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Vol. 61, No. 4, April (2012)

High-Functionability of Biobased and Biodegradable Porous Fibers
Tadahisa IWATA
Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo

Polyhydroxyalkanoate (PHA) synthesized by a wide variety of bacteria has attracted much attention as biobased and biodegradable polyester. We succeeded to obtain high tensile strength fibers of PHA by a new drawing method with small crystal nuclei. X-ray micro-tomography with synchrotron radiation and SEM observation revealed the presence of numerous fine pores in PHA fibers. In an attempt to develop a slow-release system for drugs as biodegradation of fibers, we impregnated drugs such as an antibiotic (vancomycin) into porous PHA fibers. Antibiotic was successfully released at long time during degrading PHA porous fibers from surface by an extracellular PHA depolymerase and the activity of released antibiotic was confirmed by growth inhibition test. These high-functional fibers can be utilized as surgical suture, filter, nonwoven fabric, insect screen, agricultural net, etc.
Polymer Preprints, Japan 2011, 60, 1.

pH-Responsive Aqueous Foams Stabilized by Hairy Latex Particles
Syuji FUJII and Yoshinobu NAKAMURA
Department of Applied Chemistry, Osaka Institute of Technology
Colloidal particles with a suitable wettability to air/water are strongly adsorbed to air-water interface and can work as a foam stabilizer. Wettability is one of crucial parameters, which determine foam stability: relatively hydrophobic particles can stabilize foams and highly hydrophilic particles cannot stabilize foams and result in aqueous dispersion of particles. We utilized polystyrene (PS) particles carrying poly[2-(diethylamino)ethyl methacrylate] (PDEA) hair (PDEA-PS particles), which can change their wettability by pH stimulus, as a foam stabilizer. Above pH 8.0, where particles have non-protonated PDEA hair, which is relatively hydrophobic, stable particle-stabilized foams were formed. Below pH 5.1, where the particles have cationic water-soluble PDEA hairs with hydrophilic character, no foam was formed. Rapid defoamation can be induced by lowering the solution pH..
Polymer Preprints, Japan 2011, 60, 1406.

A New Class of Living Radical Polymerization with Organic Amines as Catalysts
Atsushi GOTO
Institute for Chemical Research, Kyoto University
A new class of living radical polymerization, reversible complexation mediated polymerization (RCMP), was developed. It uses organic amines and their salts as catalysts. It is based on reversible complexation as a new reversible activation mechanism. RCMP is applicable to a wide range of monomers including styrenics, methacrylates, and acrylates, and can also yield relatively high molecular weight polymers, up to several tens thousand molecular weights, which would be useful for macromolecular design. The catalysts are commercially available inexpensive compounds, which may be attractive for possible applications.
Polymer Preprints, Japan 2011, 60, 102.
Kobunshi Ronbunshu, 2011, 68, 223.

Hybrid Particles Decorated with Polymer Brush
Kohji OHNO
Institute for Chemical Research, Kyoto University
Various inorganic particles were surface-decorated with brushes of well-defined polymer chains prepared by surface grafting using some living polymerization systems of nitroxide-mediated, atom transfer radical, and reversible addition-fragmentation chain transfer polymerizations. Some studies were performed by making full use of high dispersibility and uniformity of thus prepared hybrid particles. The hybrids formed ordered structures of colloidal crystals and liquid-crystals depending on their structural features of graft chain length and core size and shape. The fabrication of biomedical materials using the hybrid particles is also one of the targets: some hybrid particles exhibited an excellently prolonged circulation lifetime in the blood and preferentially accumulated in tumor tissue due to the so-called enhanced permeability and retention effect. The tumor-targeted deliveries were visualized by optical and magnetic resonance imaging systems.
Polymer Preprints, Japan 2011, 60, 108.

Transfer of Stir-Induced Optical Activity Occurred from Ionic Oligomer Solution onto a Congo Red Dye
Kunihiko OKANO
Department of Pure and Applied Chemistry, Tokyo University of Science
The induction of chirality on supramolecular particles by macroscopic flows has been previously reported. Depending on the shape of the flask, an メenantiomorphicモ bias of a メchiralモ gradient of shear rates may be created and this メchiralityモ can be transferred to soft-matter particles (J-aggregates of amphiphilic porphyrins). The question thus arises as to whether such chiral induction, from the macroscopic to the supramolecular level, can mediate in the induction of chirality to a reacting system. A first step towards this controversial objective should be the chiral induction upon molecules interacting with a supramolecular structure, which becomes chiral by the effect of flows. Herein, in aqueous solutions of a cationic oligomer, chiral regions can be obtained reversibly by stirring flows. The chiral induction upon an achiral molecule (Congo Red dye) was demonstrated by Mueller matrix spectroscopy analysis of the optical polarization properties.
Polymer Preprints, Japan 2011, 60, 117.

Control of Interface Structure and Properties Using Reversibly Cross-linkable Polymers
Eriko SATO
Department of Applied Chemistry and Bioengineering, Graduate School of Engineering, Osaka City University
Wettability is one of the most important interface properties and affected by both surface free energy and surface topography of the materials. A new concept of controlling wettability was investigated using reversibly cross-linkable polymer and their volume changes. Polymers having a coumarin moiety in the side-chain are cross-linked and de-cross-linked by photochemical dimerization and reverse dimerization of the coumarin moiety, respectively. Volume shrinkage was accompanied by cross-linking when intermolecular dimerization occurs. Photo-patterning of the thin films of shrinkable polymers resulted in an indented patterned surface having different surface free energies. The indented patterned surface resulted in larger increase in the contact angle (CA) of water than the flat and smooth surface after cross-linking due to the synergy effect of the changes in surface topography and free energy.
Polymer Preprints, Japan 2011, 60, 105.