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.

No abstract

No abstract

The aim of this investigation is the development of crosslinked polycarbosilanes (PCSs) with excellence on mechanical properties. Crosslinked polycarbosilanes were obtained by using a hydrosilylation curing reaction between multi-functional vinylsilanes and hydrosilanes. The PCSs were prepared with a casting method from the monomer solution, The mechanical properties and the glass transition temperatures (T.s) of the PCSs were measured by a flexural test and Diflerential Scanning Calorimetry (DSC), 29 Si solid-state NMR spectroscopy was employed for estimating the conversion of the vinylsilanes. The effects of the following three points on the mechanical properties of the crosslinked PCSs were evaluated: (I) the molecular weight between the crosslinking points, (2) the introduction of !lexural units, and (3) the network chain density. The mechanical properties and r.s of the PCSs were found to be dependent on the structures of the monomer used. It was clear that both the high network chain density and the rigid-rod unit, [ Me 2 Sip -C6 H 4-Me2Si CH 2 CH2-], are favorable to high mechanical properties. The improvement in strength can be related to the structures of vinylsilancs and hydrosilanes used. KEY WORDS Polycarbosilane! Crosslinked Polymer/ Hydrosilylation Cure/ 29 Si Solid-State Nuclear Magnetic Resonance j Network Chain Density I Mechanical and Thermal Property! Rigid-Rod Polymer I

Novel fluorescent 3,6-diaryl-4-phenyl-2-pyridone derivatives were synthesized and their fluorescent properties were investigated. These compounds emit intense brilliant blue fluorescence only in the solid state, not in solution. An electron-donating substituent on the 6-phenyl group caused a red-shift in fluorescence maxima.