Overcoming limitations in ring-opening copolymerization: low-temperature, high-efficiency, and scalable synthesis of poly (propylene carbonate) from CO2 via Cs2CO3/triethylboron catalysis

The sustainable synthesis of poly (propylene carbonate) (PPC) from CO2 and propylene oxide (PO) was investigated using a combined computational and experimental approach under cesium carbonate/triethylboron (Cs2CO3/Et3B) catalysis. Conventional high-temperature (40–80 °C) ring-opening copolymerization (ROCOP) typically suffers from low selectivity, limited CO2 incorporation, broad dispersity (Đ), and reduced average molecular weights (Mn). In contrast, the (Cs2CO3/Et3B) catalyst system demonstrated significantly improved performance at lower temperatures, enabling efficient PPC formation. Furthermore, the incorporation of the phase-transfer catalyst tetrabutylammonium bromide (TBAB) enhanced CO2 solubility in PO, thereby increasing copolymerization efficiency. Temperature played a critical role in dictating reactivity: at 35 °C, the [(Cs2CO3/TBAB) Et3B] system outperformed (Cs2CO3/Et3B) alone, yielding higher selectivity, increased Mn, and narrower Đ. At 70 °C, however, the reaction shifted entirely toward the entropically favored backbiting cyclization, resulting in >99% propylene carbonate (PC). Overall, computational and experimental studies establish the [(Cs2CO3/TBAB) Et3B] catalyst system as a highly active and versatile platform for efficient and tunable ROCOP.