Stereoregular polycarbonate synthesis: Alternating copolymerization of CO2 with aliphatic terminal epoxides catalyzed by multichiral cobalt(III) complexes

Abstract

AbstractCompletely stereoregular polycarbonate synthesis was achieved with the use of unsymmetric multichiral cobalt‐based complexes bearing a derived chiral BINOL and an appended 1,5,7‐triabicyclo[4.4.0] dec‐5‐ene as catalyst for the copolymerization of CO2 and aliphatic terminal epoxides at mild conditions. The (S,S,S)‐Co(III) complex 1c with sterically hindered substituent group is more stereoregular catalyst for the copolymerization of CO2 and racemic propylene oxide to afford a perfectly regioregular poly(propylene carbonate) (PPC), with >99% head‐to‐tail linkages, >99% carbonate linkages, and a Krel of 24.4 for the enchainment of (R)‐epoxide over (S)‐epoxide. The isotactic PPC exhibits an enhanced glass transition temperature of 47 °C, which is 10–12 °C higher than that of the corresponding irregular polycarbonate. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.