Efficient Synthesis of High-Molecular-Weight Biobased Polycarbonates by Lithium Lactate

Biobased polycarbonates have attracted a wide range of interest due to sustainable resources; however, the synthesis of biobased polycarbonates with a high molecular weight remains a great challenge on account of the influence of catalysts. Herein, biobased poly(isosorbide carbonate) (PIC) with a high molecular weight of 105.0 kDa and excellent light transparency was synthesized via melt polycondensation of isosorbide and diphenyl carbonate by an efficient lithium lactate catalyst under mild conditions, including a short transesterification time of 0.5 h at a low reaction temperature of 150 °C, followed by polycondensation at 200 °C for 1 h. Furthermore, the structures of reaction intermediates and polymers were characterized, and the catalytic mechanism was elucidated by density functional theory calculations. Such a low-cost commercial catalyst would have a broad application prospect in the industrial production of PIC.