Lewis Acid-Base Pair-Regulated Ring-Opening Copolymerization of Succinic Anhydride and Tetrahydrofuran†

The cationic ring-opening copolymerization (ROCOP) of succinic anhydride (SA) and tetrahydrofuran (THF) was conducted using aluminium trifluoromethanesulfonate (Al(OTf) ₃ ) via bulk polymerization to synthesize poly(butylene succinate) (PBS). The molecular weight and ester content of products were regulated by constructing Lewis acid-base pairs through the introduction of co-catalysts. Compared with the control group without co-catalysts, the resulting products exhibited significant enhancements in molecular weight. The polyester product with 99.38% ester content was achieved by incorporating gallic acid as co-catalyst. When sodium dihydrogen phosphate (NaH ₂ PO ₄ ) was employed as co-catalyst, a product with molecular weight of 4.008 kDa was obtained. The employment of Lewis base as a co-catalyst yielded products with 85.93% ester content and molecular weight of 4.570 kDa. The regulatory mechanism of Lewis acid-base pairs in this system was systematically investigated based on experimental results, demonstrating potential application prospects in industrial-scale production.