Cationic ring-opening polymerization behavior of an aliphatic seven-membered cyclic carbonate, 1,3-dioxepan-2-one

Abstract

Synthesis and cationic ring-opening polymerization of a seven-membered cyclic carbonate, 1,3-dioxepan-2-one (1), were examined. The cationic ring-opening polymerization of 1 proceeded without decarboxylation at 20°C to give the corresponding polycarbonate, differently from a six-membered cyclic carbonate (2), for which polymerization is generally accompanied by partial elimination of carbon dioxide. The observed polymerization rate of 1 in nitrobenzene was about 1.3 times faster than that in dichloromethane. The observed pseudo first-order polymerization rate constants of 1 and 2 at 20°C were determined to be 4.15 × 10−4 and 4.16 × 10−6S−1, respectively. The observed polymerization rate of 1 was 100 times larger than that of 2. The activation energies in the polymerization of 1 and 2 were estimated to be 6.27 and 8.52 kcal/mol, respectively.