EFFECT OF INITIATING GROUPS INTRODUCED ONTO ULTRAFINE SILICA ON THE MOLECULAR-WEIGHT POLYSTYRENE GRAFTED ONTO THE SURFACE

The effect of initiating groups introduced onto silica surface on the molecular weight of grafted polystyrene chain was investigated. By the treatment of polystyrene-grafted silica with aqueous solution of alkali, surface grafted polystyrene was isolated from the surface. The molecular weight of polystyrene grafted onto the silica obtained from the radical graft polymerization initiated by peroxyester groups introduced onto the surface was found to be much larger than that from the cationic polymerization initiated by acylium perchlorate groups. The number of grafted polystyrene in the radical polymerization, however, was much less than that in the cationic polymerization. Furthermore, the effect of molecular weight of grafted polystyrene on the dispersibility of silica in tetrahydrofuran was examined.