Facile in situ construction of a covalent adaptable network polyester vitrimer with advanced performance in repairability, foamability and recyclability

Abstract

As the most produced thermoplastic after polyolefins, an urgent issue for polyesters is to improve their environmentally friendliness in processing, application, and recycling. However, the performance of polyesters significantly deteriorates in the above stages. This work breaks through the difficulties when applying traditional polyesters by the green in situ construction of a novel covalent adaptable network, which has an ultrafast exchange reaction rate attributed to the synergistic catalytic effect of neighboring group participation (NGP) and the tertiary amine structure. This polyester-based vitrimer shows advanced performance in repairability (fast self-healing), foamability (matching fast CO₂ diffusion) and recyclability (efficient reprocessing), due to the ultrafast exchange reaction rate in the system. The obtained vitrimer then possesses excellent self-healing behavior, as the damage was recovered within 32 min at 245 °C, possesses great foamability, as the foam prepared via green scCO₂ foaming technology has a density as low as 0.039 g cm⁻³ and has a thermal conductivity as low as 28 mW/(m K)⁻¹, and, meanwhile, possesses an advanced reprocessing ability without performance loss. Furthermore, the proposed strategy shortens the preparation time of the vitrimer to 3.5 min, providing a practical green method for the continuous process and industrial production of the polyester vitrimer via the synergistic catalytic effect of NGP and the tertiary amine structure, which is also constructive to the improved performance, environmentally friendly upcycling, and green application of the polyester vitrimer.