A One-Step Route to CO₂ -Based Block Copolymers by Simultaneous ROCOP of CO₂ /Epoxides and RAFT Polymerization of Vinyl Monomers

The one-step synthesis of well-defined CO2 -based diblock copolymers was achieved by simultaneous ring-opening copolymerization (ROCOP) of CO2 /epoxides and RAFT polymerization of vinyl monomers using a trithiocarbonate compound bearing a carboxylic group (TTC-COOH) as the bifunctional chain transfer agent (CTA). The double chain-transfer effect allows for independent and precise control over the molecular weight of the two blocks and ensures narrow polydispersities of the resultant block copolymers (1.09-1.14). Notably, an unusual axial group exchange reaction between the aluminum porphyrin catalyst and TTC-COOH impedes the formation of homopolycarbonates. By taking advantage of the RAFT technique, it is able to meet the stringent demand for functionality control to well expand the application scopes of CO2 -based polycarbonates.