Thermal deesterification and decarboxylation of alternating copolymers of styrene with β-substituted t-butyl α-cyanoacrylates

Alternating copolymers of styrene with β-carboalkoxy-substituted t-butyl α-cyanoacrylates undergo facile deesterification at 150–190°C, about 60°C below the deprotection temperature of poly(t-butyl methacrylate), and decarboxylation at 170–200°C. When the β-substituent is a methyl ester, the two events are clearly separated, with the deesterification occurring at a maximum rate at 165°C and decarboxylation at 193°C. Anhydride formation is negligible in this case. The copolymer with t-butyl cyanofumarate exhibits simultaneous deesterification and decarboxylation events at 180°C with concomitant minor dehydration.