Full-thickness corneal pieces, 5 × 5 mm in size, were cut out from enucleated porcine eyes. Three kinds of disaccharides, trehalose, maltose, and sucrose, dissolved in saline at 100 mM concentration, and saline as a control, were applied to the epithelial surface of the full-thickness corneal pieces for 1 min. Excess fluid was then absorbed by cotton tips at the epithelial edge of the pieces, and the corneal pieces were dried naturally at room temperature and in room humidity for 72 h. The dried corneal epithelial surfaces were observed first with a dissecting microscope and then fixed on the observation platform for atomic force microscopy. With dissecting microscopy, trehalose-treated corneal epithelial surfaces appeared smoother than saline-, maltose-, or sucrose-treated surfaces. With atomic force microscopy in a tapping mode, saline-, maltose-, and sucrose-treated corneal epithelial surfaces had a larger number of pits in greater sizes than trehalose-treated surfaces. The number of pits measuring 0.14 μm or larger was significantly less in trehalose-treated corneal epithelial surfaces than in saline-treated surfaces (p = 0.0326, analysis of variance [ANOVA], p &lt
0.05, Tukey-Kramer test). No significant difference was found in the number of pits between maltose- or sucrose-treated surfaces and saline-treated surfaces. Mean roughness, an indicator for surface roughness, was significantly lower in trehalose-treated surfaces than in sucrose-treated surfaces (p = 0.0181, ANOVA, p &lt
0.05, Tukey-Kramer test). Trehalose-treated corneal epithelial surfaces are smoother than saline-, maltose-, or sucrose-treated surfaces. One effect of trehalose on the ocular surface is to keep the corneal epithelial surface smooth in drying condition. © Mary Ann Liebert, Inc.

DOI： 10.1089/cpt.2006.4.117

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CHEMICAL SOC JAPAN  

Single-walled carbon nanotubes (SWNTs) were well dispersed in both water and organic solvent by the use of fullero-dendron as a dispersant. A C-60 moiety at the focal point of dendron plays a crucial role in the dispersing process, because dendron having an anthracene unit at the focal point can not disperse SWNTs in THE The dispersions of SWNTs were characterized by UV-vis-NIR spectroscopy, Raman spectroscopy, SEM, HRTEM, and AFM.

DOI： 10.1246/cl.2005.1608

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

Dispersion and exfoliation of single wall carbon nanotubes (SWNTs) have been studied in poly(acrylonitrile) (PAN), poly(p-phenylene benzobisoxazole) (PBO) solutions, and composite fibers using transmission electron microscopy. As a result of polymer assisted dispersion and exfoliation, the average SWNT bundle diameter in SWNT/ PAN (5/95) was 11 nm, while the average diameter for the pristine SWNT bundles was about 30 nm. High resolution TEM of SWNT/PBO (10/90) composite fibers did not reveal the presence of SWNT aggregates or bundles, suggesting SWNT exfoliation as individuals. On the other hand, both oriented and unoriented nanotube bundles have been observed in SWNT/PBO samples containing 15 wt % nanotubes. Carbon nanotubes are 10(5) times more radiation resistant than flexible polymers such as polyethylene, and 10(5) times more resistant than highly radiation resistant polymers such as PBO. Therefore in the high resolution TEM study of nanotube/polymer composites, nanotubes can be observed long after the polymer has been damaged by electron radiation. (c) 2005 Wiley Periodicals, Inc.

DOI： 10.1002/app.22203

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Language：English   Publisher：ELSEVIER SCI LTD  

Polyacrylonitrile (PAN)/carbon nanotubes (CNTs) composite fibers were spun from solutions in dimethyl acetamide (DMAc), using single wall (SWNTs), double wall (DWNTs), multi wall (MWNTs) carbon nanotubes, and vapor grown carbon nanofibers (VGCNFs). In each case, CNT content was 5 wt% with respect to the polymer. Structure, morphology, and properties of the composite fibers have been characterized using X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy, tensile tests, dynamic mechanical tests, as well as thermal shrinkage. While all nanotubes contributed to property improvements, maximum increase in modulus (75%) and reduction in thermal shrinkage (up to 50%) was observed in the SWNT containing composites, and the maximum improvement in tensile strength (70%), strain to failure (110%), and work of rupture (230%) was observed in the MWNTs containing composites. PAN orientation is higher in the composite fiber (orientation factor up to 0.62) than in the control PAN fiber (orientation factor 0.52), and the PAN crystallite size in the composite fiber is up to 35% larger than in the control PAN (3.7 nm), while the overall PAN crystallinity diminished slightly. Nanotube orientation in the composite fibers is significantly higher (0.98 for SWNTs, 0.88 for DWNTs, and 0.91 for MWNTs and VGCNFs) than the PAN orientation (0.52-0.62). Improvement in low strain properties (modulus and shrinkage) was attributed to PAN interaction with the nanotube, while the improvement in high strain properties (tensile strength, elongation to break, and work of rupture) at least in part is attributed to the nanotube length. Property improvements have been analyzed in terms of nanotube surface area and orientation. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2005.08.092

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPANDIDOS PUBL LTD  

We developed a new hybrid gel phantom using carrageenan and gellan gum for the purpose of visualizing three-dimensional temperature distribution. The phantom, which contains carrageenan, gellan gum, non-ionic surface active agent, potassium chloride, n-butanol, sodium azide, and water, shows good transparency at room temperature, and has the advantage that the heated region becomes white and opaque due to segregation of the surface active agent. Carrageenan and gellan gum were added to improve the transparency and fragility of the hybrid gel. Potassium chloride was used to adjust the electrical conductivity of the gel to a range of 5-130 MHz, so that it would be equivalent to that of muscle tissue for each frequency used by electromagnetic heating devices. N-butanol was used to adjust the clouding temperature to a range between 45 and 55 degrees C. In the present study we clarified the important properties of the new phantom, and developed formulae for easy determination of the amounts of ingredients necessary for the desired clouding temperature and electric conductivity. The characteristics of this phantom are: a) a solid form to avoid convection by heat conduction; b) sufficient strength without fragility to form a torso without the use of a reinforcing agent; c) high transparency at room temperature and visualization of the heating area as a white turbidity; d) time-lapse and accurate visualization of the changing temperature area without thermal hysteresis; e) electrical properties similar to those of human tissues; f) ease of production; and g) low cost and good safety. This phantom might assist oncologists in their routine checking and study of the performance of electromagnetic heating devices for hyperthermia and radiofrequency ablation.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

Single-walled carbon nanotube (SWNT)/ poly(methyl methacrylate) and SWNT/polyacrylonitrile composite nanofibers were electrospun with SWNT bundles as the cores and the polymers as the shells. This was a novel approach for processing core (carbon nanotube)-shell (polymer) nanofibers. Raman spectroscopy results show strain-induced intensity variations in the SWNT radial breathing mode and an upshift in the tangential (G) and overtone of the disorder (G') bands, suggesting compressive forces on the SWNTs in the electrospun composite fibers. Such fibers may find applications as conducting nanowires and as atomic force microscopy tips. (c) 2005 Wiley Periodicals, Inc.

DOI： 10.1002/app.21662

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS INC  

Polymerization of 4-acetoxybenzoic acid (ABA) with 3,5-diacetoxybenzoic acid (DABA) was examined to control the morphology of poly(p-oxybenzoyl) (POB). Polymerizations were carried out at a concentration of 1.0% in an aromatic solvent Therm S-1000 (R) (mixture of dibenzyltoluene) at 320 degrees C. Polymerization of ABA yielded the POB fibrillar crystals, but the polymerization with DABA at a concentration in the feed (chi(f)) of 0.10-0.15 afforded novel network structures comprised of spheres connected by fibrillar crystals. The diameter of the spheres prepared at chi(f) of 0. 15, which were 0. 7 and 5.0 mu m, showed bimodality. The network distance, fibril length, and fibril width were 6.1, 2.6, and 0.1 mu m, respectively. They possessed high crystallinity. The network structure was formed as follows. Co-oligomers were first precipitated in the beginning of the polymerization by liquid-liquid phase separation to form the microdroplets. The fibrillar crystals were formed in the coalesced spheres by the crystallization of oligomers induced by the increase of molecular weight. The fibrillar crystals connecting the spheres gradually appeared owing to the shrinkage of the spheres. The fibrillar crystals grew from the surface of the spheres with the crystallization of homo-oligomers of 4-oxybenzoyl units, and finally the network structure was completed. (c) 2005 Wiley Periodicals, Inc.

DOI： 10.1002/pola.20639

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

Preparation of polymer whisker based on p-mercaptobenzoyl (S) and p-oxybenzoyl (0) blocks was examined by the polymerization of Sacetyl-4-mercaptobenzoic acid (AMBA) and the following addition of 4-acetoxybenzoic acid (ABA). Polymerization of AMBA was carried out in liquid paraffin at 300 degrees C for 3 h yielding poly(p-mercaptobenzoyl) (PMB) whisker, and then ABA was added stepwise at 3-hour intervals into the solution. Initial polymerization concentration was 1.98%. The length of the whisker increased with the addition and it became 26.7 mu m from 20.1 mu m after third ABA addition. The width increased very slightly. Both length and width increased with polymer yield but the length increased preferentially rather than the width. The number of whiskers was constant even after the addition of ABA and poly (p-oxybenzoyl) (POB) whisker was not newly formed by the addition. Microscopic FT-IR and selected area electron diffraction measurements revealed that polymer molecules were aligned along the long axis of the whiskers, and the center and tip parts were comprised of PMB crystal and POB crystal, respectively. The polymer whisker based on S and 0 blocks was successfully prepared as grafting POB crystal on PMB whisker with stepwise addition of ABA. Thermal property of the resulting whiskers was also discussed. (c) 2005 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2005.01.016

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS LTD  

Direct synthesis of poly(4'-oxy-4-biphenylcarbonyl) (POBP) and poly(2-oxy-6-naphthoyl) (PON) was examined by polycondensation of 4'-hydroxy-4-biphenylcarboxylic acid (HBPA) and 2-hydroxy-6-naphthoic acid (HNA) in the presence of 4-ethoxybenzoic anhydride or 2-naphthoic anhydride as condensation reagents. Polymerizations were carried out at 320degreesC in aromatic solvents and liquid paraffin. POBP, having a number-average degree of polymerization (DPn) of 38, was obtained as plate-like crystals at the molar ratio of HBPA and anhydride of 50 mol%. PON was also obtained as plate-like crystals but the DPn was only 13. HBPA and HNA were first converted to reactive acyloxyaromatic acid intermediates. Then the DPn was increased by means of reaction-induced crystallization of oligomers and subsequent solid-state polymerization via an acid-ester exchange under nonstoichiometric conditions caused by the monocarboxylic acid by-product. Even though the DPn of PON was not as high, direct polycondensation of HBPA and HNA proceeded successfully with aromatic anhydrides. (C) 2004 Society of Chemical Industry.

DOI： 10.1002/pi.1728

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS LTD  

Solvent effect on the morphology of poly(p-oxybenzoyl) (POB) prepared by the reaction-induced phase separation of oligomers was examined by the polymerization of p-acetoxybenzoic acid in perfluoropolyether Aflunox(TM) (AFL2507 and AFL606). Polymerization was carried out at 320degreesC for 6 hr. POB microspheres were formed in AFL2507 by the liquid-liquid phase separation of oligomers due to the low miscibility of oligomers in AFL2507. The molecular weight of the solvent influenced the morphology, and the polymerization in AFL606 of which the molecular weight was lower than AFL2507 yielded whiskers formed by crystallization of oligomers induced by the increase in miscibility compared with that in AFL2507. The solvent structure and its molecular weight influenced the miscibility of oligomers and ultimately controlled the morphology from whisker to microsphere. Copyright (C) 2004 John Wiley Sons, Ltd.

DOI： 10.1002/pat.540

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：VSP BV-C/O BRILL ACAD PUBL  

Rigid-rod polymeric fibers, fabricated from their lyotropic mesophase in strong acid solutions, are known to have exceptional tensile strength and high stiffness besides exhibiting remarkable thermal and thermooxidative stabilities. Mechanical and electrical properties of Single-Wall Carbon Nanotubes (SWNTs) are also predicted to be quite extraordinary. The potential benefits of reinforcing a rigid-rod polymer, such as P130, with SWNTs as the dispersed phase are demonstrated in this study. The general methodology involves in situ polycondensation to form the rigid-rod polymer in polyphosphoric acid medium in an environment of SWNTs, followed by the dry-jet wet spinning of the hybrid fibers from the lyotropic liquid crystalline solution. The tensile strength of the PBO/SVv'NT fibers incorporating 10 wt% SWNT was found to be 50% higher than that of the control P130 fibers, while only relatively moderate enhancements in the measured values of the tensile modulus and compressive strengths resulted for the hybrid fibers. Morphological studies of the fibers by TEM analysis showed that SWNTs were very well-dispersed in the 90/10 PBO/SWNT heat-treated composite fibers but the presence of SWNT bundles or ropes, 20-50 nm diameter, aligned parallel to the fiber axis, was observed at higher levels of incorporation of SWNTs as was indeed the case for 85/15 PBO/SWNT heat-treated fibers. Recent efforts to effect the sidewall modification of SWNT with phenylbenziraidazole groups to enhance the potential for SWNT dispersion/solubility in acidic media are also discussed.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

The poly(p-phenylene benzobisthiazole) (PBZT)/carbon nano fiber (CNF) composite was prepared by in situ polymerization in polyphosphoric acid (PPA), and fibers spun by dry-jet wet spinning. The liquid crystalline PBZT/CNF dope in PPA exhibited excellent spinnability. The PBZT/CNF weight ratio was 90/10. The transmission electron microscope images show isolated and well oriented CNFs with no aggregation. CNF graphite layer stacking in the composite fiber have been observed using high resolution transmission electron microscopy, and showed that graphitic structure of CNFs was not damaged during polymerization in PPA and subsequent fiber spinning and drawing. High resolution transmission electron microscopy also shows that there is no debonding between CNF and the PBZT matrix. Tensile and compressive properties of the composite fibers have been determined and discussed. (c) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.compsitesb.2004.04.015

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SOC POLYMER SCIENCE JAPAN  

Influence of acyl end-group of oligomers on morphology of poly (p-mercaptobenzoyl) (PMB) was examined by the polymerization of S-acyl-4-mercaptobenzoic acids having the different acyl groups and their dimers in liquid paraffin at 260-300 degrees C. The polymerization of S-acetyl-4-mercaptobenzoic acid afforded PMB whiskers, whereas the polymerization of S-propionyl-4-mercaptobenzoic acid, S-butyryl-4-mercaptobenzoic acid and S-valeryl-4-mercaptobenzoic acid yielded PMB microspheres. The microspheres were formed by the liquid-liquid phase separation of oligomers induced by the longer acyl end-groups than acetyl group of the oligomers due to the reduction of freezing point of oligomers. In contrast to this, the polymerizations of their dimers afforded needle-like and slab-like crystals instead of microspheres. In these polymerizations, the crystallization was induced due to the increase of the molecular weight of the phase-separated oligomers, leading to the increase of the freezing point of oligomers. The morphology of PMB could be controlled by the chemical modification of oligomer end-groups.

DOI： 10.1295/polymj.37.471

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

PAN/SWNT composite fibers have been spun with 0, 5, and 10wt% single wall carbon nanotubes (SWNTs). Tensile fracture surfaces of polyacrylonitrile (PAN) fibers exhibited extensive fibrillation, while for PAN/SWNT composite fibers, tendency to fibrillate decreased with increasing SWNT content. The reinforcing effect of SWNTs on the oxidized polyacrylonitrile (PAN) fiber has been studied. At 10wt% SWNTs, breaking strength, modulus, and strain to failure of the oxidized composite fiber increased by 100%, 160%, and 115%, respectively. Tensile fracture surfaces of thermally stabilized PAN and the PAN/SWNT fibers exhibited brittle behavior and well distributed SWNT ropes covered with the oxidized matrix can be observed in the tensile fracture surfaces of the fibers. No de-bonding has been observed between unoxidized or the oxidized PAN matrix and the nanotube ropes. Higher strain to failure of the oxidized composite fiber as compared to that of the oxidized control PAN fiber also suggests good adhesion/interaction between SWNT and the oxidized matrix. Thermal stresses generated on the composite fiber during the oxidation process were lower than those for the control fiber. The potential of PAN/SWNT composite fiber as the precursor material for the carbon fiber has been discussed. (C) 2004 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbon.2004.10.034

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DOI： 10.1201/9780203491966

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

The crystal structure in random copolymers poly(ethylene terephthalate-co-4,4'-bibenzoate) (PET/BB) was studied using wide-angle X-ray diffraction (WAXD). The composition of crystalline and amorphous regions has been studied by FTIR spectroscopy using the amorphous peaks at 1580 and 1560 cm(-1) for terephthalate (T) and bibenzoate (B) units, respectively. Further, PET/BB55 was hydrolyzed to selectively etch the amorphous regions. The hydrolyzed products were further studied by FTIR and H-1 NMR spectroscopy, wide-angle X-ray diffraction, and transmission electron microscopy. Results show that crystal structures are very close to that of the respective homopolymer, PET and poly(ethylene bibenzoate) (PEBB) for the low and high BB content samples, respectively. The crystalline region of high BB content fibers is composed of mainly PEBB units. In PET/BB55 fiber, among the 30 wt % of the copolymer which was not etched, there is only one terephthalate unit for every five repeat units of bibenzoate. The crystal size of B type crystals along the c axis was found to be around five repeat units long. Short chain segments rich in BB are sufficient to induce crystallization, to form PEBB-like crystals.

DOI： 10.1021/ma0486905

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MARCEL DEKKER INC  

Fractionation of the rigid polymer, poly(p-phenylene benzobisthiazole) (PBZT), was carried out in dilute solution in concentrated methane sulfuric acid (MSA) using silica gels as packing material of a column. Several combinations of the average chain length of the fractionating materials and the average pore diameter of the gels were examined to improve fractionation resolution. The gels with average pore diameter near the average chain length resulted in high fractionation resolution. Single crystals of the fractionated and unfractionated PBZTs were observed by transmission electron microscopy (TEM). Both single crystals were fundamentally composed of rod crystals with the chain orienting normal to the rods. The unfractionated PBZT made a cluster of parallel rod crystals, where longer chains penetrated a few rod crystals leaving their chain ends within the crystalline core. On the contrary, with the fractionated polymer, extended-chain rod-like crystals were dispersed, isolated from each other. This morphology enables us to estimate the chain length visibly by TEM, for which a few milligrams of the material is enough for the observation.

DOI： 10.1081/MB-200033280

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Polymerization of 4-acetoxybenzoic acid (ABA) with 3,5-diacetoxybenzoic acid (DABA) was examined to create a novel morphology of poly(p-oxybenzoyl) (POB) by means of the phase separation of oligomers during polymerization. Polymerizations were carried out at a concentration of 1.0% in liquid paraffin at 320 degreesC. Polymerization of ABA yielded the POB whiskers. On the other hand, the polymerization of ABA with DABA of which the concentration in the feed (chi(f)) was 0.05-0.20 yielded the microspheres having needlelike crystals on the surface. The average diameter of the microspheres was in the range of 3.4-1.6 mum and the average length of the needlelike crystals was 3.2-0.3 mum. The diameter and length decreased with chi(f). DABA acted as a liquid-liquid phase separation inducer and the liquid-liquid phase separation of co-oligomers comprising 4-oxybenzoyl units and 3,5-dioxybenzoyl units was induced in the beginning of polymerization to form the core microspheres. Then the phase separation mode was changed to the crystallization of the homooligomers of the 4-oxybenzoyl unit and the homooligomers were crystallized as needlelike crystals on the surface of microspheres already precipitated. Solid-state polymerization occurred in the precipitates. The microspheres having needlelike crystals were prepared by the combination of liquid-liquid phase separation and the crystallization of oligomers during solution polymerization. The obtained microspheres having needlelike crystals possessed very high crystallinity and exhibited good thermal stability.

DOI： 10.1021/ma035672z

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

The diameter control of poly(p-oxycinnamoyl) (POC) microspheres was examined. POC microspheres were prepared by the polycondensation of (E)-4-acetoxycinnamic acid in liquid paraffin at 320 degreesC. The microspheres were formed through the formation of microdroplets by the reaction-induced liquid-liquid phase separation and the subsequent polymerization of oligomers in the microdroplets leading to the solidification. The size of the microspheres was actually governed by the coalescence of the microdroplets in the growth process. In order to control the coalescence of the microdroplets, 4-octadecyloxybiphenyl (ODB) was added to the polymerization solution as a coalescence inhibitor, which exhibited amphiphilicity to liquid paraffin and POC. ODB inhibited the coalescence of the microdroplets. The average diameter decreased with the increase of the ODB concentration, and it was tunable from 0.97 to 4.61 mum. (C) 2003 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2003.08.042

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：SOC FIBER SCIENCE TECHNOLOGY  

Rigid polymer networks were prepared by polycondensation of 2,5-diamino-1,4-benzenedithiol with a mixture of tereplithalic acid (TPA) and trimesic acid (TMA). The apparent density was dependent on TPA/TMA ratio and much less than that of linear PBZT (1.57 g/cm(3)), showing existence of many nano voids within the network. As the segment was so rigid, many COOH's were left around the voids. The network swelled twice in weight with E caprolactam, which was polymerized into a composite form of nylon6 impregnated rigid polymer network. Extraction of free nylon6 from the composite with formic acid showed that a quarter of nylon6 grafted directly to rigid polymer network. The grafted nylon6 could not crystallize evidenced by DSC measurements. On the other hand, particles of PBZT network (several hundred nm in diameter) were prepared by stopping the polycondensation just before gelation. A composite film was prepared with the particles swollen with epsilon-caprolactam. The ratio of PBZT network/nylon6 was 1/3 and the apparent density of the composite film was 1.23 g/cm(3) which is higher than that of a pure nylon6 film (1.16 g/cm(3)). Significant improvement in the mechanical property was observed for this composite.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER CHEMICAL SOC  

Self-assembling polycondensation was examined to prepare the whisker of poly(p-oxybenzoyl-alt-p-mereaptobenzoyl). Polymerizations were carried out in liquid paraffin (LPF) and aromatic solvents such as Therm S 800 and 1000 at 300 degreesC for 6 h. Polymerization concentration was 1.0 wt/vol %. The whisker was not obtained by the random copolymerization of p-acetoxybenzoic acid and S-acetyl-4-mercaptobenzoic acid at the molar ratio of 0.5 in feed. However, the whiskers were successfully prepared by the polymerization of S-(4-acetoxybenzoyl)-4-mercaptobenzoic acid (OS) and 4-(S-acetyl-4-mercaptobenzoyl)oxybenzoic acid (SO). The whisker prepared from OS (POS) in LPF was 18 mum in average length and 0.4 mum in average width, and that from SO (PSO) was slightly longer than POS. The whiskers prepared in aromatic solvents were much longer than those in LPF, for which the length was 36-49 mum. These whiskers consist of the alternating polymer chains, and the polymer chains align along the long axis of the whisker. The sequence regularity enhanced the crystallizability of the oligomers, and this led to the formation of whiskers. The oligomer formation rate was much higher than that of transesterfication reaction rate, and this large difference in these two rates made the oligomer precipitate with maintaining the alternating sequence. Further polymerization occurred in the crystals, and the whiskers having the alternating sequence were finally completed. The difference in the two rates increased with the decrease of the miscibility between the oligomer and the solvent, and therefore, OS and LPF were more advantageous to maintain the alternating sequence.

DOI： 10.1021/ma030046n

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：GEORG THIEME VERLAG KG  

Electrooxidation of alcohols was performed successfully in a disperse system with N-oxyl immobilized polyethylene particles as disperse phase and an aqueous saturated NaHCO3 solution involving 20 wt% NaBr as disperse media. The N-oxyl immobilized polyethylene particles were prepared by heating a suspension of polyethylene particles (3 x 3 x 0.02 mm(3)) in fuming nitric acid at 80 degreesC for 1 h followed by treatment with 4-amino-2,2,6,6-tetramethylpyperidine- 1-oxyl in chlorobenzene in the presence of DCC. Recycle use of the N-oxyl-immobilized polyethylene particles and the aqueous media was performed successfully without significant change of the yields of the products and current efficiency, thereby offering a totally closed electrolysis system.

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DOI： 10.2115/fiber.59.207

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS LTD  

Poly(ethylene-block-vinylalcohol) (PE/PVA), which consisted of both hydrophobic and hydrophilic blocks, was prepared by using polyethylene single crystals as starting material. Polyethylene single crystals were reacted with fuming nitric acid resulting in long methylene chains with functional groups such as COOH and NO? at the ends (the chain lengths were almost the same as the lamellar thickness of polyethylene single crystal). The functionalized methylene chains were allowed to react with 4-aminostyrene to give corresponding amides, i.e. methylene chains with vinyl groups at the ends (macromer). The macromers were extended by block-copolymerization with vinyl acetate, then saponified resulting in PE/PVA block copolymer.
The block copolymer was molded into sheets which were subsequently heat-treated in contact with hydrophilic or hydrophilic media. Depending on the media, the sheet surface changed at high temperature reversibly from hydrophilic to hydrophobic and vice versa. Die surface property was fixed by quenching because both blocks were able to crystallize. Thus the surface of this material can be tailored for various purposes at high temperature, and then used in stable condition at room temperature. Copyright (C) 2002 John Wiley Sons, Ltd.

DOI： 10.1002/pat.174

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MARCEL DEKKER INC  

The rigid polymer, poly(p-phenylene benzobisthiazole), crystallized from H2SO4, formed a lamellar crystal in which the polymer chains were oriented perpendicular to the lamellae. It was supposed that the lamellar surface bristled with chain cilia because of wide distribution in the polymer chain length. This region of the bristle would be a transitional structure from full to deficient packing of the polymer chains. Ordinary scanning probe microscopy of the bristled lamellar surface permitted depiction of a layer with a constant population of the cilia. In this work, the method for imaging one single polymer chain end standing on the lamellar surface was developed. From the image it was concluded that an isolated, long cilium did not move extensively at room temperature. In addition, the three-dimensional chain end distribution was determined by several tens of scannings with consecutively varying input energy of the cantilever.

DOI： 10.1081/MB-120004351

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELECTROCHEMICAL SOCIETY INC  

Electrooxidation of alcohols 1 was performed successfully in an aqueous disperse system with N-Oxyl-immobilized polyethylene particles (PE-N-Oxyl) as the disperse phase and an aqueous saturated NaHCO3 containing 20 wt.% of NaBr as the disperse media. Work-up process is quite simple; thus, polymer perticles were separated by filtration and washing with EtOAc and the filtrate and the washings were combined, extracted with EtOAc, dried (Na2SO4) and concentrated in vacuo to afford the corresponding ketones 2. The recovered PE-N-Oxyl as well as the aqueous disperse media could be repeatedly used for the electrooxidation of 1 without significant change of the yields of the ketones 2.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JOHN WILEY & SONS LTD  

Aromatic polymers are expected to possess outstanding properties. However in many cases they do not show good processability because of their chain regidity. We have been studying the morphology control of rigid polymers during polymerization to overcome this problem and succeeded in preparing the whiskers of poly (p-oxybenzoyl) and poly (p-mercaptobenzoyl) by the polymerization in liquid paraffin at around 300 degreesC. These whiskers are formed by the reaction induced crystallization of oligomers during solution polymerization.
The preparation of copolymer whiskers is very interesting to design the new materials which are endowed with novel functions. The aim of this study is to prepare the whisker of poly (p-oxybenzoyl-co-p-mercaptobenzoyl) and to clarify the influence of the copolymerization on the morphology, especially focusing on the sequence regularity. The introduction of comonomer unit into polymer chain structure extinguishes the crystal habit due to the lower crystallizability and the whiskers can be obtained by the random copolymerization of 4-acetoxybenzoic acid (ABA) and S-acetyl-4-mercaptobenzoic acid (AMBA) only when chi (f) (the molar ratio of ABA/AMBA in feed) is 1.0-0.7 and 0.05-0. However, the copolymer whiskers are obtained by the polymerization of OS, OOS and SSO monomers which produce the alternating and periodic copolymers. These copolymer whiskers consist of the alternating or periodic copolymer chains and their chains align along the long axis of the whisker. The sequence regularity enhances the crystal lizability of cooligomers and this lends to the formation of the whiskers. The sequence regularity in copolymers is a very influential parameter to control the morphology and the copolymer whiskers can be prepared by giving the regular sequences. Copyright (C) 2000 John Wiley & Sons, Ltd.

DOI： 10.1002/1099-1581(200008/12)11:8/12<747::AID-PAT53>3.0.CO;2-4

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：John Wiley &amp; Sons Ltd  

The structure of a wholly aromatic copolyester fiber containing 60 mol% p-hydroxybenzoic acid (PHB), 20 mol% 4-4'-dihydroxydiphenyl, 15 mol% terephthalic acid and 5 mol% isophthalic acid was studied by means of electron microscopy and wide-angle X-ray diffraction. The X-ray diffraction pattern of the wholly aromatic copolyester fibers showed two sets of diffractions: one set was composed of sharp spots which arose from relatively high crystalline phase. The crystal structure analyzed by these spots was orthorhombic and the lattice dimensions were a = 0.869 nm, b = 0.510 nm, c = 1.20 nm and ρ = 1.50 g/cm3. Another set was characteristic of streaks on the meridian extending parallel to the equator. X-ray scattering intensity distribution on the meridian was calculated as the square of Fourier transform of random chain model. Comparison of this intensity distribution with the observed meridional maxima concluded that the streaks were due to rather disordered chains with a PHB content of less than 50%. Dark field image (DFI) taken from the meridional 002 reflection showed that slender crystallites were distributed over the whole visual field, oriented parallel to the fiber axis. On DFI from the equatorial 200 reflection, some of these crystallites were also observable, forming groups that distributed randomly in the field. All crystallites belonging to the same group co-oriented in a(*)- and c(*)-axis directions, though disordered parts intervened among the crystallites. This is attributed to the fact that, though the content of PHB in the segments of disordered parts was only 50%, these PHB held the co-orientation among the slender crystallites within one group. Heat treatment induced the development of block segment and subsequent crystallite growth with fiber. This reorganization improved the thermostability and the mechanical properties. Copyright (C) 2000 John Wiley and Sons, Ltd.

DOI： 10.1002/1099-1581(200004)11:4<198::AID-PAT970>3.0.CO;2-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MARCEL DEKKER INC  

The rigid polymer poly(p-phenylene benzobisthiazole) (PBZT) was crystallized from dilute solution. Electron microscopy showed that, on quenching, flat fibrils several nanometers thick were produced. Subsequent heat treatment in a solvent changed the morphology from fibrillar into "segmented ribbon" structure. Isothermal crystallization at a temperature of about 30 degreesC below the dissolution temperature, in general, resulted in aggregation of rod crystals. The polymer chains were oriented normal to the rod crystals. The width of the rod crystal increased with average molecular length, but saturated to a value much smaller than the average molecular length. In the shorter molecular length range, the rod crystals clustered in a fanned-out manner, while with a medium molecular length (ca. 70-120 nm), all rods crystals in a cluster aligned parallel to each other and were of the same length. With longer molecular length (more than ca. 180 nm), the rod growth slowed because of small diffusion constants of molecular chains to the growing face. Based on observation of the morphology and the crystallization process, an isothermal crystallization mechanism is proposed. Because of the rigidity and wide length distribution of polymer chains, the chain ends were inevitably included within the crystals, resulting in crystal defects such as axial shifts, lattice curvatures, and edge dislocations, all of which were observed directly by lattice imaging.

DOI： 10.1081/MB-100102478

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Language：Japanese   Publisher：The Society of Polymer Science, Japan  

Structure of the extruded-blown film of high density polyethylene was studied by X-ray diffraction, SEM, and SPM. Lamellar bundles were piled up along the extrusion direction and oriented perpendicular to the extrusion direction. Close observation by SPM revealed that one lamellar bundle which looked like a single lamella by SEM was actually composed of ca. 6 lamellae. We propose that formation of such lamellar bundles may be due to self-vibration by rubbing with a die during the extrusion of melt.

DOI： 10.1295/koron.56.828

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Language：English   Publishing type：Research paper (scientific journal)  

PBZO's having average molecular length of 27,49 and 128 nm were crystallized from dilute solution in conc.H2SO2. At high crystallization temperature, the shorter PBZO (L∼30nm) formed lath shaped lamellar crystals. Electron diffraction indicated that the long axis of the lamella to be along the crystallographic b-axis forming 100 twins, and that the molecular chains was perpendicular to the lamella. High resolution electron micrograph showed that 100 lattice fringe had an orientation distribution and curved within one crystallite. Decrease in crystallization temperature and/or increase in the chain length changed the morphology essentially into flat fibrils. Branchings through repetitive twinning across {100} and [formula-ommited] planes lead to a square network. Vacancies in the fibrillar network were finally filled by post lamellar growth resuting in a mosaic structure, except with PBZO of the longest molecular chain. Oriented rigid cilia on the lamellar surface facilitated the growth rate of daughter crystals and regulated their orientation. © 1998, The Society of Fiber Science and Technology, Japan. All rights reserved.

DOI： 10.2115/fiber.54.7_374

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Language：English   Publishing type：Research paper (scientific journal)  

Poly(p-phenylenebenzobisthiazole) P (PBZT) chains with average molecular length of 61 nm have been reacted with trimesic acid to link each other. The product, a mixture of Y-, V-shaped and linear P (PBZT)'s, was dissolved into conc.SCU at a concentration of 0.1 wt%, and isothermally crystallized. The precipitate was composed essentially of curved rod-like crystals. Four or five crystals having different length coagulated each other with many branches at an angle of ca 60°. This morphological feature was in contrast to that of pure linear P (PBZT) precipitate in which several tens straight rod-like crystals of the same length were oriented parallel to each other to make a group. This difference in morphology between linear P (PBZT) and the mixture of Y, and V-shaped and linear P (PBZT)'s was well explained by the crystallization mechanism of P (PBZT). 100 lattice fringe was observed throughout the central area of the rod-like crystal. This means that the center was composed of linear part of Y-, V-shaped and linear polymers, which were accomodated normal to the rod. In some area, the 001 lattice fringe crossed 100 lattice fringe at an angle of ca 75°, suggesting that P (PBZT) unit cell might not be Fratini's monoclinic type. On both sides of the 100 lattice fringe, there were dark belts. These belts corresponded to thick parts which were composed of the other counterparts in the Y- and V-shaped poly mers. © 1994, The Society of Fiber Science and Technology, Japan. All right reserved.

DOI： 10.2115/fiber.50.3_101

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Language：Japanese   Publisher：日本工業出版  

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Language：Japanese   Publisher：繊維社  

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Language：Japanese   Publisher：繊維社  

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Language：Japanese   Publisher：化学工業社  

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DOI： 10.4044/joma.127.223

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Language：Japanese   Publisher：化学工業社  

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DOI： 10.11392/jsao.43.189

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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DOI： 10.2115/fiber.67.P_132

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：Japanese  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publisher：Faculty of Engineering, Okayama University  

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Language：English   Publisher：CHEMICAL INDUSTRY PRESS  

Dispersion and exfoliation of single wall carbon nanotubes (SWNTs) have been studied in poly(acrylonitrile) (PAN), poly(p-phenylene benzobisoxazole) (PBO) solutions, and composite fibers using transmission electron microscopy. Close observation of the SWNT/PAN (5/95) composite fibers revealed that as a result of polymer assisted dispersion and exfoliation, the average SWNT bundle diameter in SWNT/PAN (5/95) was 11 nm, while the average diameter for the pristine SWNT bundles was about 30 nm. In addition, high resolution TEM of SWNT/PBO (10/90) composite fibers did not reveal the presence of SWNT aggregates or bundles, suggesting SWNT exfoliation as individuals. On the other hand, both oriented and unoriented nanotube bundles have been observed in SWNT/PBO samples containing 15 wt % nanotubes.

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Language：English   Publishing type：Research paper, summary (international conference)   Publisher：AMER CHEMICAL SOC  

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Language：English   Publisher：Faculty of Engineering, Okayama University  

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Other Link： http://eprints.lib.okayama-u.ac.jp/15350

Language：English   Publisher：Faculty of Engineering, Okayama University  

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Language：English   Publisher：Faculty of Engineering, Okayama University  

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Language：English   Publisher：Faculty of Engineering, Okayama University  

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Language：English   Publisher：MUNKSGAARD INT PUBL LTD  

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