Ring-Opening Co- and Terpolymerization of Epoxides, Cyclic Anhydrides, and <scp>l</scp>-Lactide Using Constrained Aluminum Inden Complexes
Nattiya Laiwattanapaisarn, Arnut Virachotikul, Phongnarin Chumsaeng, Tiphanan Jaenjai, Khamphee Phomphrai
Abstract
Seven constrained aluminum inden complexes having different substituents and diamine backbones were developed for the ring-opening copolymerization (ROCOP) of epoxides and bulky cyclic anhydrides giving alternating polyesters with Tg ranging from 49 to 226 °C. Among several catalyst/cocatalyst screenings, the aluminum inden complex having a rigid phenylene backbone coupled with 4-dimethylaminopyridine showed the best performance giving linear polyesters. In the case of cyclohexene oxide (CHO) and succinic anhydride (SA), the linear poly(CHO-alt-SA) could be transformed to cyclic polymer when the polymerization was left under prolonged reaction time to induce intramolecular transesterification. The kinetic studies of the ROCOP revealed a zeroth-order dependence on cyclic anhydride and a first-order dependence on epoxide and the catalyst. The catalysts can be extended efficiently to the one-pot CHO/PA/l-lactide terpolymerization giving uncommon tapered copolymers of poly(CHO-alt-PA) and PLA via switchable polymerization.