Isospecific Copolymerization of Cyclohexene Oxide and Carbon Dioxide Catalyzed by Dialkylmagnesium Compounds

Herein we report the synthesis of isotactically enriched poly(cyclohexene carbonate) (PCHC) by the bulk alternating copolymerization of meso-cyclohexene oxide and carbon dioxide using dialkylmagnesium compounds as catalyst. These simple achiral catalysts showed good activity for the isoselective copolymerization, with high yield and high carbonate-linkage contents, in a controlled manner under mild conditions and atmospheric CO2 pressure. The triad sequences in the C-13 NMR spectra of these polymers were assigned using Bernoullian statistical methods in order to determine the tacticity of the copolymer. Differential scanning calorimetry analysis confirmed the formation of highly isotactic polycarbonate. Furthermore, kinetic studies and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry investigations allowed us to shed light on the reaction mechanism of the polymerization process.