Thermal Degradation of Polymers and Polymer Models. V A Model for Copoly(styrene- methyl methacrylate)

Abstract

The synthesis of (±)- and meso-dimethyl 2, 3-dimethyl-2, 3-bis(2′-methyl-2′-phenylpropyl)butane-dioate from methyl 2, 4-dimethyl-4-phenylpentanoate, via a silyl enol acetal, is described. The X-ray structure of the meso isomer shows serious distortions from normal bond lengths and angles, most notably a length of 162.7(4) pm for the crowded central C-C bond. The compounds were synthesized as models for head-to-head units which might form by chain termination through dimerization of macroradicals during copolymerization of styrene and methyl methacrylate. Thermal degradation of the diphenyl -substituted diesters at 210° gave products which may have formed by plausible routes from radicals res..