ELECTROINITIATED GRAFT-COPOLYMERIZATION

A technique has been developed for initiating a graft copolymerization electrochemically. A copoly(styrene/vinylbenzophenone) linear copolymer was prepared to serve as the electroactive starting material. The benzophenone sites on this molecule are readily activated at the cathode. Macroradical ions result from the direct transfer of electrons to benzophenone groups of the electroactive backbone polymer. In solutions in N,N-dimethylformamide with tetraethylammonium perchlorate (TEAP) as supporting electrolyte the passage of current produced a dark blue solution similar to that observed with radical anions obtained with benzophenone directly. When monomer such as acrylonitrile or methyl methacrylate was added, a graft copolymer was formed. Graft copolymers were characterized by gel permeation chromatography (GPC), infrared (IR), and solvent extraction. High grafting efficiency (i. e. , free from homopolymer) can be obtained under appropriate conditions. Suitable mechanisms are proposed, compared, and discussed.