Both “condensation” and “hydrosilylation” reactions have been successfully applied for the synthesis of silicon-based interpenetrating polymer networks (IPNs) consisting of a stable Si−O and Si−C linkage. We adopted 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 as the two components for the IPN. The combined LDS/PCS curing system was studied to try to obtain homogeneously cured material, which may lead to IPN formation, by using both reactions selectively in one pot for chain-extending and cross-linking of both components, respectively. We synthesized the 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 transparent cured product. The morphology of the cured LDS/PCS (8/2) was examined 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 the LDS/PCS (8/2) cured sample were better than the calculated values from each component's value. The experimental data imply the IPN structure of the cured LDS/PCS.

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A novel germanium-containing copolymer 3a having a germanium(1V) unit and a trimethylene sulfide unit altematingly in the main chain was prepared by the combined use of a germylene, l,3-bis(trimethylsily1)-1,3-diaza-2-germa(II)-indan (1 a) and thietane (2).The resulting copolymer has a very high molecular weight (a, > lo6). The usage of a germylene, bis[bis(trimethylsilyl)aminato]germanium(II) (1 b), as a comonomer also gave an alternating copolymer 3b with high molecular weight in good yields. On the other hand, the reaction of a germylene, bis(N-trimethylsilyl-tert-buty1aminato)germanium(I1) (c), with thietane afforded a 1 : 1 adduct 4c having a I-thia-2-germacyclopentane structure without producing an alternating copolymer.

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