Preparation and properties of polysilsesquioxanes - Preparation and properties of polymer hybrids from vinyltrimethoxysilane

Polymer hybrids were prepared by radical polymerization of vinyltrimethoxysilane with t-butyl peroxide (DTBP) as an initiator followed by acid-catalyzed hydrorytic polycondensation to investigate the relationship between the structure of hybrids and the properties of the films. Radical polymerization of vinyltrimethoxysilane (VTS) with various molar ratios of DTBP to VTS provided polyvinyltrimethoxysilanes with different degrees of polymerization (DP=46 similar to 74) which were hydrolyzed to prepare polyvinylpolysilsesquioxanes (PVPS) with various molecular weights (M-w = 5000 similar to 170000) and degrees of condensation of siloxane linkage (DC=7 similar to 13%). Transparent, colorless and flexible free-standing films (thickness: 0.04 similar to 0.07 mm) were prepared by casting PVPS on the polymethylpentene shale followed by heating at 80 degrees C for 10 days. Homogeneous, colorless and transparent coating films (thickness: 0.39 similar to 0.56 mu m) were prepared by dipping the several organic, metal and ceramic substrates into 20 wt% acetone-methanol solution of PVPS. Mechanical properties of the free-standing films were measured and surface hardness and adhesion to the substrates of coating films were evaluated by pencil scratch test and cross-cut tape test, respectively, according to JIS K 5400. In the same way, the radical polymerization of methacryloxypropyltrimethoxysilane (MAS) followed by hydrolytic polycondensation provided transparent and colorless free-standing films (thickness : 0.02 similar to 0.15 mm) and coating films (thickness : 1.23 similar to 2.45 mu m) of polymethacryloxypropylpolysilsesquioxane (PMPS).