Synthesis of biodegradable polycarbonate by alternating copolymerization of carbon dioxide and propylene oxide using a cobalt/Schiff base catalyst

Abstract

A series of cobalt/Schiff base complexes, ( R, R)-SalenCo IIIX [Salen = N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-di-phenylethylenediimine; X = OOCCF 3 ( 1), OOCCCl 3 ( 2), and OOCCH 3 ( 3)], were investigated for the alternating copolymerization of carbon dioxide with racemic propylene oxide in the presence of [PPN]Cl ([PPN] = bis(triphenylphosphine)iminium). The effect of the axial group X of the complexes and the reaction conditions on the yield, the selectivity for poly(propylene carbonate) over propylene carbonate, and the polymer molecular weight for this transformation were investigated. A high molecular weight of 72.5 kg mol −1 (Mn/Mw = 1.27, yield 76%) for the copolymer was achieved.