Acid-base pair-mediated copolymerization of acid-sensitive epoxides and cyclic anhydride for synthesizing recyclable thermoplastics

Developing low-cost, high-performance, and chemically recyclable alternatives to bulk polyolefin commodities is critical. Aromatic polyesters synthesized via ring-opening copolymerization (ROCOP) of phthalic anhydride (PA) and olefin-derived epoxides are promising candidates. However, achieving high molecular weight (MW) and chemical recyclability to monomers remain key challenges, especially for epoxides with high isomerization tendency including styrene oxide, 2-vinyloxirane, and isobutylene oxide. Here, we report an organic acid-base pair-mediated strategy for the ROCOP of PA and these bulk-olefin-derived epoxides to produce high-MW (Mn = 105.1–163.3 kDa) polyesters. This strategy effectively suppressed acidic impurities-triggered, PA-mediated self-catalytic isomerization of these acid-sensitive epoxides. The produced high-MW polyesters showed superior mechanical and processing properties comparable to commodity polystyrene as well as high tensile strength (53.1–58.9 MPa) and Young’s modulus (2.16–3.02 GPa). Furthermore, these materials can be chemically recycled into PA and aldehyde monomers under mild conditions, enabling the end-of-life recycling options for ROCOP-derived polyesters. Polyesters from cyclic anhydrides and epoxides provide a recyclable alterative to polyolefins. Here, the authors report high molecular polyesters from phthalic anhydride and acid sensitive epoxies, such as styrene oxide, from which only low molecular weights were previously achieved.