Salen–cobalt catalyzed degradation of polypropylene carbonate and its application in one-pot tandem synthesis of propylene carbonate

Abstract

The polymerization and degradation behaviors of polypropylene carbonate (PPC) of different molecular weights were explored in the presence of catalyst Salen–Co(III)–Cl. The degradation of low-molecular-weight PPC (M_n = 2500 g mol⁻¹, Đ = 1.01) was studied in detail, which was a second-order reaction related to the molar concentrations of PPC and the catalyst. Catalyzed by salen–cobalt, the degradation reaction proceeded spontaneously and could be completed at room temperature and atmospheric pressure, which provided a green and economical method for chemical degradation recycling of CO₂-based polycarbonate plastics. On the basis of the degradation investigation, a method for the synthesis of cyclic propylene carbonate from propylene oxide and CO₂ at room temperature and atmospheric pressure was developed.