Post-polymerization functionalization of aliphatic polycarbonates using click chemistry

Abstract

Presently there is much interest in the synthesis of degradable, more sustainable polymers from resources that minimize the use of petroleum-based feedstocks. A process receiving much attention related to this challenge is the production of polycarbonates from CO₂ and epoxides or cyclic carbonates. These polymeric materials generally lack thermal and mechanical properties as well as economic feasibility to compete with the widely used polyolefins and BPA-derived polycarbonates; nevertheless, because of their degradability and biocompatibility, these CO₂-derived polymers can play valuable roles in niche applications. This implementation would be greatly enhanced by the functionalization of these polymers. A wide variety of aliphatic polycarbonates are readily synthesized via the copolymerization of epoxides and carbon dioxide. Nevertheless, these polymeric materials have limited utility, in part because of their lack of functionalities. These shortcomings can be modified by way of post-polymerization processes. Prominent among these modifications is click chemistry. Relevant pathways for these materials are thiol–ene and alkyne–azide processes. Herein, we will discuss the functionalization of polymers produced from the copolymerization of CO₂ and epoxides and the ring-opening polymerization of six-membered cyclic carbonates. We will also highlight several of the unique applications these novel materials are used for, particularly in biomedical science.