Situ Synthesis Of Polystyrene/SiO₂Hybrid Materials

Organic/inorganic hybrid materials have been a hot issue in the research fields of composite materials in these years. Sol-gel process is the most common and efficient way to prepare organic/inorganic hybrid materials, while mini-emulsion is a effective system to form core-shell structure. In this paper n-BuLi was used to initiate the living anionic polymerization of styrene, then triethoxychlorosilane was added to end the polymerization and a modified trimethoxysilane-terminated homopolystyrene (PS-silane) was obtained. Subsequently, PS/SiO2hybrid materials were prepared through the sol-gel process of PS-silane and TEOS. Meanwhile, a mixture of Span60and Tween80was used to form W/O mini-emulsions, which could provide the reaction space for PS-silane and TEOS to synthesize PS/SiO2hybrid particles with core-shell structure.Several parameters like ingredient ratio, catalysis, relative molecular mass of PS and the time of gel process, were changed to yield a series of PS/SiO2hybrid materials. The chemical structure, the glass transition temperature, thermo stability and micro topography are characterized by infrared spectroscopy (IR), gel permeation chromatograph(GPC), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and scanning electron microscope (SEM). Results revealed that the hybrid materials have chemical bonds between the organic and inorganic components. And the glass transition temperature of the hybrid materials decreased firstly and then increased as TEOS and water were added. But the glass transition temperature kept increased when the concentration of the H+increased. In the catalysis of ammonia, a structure that SiO2was spherical with PS film stretched over it tended to be got while an interpenetrating network was formed in the acid environment. In the gel process, perfect spherical SiO2particles were formed with more crystallographic components.PS/SiO2hybrid particles with core-shell structure were synthesized in the mini-emulsion. IR, SEM and TEM were used to characterize the hybrid particles. As observed, the hybrid particles were about500nm and distributed uniformly. Also, some agglomerated PS chains which were not tethered to SiO2existed.