Color change of alternating copolymers with phenyl vinylethylene carbonate and N-phenylmaleimide in a solution and in the solid-state, depending on their structure

Abstract

Radical copolymerization, with various monomer feeds of phenyl vinylethylene carbonate (PVEC) and N-phenylmaleimide (PMI), successfully proceeded through selective vinyl and alternating polymerization to obtain copolymers having the maleimide unit in the main-chain and the five-membered cyclic carbonate group in the side-chain. The structure of these copolymers was analyzed in detail using NMR, IR, and UV-Vis methods. The UV-Vis spectra supported the tautomerization of the maleimide unit based on the solvent effect and the alternating and/or homo sequence constructed depending on the monomer feeds. Furthermore, these copolymers exhibited sensitive and reversible color changes based on acid–base switching not only in solution but also in the solid-state. In particular, the color change in the solid-state occurred immediately after exposure to the amine vapor.