PHOTOINITIATED BLOCK COPOLYMER FORMATION USING DITHIOCARBAMATE FREE-RADICAL CHEMISTRY

Photoinitiated block copolymer formation from macromolecules terminated with dithiocarbamate end groups was studied. In most experiments results consistent with those reported by Otsu et al. were observed. A previously unreported side reaction, leading to decomposition of the dithiocarbamate end groups, was observed. The extent of this reaction appeared to depend on the stability of the incipient macroradical formed during photolysis. Statistical mixtures of homopolymers and block copolymers were formed during the addition of methyl methacrylate to poly(styrene) and styrene to poly(methyl methacrylate). The dithiocarbamate radical did not readily initiate the polymerization of ethyl acrylate or butyl acrylate, thus relatively clean block copolymers formed when these monomers were added to polystyrene. © 1990, American Chemical Society. All rights reserved.