SILICON-BASED INTERPENETRATING POLYMER NETWORKS (IPNS) - SYNTHESIS AND PROPERTIES

Both ''condensation'' and ''hydrosilylation'' reactions have been succ essfully applied for the synthesis of silicon-based interpenetrating p olymer networks (IPNs) consisting of a stable Si-O and Si-C linkage. W e adopted a ladder silsesquioxane oligomer (LDS 1; commercial name, Gl ass Resin GR100) and a polycarbosilane (PCS) by hydrosilylation polyme rization of bifunctional Si-H and Si-vinyl monomers as the two compone nts for the IPN. The combined LDS/PCS curing system was studied to try to obtain homogeneously cured material, which may lead to IPN formati on, by using both reactions selectively in one pot for chain-extending and cross-linking of both components, respectively. We synthesized th e cured LDS/PCS; LDS/PCS = 8/2, 5/5, and 2/8 [wt/wt]. Tuning the rates of the two reactions to each other was important for obtaining a tran sparent cured product. The morphology of the cured LDS/PCS (8/2) was e xamined by TEM and AFM. TEM analysis showed a good miscibility with an nm level of LDS/PCS (8/2). The thermal and mechanical properties of t he LDS/PCS (8/2)cured sample were better than the calculated values fr om each component's value. The experimental data imply the IPN structu re of the cured LDS/PCS.