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Vol. 61, No. 6, June (2012)

Nanomatrix Structure and Properties of Natural Rubber
Seiichi KAWAHARA
Nagaoka University of Technology

Nanomatrix structure, consisting of dispersoid of a major component and a matrix of a minor component, was formed in natural rubber, after removal of all proteins from the rubber. It was found to be a unique nano-phase separated structure by both field-emission scanning electron microscopy equipped with focused ion beam (FIB-SEM) and transmission electron micro-tomography (TEMT). Dramatic increases in mechanical properties and proton-conductivity were associated with the formation of the nanomatrix structure. Based on the results, the nanomatrix of non-rubber components such as proteins and phospholipids was found to be inherently formed in natural rubber, in which natural rubber particles of about 0.5 mm in average diameter were dispersed. It was proven that the nanomatrix structure played an important role in the outstanding mechanical properties of natural rubber.
Polymer Preprints, Japan 2011, 60, 2164.

Swollen Structure of Block Copolymers in Supercritical Fluid
Hideaki YOKOYAMA
Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo
Block copolymers (bcps) have been extensively studied and a variety of unique morphologies have been found. In general, available morphologies are directly linked to block architectures through a volume fraction of consisting blocks, f; therefore, for a given bcp, order-to-order transitions (OOT) are rarely observed. In order to obtain different morphologies, synthesis of another bcp is necessary. Instead, we employed supercritical fluids (SCF) to swell bcps selectively to change their effective f and observed multiple OOTs by controlling pressure. Not only multiple classical morphologies are found for a given bcp, but also separated bilayer morphologies typically found in surfactant and lipid systems. Those swollen morphologies in SCF are taken out to room atmosphere as unique nano-cellular and porous structures by removing SCF without disturbing the morphologies.
Polymer Preprints, Japan 2011, 60, 530.
Polymer Preprints, Japan 2011, 60, 690.
Polymer Preprints, Japan 2011, 60, 3022.
Polymer Preprints, Japan 2011, 60, 3661.

Development of Gelators and their Applications
Kenji HANABUSA
Graduate School of Science and Technology, Shinshu University
We have developed new gelators of amino acid derivatives, cyclo (dipeptide)s, two-component type, trans-(1R,2R)-diaminocyclohexane derivatives, and polymer type. They can gel a wide variety of solvents to form physical gels. Gelators are characterized by good solubility upon heating and inducement of smooth gelation of fluids at a low concentration. The driving forces for gelation phenomena are non-covalent bonds such as hydrogen bonding, electrostatic interaction, van der Waals interaction, and p-p interaction. When the gelation happens, the gelator molecules self-assemble into macromolecule-like aggregates via non-covalent intermolecular interactions. We successfully observed the fibrous self-aggregation by TEM, SEM, and fluorescence microscope. Gelators have special attention not only because of academic interest in supramolecular chemistry but most importantly because their value in practical applications. We showed that they are potentially useful as cosmetics, gel electrolytes, and ionic liquids-gels.
Polymer Preprints, Japan 2011, 60, 2173..

Improvement of the Application Force of Metal Nanoparticles by Using Polymers
Tetsu YONEZAWA
Division of Materials Science and Engineering, Faculty of Engineering, Hokkaido University
Our studies focus on the applications of metal nanoparticles reinforced by using polymers. Gelatin, one of the cost effective biopolymers, was used as the protective polymer of metallic copper nano and fine particles. The surface of copper particles can be readily oxidized in air, but gelatin coating effectively prevents surface oxidation even in powder form under ambient conditions. These particles can be re-dispersed to prepare electro-conductive pastes. Another application is optical resins, such as fluorescent resins and high index resins. By direct introduction of metal nanoparticles into monomer liquids, we have successfully obtained metal nanoparticle-incorporated transparent resins which can emit NIR lights.
Polymer Preprints, Japan 2011, 60, 3913.
Polymer Preprints, Japan 2011, 60, 2510.
Angew. Chem. Int. Ed., 2011, 50, 703.

Widely Tunable Laser Action from a Colloidal Crystal Gel Film with an Ionic Liquid
Seiichi FURUMI
National Institute for Materials Science (NIMS) and PRESTO, Japan Science and Technology Agency (JST)
Colloidal crystals (CCs)-3D ordered arrays of monodispersed colloidal microparticles-have garnered a great deal of attention as a high-throughput fabrication technique of photonic crystals. In this report, we describe a new type of widely tunable laser action based on the photonic band-gap (PBG) effect of a stable polymer CC-gel (CC-G) film. A permanently stable CC-G film could be prepared by using a non-volatile ionic liquid (IL). Optical excitation of a CC-G film with a light-emitting IL solution gave rise to a single and narrow laser emission peak by the PBG effect. In order to develop the further potential of the CC-G films, we successfully demonstrated the widely tunable laser action from the CC-G films stabilized with IL by applying mechanical stress.
Polymer Preprints, Japan 2011, 60, 2176.
Adv. Mater., 2011, 23, 3815.
NPG Asia Mater., 2011, doi: 10.1038/
asiamat.2011.170.

The Roles of Water Molecules in the Biointerface and Application of Medical Polymers
Masaru TANAKA1, Tomohiro HAYASHI2, and Shigeaki MORITA3
1Graduate School of Science and Engineering, Yamagata University
2Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology
33EcoTopia Science Institute, Nagoya University
A number of biomaterials have been proposed, including hydrophilic, phase-separated, and zwitterionic polymers. It has not been clearly elucidated which mechanisms are responsible for biocompatibility on a molecular level, although many theoretical and experimental efforts have been devoted to understand this mechanism. Water interactions have been recognized as a fundamental part of the biological response to contact with biomaterials. We have proposed the "Intermediate water" concept; the water exhibited clearly defined peaks for cold crystallization in the DSC chart and a strong peak at 3400 cm-1 in a time-resolved IR spectrum. We found that the localized hydration structure consisting of three hydrated water in poly(2-methoxyethyl acrylate) (PMEA). We are involved in organizing the 9th World Biomaterials Congress (June 1-5, 2012), to give an overview of the recent progress in the quantitative description of mechanisms of biocompatibility driven by novel approaches.
Polymer Preprints, Japan 2011, 60, 2170..
J. Biomat. Sci. Polym. Ed, Special Issue of Prof. T. Tsuruta, 2010, 21, 1827.