Functionalization of inorganic colloidal particles by polymer modification

The polymer modifications of inorganic colloidal particles, mainly silica, and the stabilization and functionalization were described. The polymer grafting procedures on colloidal silica via covalent bond bindings in order to stabilize and functionalize were presented along with the modification of inorganic particle powder. In the modifications, the reaction of the surface hydroxy groups with polymeric trialkoxysilane was effective for grafting the polymer in terms of controlling the attachment and of successive introduction of functional groups. Especially, the grafting of poly(maleic anhydride-co-styrene) (P(MA-ST)) onto colloidal silica by the reaction with P(MA-ST)-trimethoxysilane gave stable and dispersible composite particles (P(MA-ST)SiO2) in organic solvent. The introduction of secondary polymer to P(MA-ST)/ Sio(2) successfully controlled the dispersion in organic solvent and C-potential in aqueous or highly polar solvents. The modification of colloidal titania with Ru(II)-(2,2'-bipyridyl) complex-tethered polymer gave a photo-active catalyst that exhibited photoinduced electron transfer to a donor by visible light irradiation. Moreover, colloidal crystallization was observed in the suspension of monodisperse, polymer-modified silica in organic solvent, which was a good polar solvent for grafted polymer. The colloidal crystallization of the modified silica took place through close-packing under the electrostatic repulsion among the particles, as well as the crystallization of unmodified silica in aqueous solution.