Ring-opening polymerization of a five-membered lactone trans-fused to a cyclohexane ring

Abstract

The ring-opening polymerization behavior of five-membered lactones fused to a cyclohexane ring (that is, the trans- and cis-hexahydro-2(3H)-benzofuranone denoted T6L and C6L, respectively) was investigated under various conditions. The potassium tert-butoxide (t BuOK)-initiated anionic polymerization of T6L yields polymers with number-average molecular weight (Mn) values of 5000. However, no polymeric products were obtained via cationic and coordination polymerization. Among the anionic initiators, a base stronger than an alkoxide initiated the polymerization of T6L. In contrast, cis-isomer C6L did not polymerize regardless of the initiator species used, which implied an increase in the ring strain of the lactone ring by the trans-fused cyclohexane. The anionic polymerization of T6L was reversible, and the thermodynamic parameters characterizing the polymerization of T6L were estimated to be ΔH p °=-18 kJ·mol -1 and ΔS p °=-65 J·K -1 mol -1 on the basis of the measurement of the equilibrium monomer concentration. © 2014 The Society of Polymer Science, Japan (SPSJ) All rights reserved.