Hot Topics

Vol. 61, No. 7, July (2012)

Chain-Shuttling Copolymerization of Styrene and 1,3-Conjugated Dienes by Rare-Earth Catalysts
Zhaomin HOU
RIKEN Advanced Science Institute, Organometallic Chemistry Laboratory

We found that the copolymerization of styrene and 1,3-conjugated dienes could be achieved regio-, and stereospecifically on each monomer by use of two different rare-earth catalysts with a chain-shuttling agent. The copolymerization of styrene and isoprene by catalysts Sc1 (which is syndiospecific for styrene) and Sc2 (which is cis-1,4-specific for isoprene) with a chain-shuttling agent iBu3Al results in block copolymers of syndiotactic polystyrene (sPS selectivity > 99%) and cis-1,4-polyisoprene (cis-1,4-PIP selectivity > 97%), respectively. Replacement of Sc2 with Sc3 (which is highly 3,4-selective for isoprene polymerization) in this reaction produces selectively copolymers having sPS and 3,4-PIP blocks. Similarly, the terpolymerization of styrene, isoprene, and butadiene by Sc1 and Sc2 affords copolymers containing sPS, cis-1,4-PIP and cis-1,4-PBD blocks.
Angew. Chem. Int. Ed. 2011, 50, 12012.
Polymer Preprints, Japan 2011, 60, 2205.

Intelligent Material Design System based on Weak Conditioned Linear Programming
Teiichi INADA
Hitachi Chemical Co., Ltd., Tsukuba Research Laboratory
In recent years, multi-layered semiconductor package was one of the most important technologies to enhance its performance. To increase the bonds between each layer of the multi-chip package, novel low-modulus die-bonding films were developed. Properties of the films are widely changing with the ratio of epoxy resin and acrylic polymer contents. To satisfy the target properties, the influence of various parameters on material properties was examined. However, it is not easy for researchers to find which formulation satisfies the targets. To solve the problem, we propose to use the weak conditioned combinatorial linear programming method (WCCLP). By defining a solution area as a function of the combination index, the optimum formulations are acquired. This optimization can be done by a newly developed user-friendly software. The software is applicable not only to semiconductor related materials but also to any such formulation as paint, medicine and food.
Kobunshi 2010, 59, 482.
Network-polymer 2010, 2, 36.

Industrial Production Technology for High Molecular Weight Polyglycolic Acid
Hiroyuki SATO
PGA Research Laboratories, Kureha Corporation
We have established the world's first industrial scale production technology of high molecular weight polyglycolic acid (PGA). The technology employs the ring-opening polymerization process of glycolide (GL). However, traditional GL synthesis by bulk depolymerization of glycolic acid oligomer has proven industrially limited due to both poor yields and low purity from undesirable side reactions. Our innovation, which utilizes an innovated solvent for GL synthesis, resolves past yield and purity deficiencies allowing a scalable production method. Furthermore, in the production of high molecular weight PGA, the sequential melt-solid polymerization method of very high purity GL was innovated. This method was suitable for the production of well defined polymer. Besides well known PGA as biodegradable polymer uses for sutures and medical devices, several new value-added industrial applications for it have been identified which exploit the unique gas barrier, mechanical strength and degradation property.
Polymer Preprints, Japan 2012, 61, 34.
Kobunshi Ronbunshu, 2012, 69, 60.