Polymers containing pendant lactone groups: synthesis and potential for sustainable materials

The transition from fossil-based plastics to sustainable and circular polymer materials requires not only renewable feedstocks but also chemically diverse structural motifs. Lactones, cyclic esters present in natural products and pharmaceuticals, occupy a privileged position in polyester synthesis. While they are classically exploited as monomers for ring-opening polymerization to produce polyesters, vinyl-functionalized lactones and lactone-derived motifs offer a broader design space when incorporated as pendant groups into synthetic polymer backbones. In particular, the five- and six-membered ring structures of γ-and δ-lactones impart properties like those of their acrylate counterparts. Inspired by their natural occurrence and developments in biorefinery technologies, polymers bearing pendant lactone groups are emerging as attractive functional materials. In this minireview, we highlight polymers bearing pendant five- and six-membered lactone groups as an emerging platform for sustainable polymer materials.