Electroinitiated graft copolymerization

Abstract

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 solution 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. Electrolysis of solutions of the backbone polymer in tetrahydrofurn (THF), with sodium tetraphenylboride as supporting electrolyte, produced relatively stable, persistent macroradical anions and, under appropriate conditions, the reddish‐violet macrodianions. Both types initiated graft copolymerization of acrylonitrile and methyl methacrylate. 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.

Enhancement of the high‐temperature properties of an SEBS thermoplastic elastomer by chemical modification

“…Many investigators have investigated the benzoylation of polystyrene using benzoyl chloride, aluminum chloride, and solvents such as carbon disulfide, methylene chloride, and nitrobenzene 20–28. The reaction occurs cleanly and in high yield.…”

Synthesis and characterization of perfectly alternating polycarbonate‐polydimethylsiloxane multiblock copolymers possessing controlled block lengths

“…Grubbs et al [36] conducted an extensive investigation of the thermal stability of PC-PDMS multiblock copolymers with a random distribution of blocks and attributed the first step of the degradation process to thermo-oxidative reactions involving methyl groups in the PDMS blocks and endgroups of the PC component. The second step of the degradation was believed to be primarily due to depolymerization of the PDMS component [37][38][39]. The most significant difference between the TGA thermograms shown in Fig.…”

Polyacrylamide Electrogeneration at High‐Current Densities and Different Water Content in DMF / NaNO3 Solutions

“…The increment of the water discharge when its concentration increases seems related to a progressive rise of water content in the polymeric film (the hygroscopicity of polyacrylamide is well known). This fact can be described by a physical equilibrium between water in solution and water in polyacrylamide n (H~O).~o~ + (polymer)m~ ee [polymer (H~O)~]~.~ [20] The water discharge promotes the oxygen production (inhibitor of the polymerization) O~ + AA ~ --> radical scavenging [21] The production of the inhibitor is proportional to the water content subsequently. The polymerization rate decreases when the water content rises.…”