Takahisa Iwahara

Synthesis and properties of polycarbosilanes with the meta‐linkage bending unit by hydrosilylation polymerization

The polycarbosilanes (PCS) with meta-linkage bending unit ((SINGLE BOND)Me2Si(SINGLE BOND)m(SINGLE BOND)C6H4(SINGLE BOND)Me2Si(SINGLE BOND)CH2CH2(SINGLE BOND)) were successfully synthesized in mild conditions by hydrosilylation in the presence of [Pt{(CH2(DOUBLE BOND)CHSiMe2)2O}2]. The PCS obtained were soluble in various solvents owing to the lowering of the crystallinity. These properties are well compared with those of the PCS [(SINGLE BOND)Me2Si(SINGLE BOND)p(SINGLE BOND)C6H4(SINGLE BOND)Me2Si(SINGLE BOND)CH2CH2(SINGLE BOND)]n.

Silicon‐based materials prepared by IPN formation and their properties

Both condensation and hydrosilylation reactions have been successfully applied to the synthesis of silicon-based interpenetrating polymer networks (IPNs) consisting of a stable Si-O and/or a Si-C linkage. A ladder silsesquioxane oligomer (LDS 1, commercial name: Glass Resin GR100) and a polycarbosilane (PCS) by hydrosilylation polymerization of bifunctional Si-H and Si-vinyl monomers were used as the two components for the IPN (Table I). Si-based IPN material was prepared by melt-and-compression-molding method of the B-staged resin. Evaluating the flow-curing nature of the B-staged resin thus obtained with a KOKA-type flow tester led to suitable conditions for melt-and-compression molding. LDS/PCS materials with various shapes (3-4 mm thick) were prepared by melt-and-compression molding. The mechanical properties of the LDS/PCS materials were evaluated. The flexural modulus and Izod impact strength of LDS/PCS (8:2 w/w) were larger than those of each component, a tendency that proved to be a positive effect derived from IPN formation in the LDS/PCS combined system. In addition, the thermal, electrical, and optical properties of these silicon-based materials were studied and are reported on.