Hisao Ichijo

Thermo-responsive devices using poly(vinyl methyl ether) hydrogels

Aqueous solution of poly(vinyl methyl ether) (PVME) shows phase transition around 38°C. PVME hydrogel cross-linked by γ-ray irradiation is also a thermally responsive hydrogel and undergoes volume change at the same temperature; it swells below and shrinks above 38°C. PVME hydrogel prepared near phase transition temperature has heterogeneous and macroporous structure. The volume change of the macroporous hydrogel takes place rapidly with changing temperature. An attempt has been made to develop thermally activated chemomechamcal devices such as an artificial muscle model, an automatic separation system, an artificial finger model, and a photo-responsive device.

Fast responsive poly(N-sopropylacrylamide) hydrogels prepared by γ-ray irradiation

Abstract γ-ray irradiation of N-isopropylacrylamide (NIPAAm) monomer. solution resulted in the formation of the opaque poly (N-isopropylacrylamide) (PNIPAAm) gel having a microporous structure. The thermo-responsive properties of the microporous gel were the same as that of a homogeneous gel prepared by conventional methods. The gel swelled below and shrunk above the lower critical solution temperature (LCST) (33 °C). The rapid and reversible volume change was observed by changing temperature.

Robot hand with sensor for handling cloth

A robot hand to handle cloth is presented. In the study carried out, the authors tried to pick up a piece of cloth from a stack of cloth, to judge its thickness and to control the tension of it by the robot hand with a strain gauge sensor. The robot hand has two fingers with two degrees of freedom. One fingers tip was made from balsa wood, the other was made from balsa wood and phosphorus bronze plate with strain gauge sensor. The robot hand was attached to a robot arm and picked up a piece of cloth in cooperative motion with the robot arm. The hand was able to pick up a piece of wool cloth 0.4 mm in thickness. And it was able to pick up a piece of rayon cloth 0.2 mm in thickness in some trials by an automatic adjusting software. Sensor output was nearly in proportion to the thickness of cloth picked up. And sensor output was nearly in proportion to the tension of the cloth too.<<ETX>>

Separation of organic substances with thermoresponsive polymer hydrogel

Abstract Thermo-responsive polymer gel, poly(vinyl methyl ether) porous gel, was applied to the separation of organic substances in aqueous solution. Non-ionic surfactants were thermo-reversibly separated by the change of hydrophilic/hydrophobic balance of the gel. The separation technology may contribute to energy saving, environmental protection, etc.

Immobilization of biocatalysts with poly(vinyl alcohol) supports

Two polymer materials, poly(vinyl alcohol) (PVA) superfine fibers and photocrosslinkable PVA bearing styrylpyridinium groups, have been developed to immobilize biocatalysts. The former has a large surface consisting of relatively large-size pores and the fibers can immobilize a large amount of biocatalyst on their surface by ionic interaction. The latter entraps many kinds of biocatalysts by cyclodimerization caused by visible light irradiation. The biocatalysts on/in these supports maintain high activity and thermal stability. These materials can easily be formed into various shapes suitable for various applications. A new bioreactor system was constructed for evaluating a variety of biocatalysts and supports.

Electrorheological Properties of Liquid-Crystalline Materials

Abstract Electrorheological properties of binary mixtures of liquid-crystalline polymer and low molecular weight liquid crystal were investigated. The viscosity of the liquid-crystalline mixture increased by application of DC electric field and recovered its original viscosity after the electric field was turned off. The effect appears above a field strength of 1.0 kV/mm, and the viscosity increases with the electric field strength. For shear rate 2 s−1 the viscosity was increased by approximately 5 times when 5.0 kV/mm was applied. Above nematic-isotropic transition temperature, electrorheological effect disappeared.

Thermoresponsive Polymer Hydrogel

In recent years, materials responding external stimuli have become of major interest and have been applied to sensor or memory media.

Preparation of new support for immobilization of activated sludges

A new support was prepared by the combination of an oxygen enrichment hollow fiber membrane and fibrous support for immobilization of activated sludge microorganisms. A biofilm of activated sludges immobilized and grown on the support were shown to be highly active. It was confirmed that a wastewater treatment method using this new support was efficient for TOC and TN removal.

Oxygen transfer from silicone hollow fiber membrane to water

Silicone rubber hollow fiber was able to enrich the oxygen concentration in air by about 30%, and oxygen was transferred sufficiently from the membrane to water. When an aeration tank was filled with hollow fiber to up to 10% of its volume, the oxygen utilization rate, Rr, was about seven times as much as the value in the standard activated sludge method. It is suggested that there is some possibility of improving the efficiency of aerobic wastewater treatment by using this system.

Electrorheological properties of liquid-crystalline materials containing liquid-crystalline polymer of various molecular weights and spacer lengths

Abstract Polymers with cyanobiphenyl groups (PCBAn) in their side-chains with different spacer lengths (n=2, 6, 11) and different molecular weights (Mw), were prepared. The phase behavior of the polymers and that of liquid-crystalline mixtures (LCMn) consisting of PCBAn and low-molecular weight liquid crystal, were observed. LCM2 and LCM6 showed liquid-crystalline property of nematic phase, while LCM11 showed liquid-crystalline property of smectic phase. The electrorheological properties of LCMn were investigated. The viscosity of LCMn increased upon application of a DC electric field, and the degree of increase was characteristic to each n value. LCM6 of different Mw showed nearly the same electrorheological behavior except for the LCM6 of lowest Mw, which displayed a large increase in viscosity upon application of the electric field.