Furfural-derived 5-alkoxy-2(5H)-furanones as cationically copolymerizable cyclic hemiacetal esters†

Abstract

We have focused on cyclic hemiacetal esters as monomers that undergo cationic ring-opening copolymerization. In this study, we investigated the cationic ring-opening copolymerization of 5-alkoxy-2(5H)-furanones (ROFOs), which are cyclic hemiacetal esters synthesized from a plant-derived compound (furfural) via photochemical reaction. ROFOs did not undergo cationic homopolymerization, while copolymerization with oxiranes successfully proceeded to yield polymers with ester and acetal moieties in the main chain. In addition, cationic terpolymerization of vinyl ether (VE), oxirane, and ROFO proceeded via highly selective crossover reactions, resulting in sequence-controlled terpolymers with VE_n–oxirane_m–ROFO-type periodic structures. The co- and terpolymers could be degraded by acid hydrolysis via the scission of the acetal moieties in the main chain. The copolymers obtained from ROFO have β-substituted acrylate structures in the main chain; hence, the polymers could be modified by the thiol–ene reaction.