Radical grafting polymerization of vinylformamide with functionalized silica particles

摘要

Two different radical polymerization techniques have been applied to covalently graft vinyl formamide (VFA) onto silica particles. Grafting by the polymerization of VFA using an immobilized azo initiator on silica has been found less effective, because monomer conversion is limited in non-aqueous solvents and grafting yields are low in water. Radical copolymerization of VFA with vinyltriethoxysilane (VTS)-functionalized silica particles is suitable to produce poly(vinylformamide) (PVFA) silica hybrid particles in respectable yield. The VFA/VTS-co-grafted silica particles can be acidically hydrolyzed into poly(vinylamine)-grafted silica particles. Molecular structures of the surface groups and grafted polymer chains have been confirmed by means of solid state C-13{H-1} cross-polarization magic-angle spinning (CP MAS) NMR spectroscopy. Zeta potential measurements show the altering of the former silica particles surface charges arising from the introduction of basic groups on the surface. [References: 50]