Surface graft polymerization of styrene onto nano-sized silica with a one-pot method

A facile method for free radical graft polymerization of styrene onto the surface of nano-sized silica was developed by using a one-pot method. The initiator (2,2′-azobisisobutyronitrile, AIBN), the coupling agent (vinyl triethoxylsilane, VTEOS), styrene and the nano-sized silica were mixed and reacted in toluene medium. The two reactions, the copolymerization of VTEOS and styrene and the coupling reaction of the ethoxyl groups in the side chains of the copolymer and the silanol groups on the surface of the nano-sized silica, were occurred synchronously in the preparing procedure. The effects of the amount of AIBN and VTEOS, the polymerizing temperature and the polymerizing time on the conversion of styrene (C), the percentage of grafting (PC), the grafting efficiency (GE) and the average relative molecular masses (M_n and M_w) of the grafted polystryrene (PS_g) and the non-grafted polystyrene (PS_n) were discussed. IR and XPS showed that the surface of the nano-sized silica had been covered partially by PS and TEM showed that the dispersibility of PS grafted nano-sized silica in organic solvent was improved.