Study On The Synthesis And Properties Of Multifunctional POSS And Its Copolymers

The compounds of polycarboxyl polyhedral octaphenyl silsesquioxane (COOHnOPS, n=7.0,6.6,5.5), were firstly synthesized by the bromination and BuLi-CO2 reaction with octaphenylsilsesquioxane (OPS). The structure of COOHnOPS was characterized by1H-NMR, FTIR and the controlled number of carboxyl was determined by the quantitative, NOE-suppressed 13C-NMR. COOHnOPS were cleaved by KF/H2O2and analyzed by LC-MS, the result indicates bromo located on one aromatic ring just one were transformed into carboxyl. Every carboxyl was mono-substitution carboxyphenyl.Different contents of COOH7.0OPS and COOH5.5OPS were introduced into DGEBA with solvent Process to obtain the POSS/DGEBA hybrid copolymers. The structure of hybrid copolymers was characterized by FT-IR. The result of SEM indicated all the POSS/DGEBA copolymers exhibited a homogeneous morphology. By FT-IR, DSC, TGA and DMA mechanism of that effects of thermal porperty about hybrid mar incorporation of POSS was studied.Then the COOH6.5OPS was further esterfied with 2-hydroxyethyl methacrylate (HEMA), and polymethacryl polyhedral octaphenylsilsesquioxane (HEMA6.5OPS) was obtained. After that the different amount of HEMA6.5OPS were used to copolymerize with methyl methacrylate to produce hybrid copolymers.The growth mechanism of PMMA chain in the copolymerization system were investigated by GPC methods. Compared to the pure PMMA, the copolymers with POSS content of only 0.94 mol% exhibited significantly improved thermal stabilities with 5% weight-loss temperature and glass transition temperature increased by 104℃and 21.5℃, respectively.