Surface grafting of polymers onto ultrafine silica: cationic polymerization initiated by benzylium perchlorate groups introduced onto ultrafine silica surface

Summary The cationic graft polymerization initiated by benzylium perchlorate groups introduced onto ultrafine silica surface was investigated. The introduction of benzylium perchlorate groups onto the surface was achieved by the reaction of silver perchlorate with surface benzyl chloride groups, which were introduced by the treatment of silica with 4-(chloromethyl)phenyltrimethoxysilane. The cationic graft polymerization of styrene and cationic ring-opening polymerization of -caprolactone were found to be initiated by the surface benzylium perchlorate groups and the corresponding polymers were grafted onto the surface. The percentage of grafting onto silica surface decreased with increasing polymerization temperature, because chain transfer reaction of growing polymer cation is accelerated with increasing polymerization temperature.