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 (M_n = 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.