Switchable catalytic processes involving the copolymerization of epoxides and carbon dioxide for the preparation of block polymers

This minireview's primary focus is to review recent studies from my research program on the development of one-pot, two-step processes for the synthesis of di- and tri-block polymers. In all of these prepared polymeric materials at least one component is a polycarbonate derived from the copolymerization of CO2 and epoxides. Synthetic methodology for the preparation of polycarbonate diols of well-defined molecular weights with narrow polydispersities are presented using (salen) CoX/onium salt catalyst systems. These polyols were subsequently utilized in the synthesis of di-and tri- block polylactide/polycarbonate or polyphosphoester/polycarbonate polymers employing organocatalysts. In addition, the introduction of these polyols to a second epoxide/CO2 copolymerization process provided block polycarbonate materials. Of particular interest, the first or second epoxide monomer incorporated into the copolymer can possess vinyl groups for postpolymerization modification by thiol-ene chemistry. These degradable polymeric materials have significant potential for use in biomedical applications.