CO2-Based Block Copolymers: Present and Future Designs

The utilization of carbon dioxide (CO2) as a monomer for copolymerization with three-membered cyclic ethers, also known as oxiranes or epoxides, has received much renewed interest due to the need for degradable polymeric materials derived from renewable resources. Since the early discovery of the catalytic coupling of CO2 and oxiranes to afford polycarbonates, the area has progressed significantly over the 50 succeeding years. Herein, we describe the currently well-established catalyzed copolymerization process of oxiranes and carbon dioxide utilizing homogeneous metal catalysts. Pertinent to the commercial success of this process is the presence of rapid and reversible chain-transfer re-actions that occur in the presence of protic impurities or additives leading to the formation of macropolyols. The focus of this review is to summarize the various synthetic strategies for the production of designer block copolymers for various applications in material science and biomedicine.