Lewis acid-base pairs catalyzed synthesis of high molecular weight poly(propylene carbonate) from propylene oxide, CO2 and trace amounts of 4,4-Oxydiphthalic anhydride

Metal-free catalytic copolymerization of carbon dioxide (CO 2 ) and propylene oxide (PO) has attracted considerable attention, yet poly(propylene carbonate) (PPC) obtained by one-pot metal-free routes often exhibits low molecular weight and limited thermal stability. Herein, we report an efficient strategy employing a Lewis acid–base pair catalyst, N,N-dimethylcyclohexylamine (DMCHA) and triethylborane (TEB), in combination with trace amounts of 4,4′-oxydiphthalic anhydride (ODPA) to synthesize high-molecular-weight PPC. ODPA markedly accelerates terpolymerization and enhances polymer thermal performance. Under optimal conditions (DMCHA/TEB/PO = 1/2/2000, ODPA = 0.1 mol%), the resulting polymer achieved a number-average molecular weight (M n ) of 104 kg mol −1 , a dispersity (Ð) of 1.53, and a catalytic productivity of 321 g polymer g −1 catalyst. Characterization by NMR, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis confirmed the superior structure and performance of the product. Moreover, this strategy was applicable to other tertiary amines and multifunctional anhydrides, demonstrating excellent versatility. The introduction of trace multifunctional anhydrides provides a promising approach for enhancing catalyst activity and developing high-performance CO 2 -based polycarbonates.