Benzophenone-initiated grafting photopolymerization of acrylic acid on the surface of polyethylene from the monomer aqueous solution without its deaeration

Abstract

The photoinduced grafting polymerization of a functional monomer (acrylic acid) is performed on the surface of a polymeric material (polyethylene film) from a nondeaerated aqueous solution of the monomer with the use of a water-insoluble photoinitiator (benzophenone). According to the developed method, the photoinitiator is first deposited on the surface of the polyethylene film from solution in a volatile solvent; then, the surface of the film is covered with a layer of the nondeaerated aqueous solution of the monomer, over which a quartz plate or the second polyethylene film is placed, and the resulting sandwich is exposed to UV radiation. This method is highly efficient when the thickness of the monomer-solution layer is less than 100 μm. Owing to the small thickness of the monomer solution layer and the absence of the inflow of atmospheric oxygen, molecular oxygen that is initially contained in the monomer solution is rapidly consumed in photooxidation reactions occurring on the surface of the substrate polymer; therefore, molecular oxygen insignificantly affects the efficiency of grafting polymerization.