Facile upcycling of poly(bisphenol A carbonate) via dynamic covalently cross-linked networks

Abstract

Poly(bisphenol A carbonate, PC) is a high-value engineering plastic with outstanding mechanical properties. With its rapidly growing consumption, the reuse and upcycling of PC are becoming increasingly attractive. In this study, the rigid long-chain PC was converted into readily soluble oligomers and bisphenol A (BPA) via transesterification. A reprocessable cross-linked polymer (OCI-T) was then synthesized directly from these recycled products through dynamic urethane bond formation, and the dynamic reconstruction behavior of the resulting network was systematically analyzed and compared. With an optimized cross-linking architecture, OCI-T demonstrated tensile strength (72 MPa) and glass-transition temperature (138 °C) comparable to those of virgin PC, along with superior room-temperature creep resistance and improved solvent resistance. Due to its composition of lower molecular weight degradation products and the presence of dynamic bonds, OCI-T proved to be suitable for solution impregnation processes in the fabrication of fiber-reinforced composites. Glass-fiber-reinforced OCI-T composites exhibited flexural strength 16% higher than that of virgin PC, impact strength on par with PC, and the potential to serve as a cost-effective yet robust alternative engineering plastic. The developed upcycling approach was also successfully applied to practically waste CDs, yielding a reprocessable cross-linked polymer with enhanced mechanical performance. In summary, through a dynamic cross-linking strategy, this widely used traditional polymer, after recycling, can fulfill a new role as a repairable composite matrix with excellent processability.