Ryutoku Yosomiya

Synthesis, thermal properties, and biodegradability of propyl-etherified starch

High amylose corn starch (HACS) was etherified with 1-bromopropane in dimethyl sulfoxide. The structure of the products was characterized by infra-red and 1H-NMR spectroscopy. The degree of substitution (DS) on glucose unit calculated from 1H-NMR spectrum was varied from 0.9 to 2.7 by changing feed ratio of 1-bromopropane to HACS. Thermogravimetric analysis reveals that the etherified HACS has a higher decomposition temperature than unmodified HACS. Differential scanning calorimetry analysis reveals that the etherified starch has a clear glass transition temperature which decreased with increasing DS, and that no melting point is observed. This result demonstrates that the etherified HACS mainly consists of amorphous region. The biodegradation rate decreases with increasing degree of etherification.

Synthesis and properties of the block copolymers of poly(ether ether ketone) and the poly(aryl ether sulfone) containing biphenylene moiety

Abstract The block copolymers of poly(ether ether ketone) (PEEK) and poly(aryl ether sulfone) containing biphenylene moiety (PEBS) were synthesized by a condensation reaction of fluorine-terminated PEEK oligomers and hydroxy-terminated PEBS oligomers. The content of PEBS in the copolymers was varied from 10 to 37 wt%, and the effect of the compositional variation on the properties was investigated. Microphase separation was not observed and the copolymer was a homogeneous system having good compatibility. The crystal structure of the copolymers is rhombic, equal to PEEK. Although the degree of crystallinity of the copolymers decreased with the increase of PEBS content, the glass transition temperature (Tg) rose greatly, and superior heat resistance and good mechanical properties at high temperature were obtained. Analyses of the isothermal crystallization kinetics of the copolymers provided an Avramis exponent (n) of 2.0.

Photoconductive properties of TiO2 films prepared by the sol–gel method and its application

The Photoconductive characteristics of TiO2 films prepared by the sol-gel method, and the photovoltaic characteristics fabricated with the resulting TiO2 film and phthalocyanine nickel (NiPc) are investigated. For a TiO2 film with hydroxypropyl cellulose (Hpc) heat treated at 500°C for 10 min, the relative sensitivity is about ten times higher than that without Hpc. A space-charge-limited current is observed in the dark current–voltage characteristic of the TiO2 film with Hpc. It is found that the TiO2 film with Hpc has a photosensitizing effect. The photovoltaic characteristics of TiO2(Hpc)/NiPc are as follows: the short-circuit current density, Jsc is 5.6×10-7 A cm-2, the open-circuit voltage, Voc is 0.24 V, the fill factor (F.F) is 0.64 and the power conversion efficiency, η is 0.73. Furthermore, the carrier transport mechanisms of the TiO2(Hpc)/NiPc photovoltaic cell are discussed.

Chemical modification of pullulan by isocyanate compounds

Abstract The modified pullulan derivatives having N-phenylurethane and N-hexylurethane groups in the side-chain (PI-PL and HI-PL) have been synthesized by the reactions of pullulan with phenyl isocyanate (PIC) and hexyl isocyanate (HIC), respectively. The structure of the derivatives was characterized by gel permeation chromatography, IR and 1H NMR spectroscopy. From the measurement of differential scanning calorimetry of PI-PL and HI-PL with various degrees of addition (DA) in the range of 0–3, it was revealed that both the derivatives showed a clear glass transition temperature (Tg), which decreased with the increasing DA of PIC and HIC. The pullulan derivatives were water-resistant and had good solubility in general organic solvents.

Polymer electrolytes based on blends of poly(ether urethane) and polysiloxanes

Abstract Ionic conductivity of poly(ether urethane) (PEU)-based electrolyte increased up to 10 −5 S/cm at room temperature by blending polysiloxane (KF50) or polyether-modified polysiloxane (KF615A) with PEU. Although the PEU/KF615A blend was a compatible system, the PEU/KF50 blend showed a phase-separated morphology. From the analyses of glass transition temperature, dielectric constant and ion mobility, it was suggested that the improvement of the conductivity is attributed to the increase of ion mobility, which compensates for the decrease of ion density for the PEU/KF50 electrolyte and to the increase of both the ion mobility and ion density for the PEU/KF615A electrolyte.

Facile synthesis of phenyl-capped oligoanilines using pseudo-high dilution technique

Monodispersed phenyl-capped trianiline and tetraaniline were successfully synthesized by the reactions of diphenylamine with acetaldehyde-based Sckiffs bases of N-phenyl-1,4-phenylenediamine and 1,4-phenylenediamine, respectively, in the presence of ammonium persulfate and hydrochloric acid, subsequent deprotonation and reduction with phenylhydrazine. The reaction mechanism probably involves the slow hydrolysis of the Sckiffs bases and subsequent oxidative coupling reactions of the formed ammonium salts with diphenylamine at pseudo-high dilution condition of the salts.

Crystallization and melting behavior of poly(p-phenylene sulfide) in blends with poly(ether sulfone)

Crystallization and melting behaviors of poly(p-phenylene sulfide) (PPS) in blends with poly(ether sulfone) (PES) prepared by melt-mixing were investigated by differential scanning calorimetry (DSC). The blends showed two glass transition temperatures corresponding to PPS- and PES-rich phases, which increased with increasing PES content, indicating that PPS and PES have some compatibility. The cold crystallization temperature of the blended PPS was a little higher than that of pure PPS. Also, the heats of crystallization and melting of the blended PPS decreased with increasing PES content, indicating that the degree of crystallinity decreased with an increase of PES content. The isothermal crystallization studies revealed that the crystallization of PPS is accelerated by blending PPS with 10 wt % PES and further addition results in the retardation. The Avrami exponent n was about 4 independent on blend composition. The activation energy of crystallization increased by blending with PES. The equilibrium melting point decreased linearly with increasing PES content.

Synthesis and properties of etherified pullulans

Abstract Propyl- and butyl-etherified pullulans (PrPL and BuPL) with various degree of substitution (DS: 1.02–2.61) were synthesized by the reactions of pullulan with 1-bromopropane and 1-bromobutane in the presence of sodium hydroxide, respectively. The structure of PrPL and BuPL was characterized by gel permeation chromatography, IR and 1 H-NMR spectroscopy. The alkylpullulans were water resistant and had good solubility in general organic solvents. Both PrPL and BuPL showed a clear glass transition temperature (Tg: 73–141 ° C ), which decreased with increasing DS. The PrPL and BuPL with DS 2.45 and 2.61 showed Tg at 78 and 73 ° C , and 5% weight loss temperature (Td) at 273 and 268 ° C , respectively, indicating that these alkylpullulans have a sufficient processing window in melt processing.

Synthesis and properties of thermoplastic propyl-etherified amylose

Amylose was etherified with 1-bromopropane in DMSO. The degree of substitution (DS) was varied by altering the feed ratio of 1-bromopropane. The structures of the products were characterized by IR and 1H-NMR spectroscopy. When the molar feed ratio of 1-bromopropane to hydroxyl groups of amylose was beyond 7.5, the hydroxyl groups were completely substituted with propyl ether groups. The etherified amylose with DS 1.9 showed a glass transition temperature (Tg), and that with DS 2.3 or 3.0 showed both Tg and melting temperature (Tm) (DS 3.0 means complete substitution). The etherification imparted melt processability and solubility in nonpolar organic solvent to amylose.

Electrochromic properties of polypyrrole composite films in solid polymer electrolyte

Abstract Polypyrrole (PPy)–poly(ether urethane) (PEU) and PPy–poly(ethylene-co-vinyl alcohol) (EVOH) composite films were prepared by the electrochemical polymerization of pyrrole on LiClO 4 -containing PEU and EVOH films coated on indium–tin oxide (ITO), respectively. The electrochromic device composed of ITO-coated glass/PPy–PEU (or PPy–EVOH) composite film/LiClO 4 -containing PEU (as a solid polymer electrolyte)/ITO-coated glass was fabricated and the electrochromic properties were characterized. As a result, the device using PPy–PEU composite film showed a larger difference of transmittance (Δ T ) at 800 nm between the doped and undoped states, and a shorter response time than the device using PPy–EVOH film. On the contrary, the latter device had a longer cycle lifetime under the repeated application of pulsed voltage (±3 V, 1 Hz). These electrochromic behaviors were discussed in connection with the properties of the used matrix polymers.