Amphiphilic graft copolymers of acrylic acid with uniform polystyrene grafts were prepared by copolymerization of acrylic acid with polystyrene macromer using AIBN as initiator and dimethylformide as solvent.Effects of various factors

including copolymerization temperature

time

total monomer concentration

molecular weight of the macromer and charging ratio of the macromer to monomer on grafting efficiency and molecular weight of the copolymers were studied and optimum conditions were obtained.The crude products were purfied by extractions with water and toluene successively.The purified graft copolymers exhibited good emulsifying properties and high water absorbency.Their dilute solution behaved as polyelectrolyte

Their intermolecular complex membrane with poly(ethyl acrylate)containing uniform polyoxyethylene grafts behaved like a chemical valve

since its permeability can be controlled reversibly via change of pH value.