Comb graft copolymers prepared by macromonomer technique has become applicable for permanent modification of polymer surfaces. In this paper the association and adsorption behavior in solution of the well designed graft copolymer prepared from polystyrene macromonomer and various hydrophilic comonomer was studied and the mechanism of surface accumulation of hydrophilic segment was clarified by surface analysis of polystyrene containing the graft copolymers. Wetting of modified polymer surfaces and the permeability of gases through the film was also discussed.