Copolymerization of styrene oxide with CO2 via modular optimization of bifunctional organoborane catalysts

• Organoborane catalysts are designed for copolymerization of CO 2 and styrene oxide with adjustable carbonate linkage. The ring-opening copolymerization (ROCOP) of CO 2 and epoxides presents significant challenges, primarily due to the tendency to form cyclic carbonates, especially when the epoxide contains electron-withdrawing groups, such as styrene oxide (SO). Building upon our previous research on organoborane and cationic components, we designed a series of novel tetranuclear, trinuclear, and dinuclear bifunctional organoborane catalysts. These catalysts facilitated SO/CO 2 copolymerization with remarkable polymer selectivity exceeding 99 % under mild conditions. 31 P NMR spectroscopy revealed that the discrepancies in catalytic performance between trinuclear and dinuclear organoborane catalysts stem from variations in their overall Lewis acidity. These insights into the optimization of organoborane catalysts are expected to drive the development of more advanced catalysts in the future.