Organic-inorganic hybrid sol-gel materials .1. Preparation and characterization

Three organic-inorganic hybrid materials have been prepared by incorporating poly(styrene-co-methyl methacrylate) (poly(St-co-MMA)), poly(methyl methacrylate) (PMMA), and polystyrene (PS) structure units covalently into the SiO2 glass network via the sol-gel approach. The polymer precursors were synthesized by free-radical copolymerization of styrene and/or methyl methacrylate with 3-(trimethoxysilyl)propyl methacrylate (MSMA) to obtain the poly(St-co-MMA-co-MSMA) copolymer (molar ratio St/MMA/MSMA = 30/48/22), poly(MMA-co-MSMA) copolymer (molar ratio MMA/MSMA = 76/24), and poly(St-co-MSMA) copolymer (molar ratio St/MSMA = 69/31) with glass transition temperatures at about 67 degrees C, 68 degrees C, and 61 degrees C, respectively. The characteristics and properties of the copolymers were characterized by H-1 NMR, Fourier-transform infrared spectroscopy (FTIR), gel-permeation chromatography (GPC), elemental analysis, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The copolymers were then hydrolysed and co-condensated with tetraethyl orthosilicate (TEOS) in tetrahydrofuran at room temperature to afford monolithic poly(St-co-MMA)-SiO2, PMMA-SiO2, and PS-SiO2 hybrid sol-gel materials having SiO2 contents of 16-84 wt.-%. The thermal properties of the hybrid materials were characterized by TGA and DSC.