APCs (aliphatic polycarbonates) are one of the most important types of biodegradable polymers and widely used in the fields of solid electrolyte, biological medicine and biodegradable plastics. Zinc-based catalysts have the advantages of being low cost, being non-toxic, having high activity, and having excellent environmental and biological compatibility. Zinc (II) acetylacetonate (Zn(Acac)2) was first reported as a highly effective catalyst for the melt transesterification of biphenyl carbonate with 1,4-butanediol to synthesize poly(1,4-butylene carbonate)(PBC). It was found that the weight-average molecular weight of PBC derived from Zn(Acac)2 could achieve 143,500 g/mol with a yield of 85.6% under suitable reaction conditions. The Lewis acidity and steric hindrance of Zn2+ could obviously affect the catalytic performance of Zn-based catalysts for this reaction. The main reasons for the Zn(Acac)2 catalyst displaying a higher yield and Mw than other zinc-based catalysts should be ascribed to the presence of the interaction between acetylacetone ligand and Zn2+, which can provide this melt transesterification reaction with the appropriate Lewis acidity as well as the steric hindrance.
Keywords: Lewis acidity; Zinc (II) acetylacetonate; aliphatic polycarbonate; biphenyl carbonate; melt transesterification.