Ring-opening terpolymerisation of phthalic thioanhydride with carbon dioxide and epoxides

In seeking to expand the portfolio of accessible polymer structures from CO 2 waste, we report the ring-opening terpolymerisation (ROTERP) of phthalic thioanhydride with CO 2 and epoxides, forming statistical poly(ester-thioester-carbonates) by employing heterobimetallic catalysts. Both metal choice and ligand chemistry modulate the amount of CO 2 incorporated into the polymer microstructure. Terpolymerisation occurs when maintaining polymerisation rates of the faster parent ring-opening copolymerisation and this finding led us to develop the formation of CO 2 -derived terpolymers with butylene oxide at low CO 2 pressure under bicomponent catalysis. Tetrapolymerisation with added phthalic anhydride leads to the preferential polymerisation of phthalic anhydride before the polymerisation of sulfur derivatives with CO 2 and epoxides. Finally, we show that the presence of sulfur-containing thioester links leads to polymers with degradability benefits compared to those from all-oxygen derivatives. The ring-opening terpolymerisation of phthalic thioanhydride with CO 2 and epoxides leads to the formal incorporation of (photo)chemically labile thioester breaking points into the parent poly(ester-carbonate) backbone.