Kobunshi - Vol. 59, No. 8 (August, 2010)

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Vol. 59, No. 8, August (2010)

Precise Synthesis and Molecular Shapes of Megamolecules Called "Dendrimer-Like Star-Branched Polymers"
Akira HIRAO
Polymeric and Organic Materials Department
Graduate School of Science and Engineering
Tokyo Institute of Technology

Dendrimer-like star-branched polymers, a novel class of hyperbranched polymers since 1998, are well-defined and similar in branched architecture to dendrimers, but composed of polymer chains linked between the junctions. Accordingly, they are much higher in molecular weight and much larger in molecular size than dendrimers. They are recognized as nano-ordered globular megamolecules and have many characteristic features, such as topological hyperbranched and hierarchic generation-based structures, different branch densities, and many termini. Their block copolymers may possibly be phase-separated, followed by self-organizing, to generate new nano-size suprastructures and supramolecular assemblies. Furthermore, the formation of alternative or several separated layer structures is highly probable. Because of such molecular characteristics, they are promising functional materials with many potential nano-applications, such as nano-reactors, enzymes and catalysts carrying layered reaction systems, multi-compartment micelles, carriers of drugs and genetic materials, shape-persistent nano-scale electronic and optical devices. Polymer Preprints, Japan 2010, 59, 55.

Development and Application of High-Strength Polyester Nanofiber
Mie KAMIYAMA
Teijin Fibers Limited, Assistant to General Manager
Production & Development Function Division
(for Nanofiber Research & Development)
We obtained the worldÕs first 700 nano meter ultra-fine polyester nanofiber by continuous research and development of state-of-the-art nano technology. The new "Sea/Island" composite spinning technology has solved the problem of unstable quality associated with conventional mass-production nanofibers. "Sea/island" composite spinning achieves a high-strength polyester nanofiber based on conjugated (2 components) spinning theory. The separation process between sea-islands components is successfully achieved with a speed of 1000 times faster in alkali solution resolution of sea polymer (modified polyester) than island polymer (polyester). The resulting nano fiber has a very large surface area and excellent properties like absorption, distribution and an filtration effect, which makes it suitable for a variety of applications, including functional sportswear, inner wear, skin care products, filters, precision grinding cloth, etc. Polymer Preprints, Japan 2010, 59, 49.

Synthesis of Regioblock Polybutadiene with CoCl2-based Catalyst via Reversible Coordination of Lewis Base
Zhengguo CAI, Masahito SHINZAWA, Yuushou NAKAYAMA, and
Takeshi SHIONO
Graduate School of Engineering, Hiroshima University
Polybutadiene (PBD) is one of the most important polymers due to its wide range of properties depending upon its microstructure. We have recently reported that CoCl2- modified methylaluminoxane in the presence of phosphine (PPh3 or PCyPh2) gave multiblock PBDs composed of rubbery cis-1,4 and crystalline syn-1,2 sequences via reversible coordination of phosphine, where phosphine-free Co species (Co+) and phosphine-coordinated Co species (P-Co+) produced cis-1,4- and syn-1,2-PBD, respectively. Phosphine molecules should reversibly transfer between the propagation centers during polymerization at a longer interval than the rate of monomer insertion but a shorter interval than the chain lifetime results in multiblock PBD. The syndiotacticity of 1,2 sequence and the lengths of 1,2 and 1,4 sequences were controllable by selecting the type and the amount of phosphine used. Polymer Preprints, Japan 2009, 58, 2262.