Fabrication of recyclable and biodegradable PBAT vitrimer via construction of highly dynamic cross-linked network

The emergence of biodegradable materials has not satisfactorily addressed the issue of plastic waste management, owing to their high cost and poor mechanical performance and durability that impair their potential to replace traditional plastics. In this study, a dynamic cross-linked network with robust remoldability was fabricated in PBAT. Transesterification catalysts were employed to catalyze the reaction of β-hydroxyl groups produced from the branching reaction of polyester end groups and epoxy branching agents with the abundant ester groups of PBAT to produce biodegradable PBAT vitrimers. Swelling experiments, DMA tests and stress relaxation experiments confirmed the presence of the dynamic cross-linking structure, while rheological analysis demonstrated that the highly catalyst-loaded PBAT vitrimer dynamic cross-linked network could achieve chain relaxation by exchanging bonds quickly at physical entanglement and chemical cross-linking points. Multiple recycling experiments further demonstrated that the robust dynamic cross-linked network of PBAT vitrimers possessed both strong stress relaxation ability and remoldability, thus conferring excellent recyclability to PBAT. Upon recycling 4 times, the elongation at break of the PBAT vitrimer remained at 93.46 % (with a tensile strength retention of 85.99 %), whereas the raw PBAT could only maintain an elongation at break of 28.01 % (with a tensile strength retention of 56.09 %). TGA and hydrolysis experiments revealed that PBAT vitrimers exhibited better degradation performance relative to raw PBAT. PBAT vitrimers, featuring excellent mechanical performance and durability, can be recycled several times in easily recyclable settings, thus reducing production costs, and finally biodegrade after disposal, thereby serving as a viable replacement for traditional plastics. This straightforward and practicable approach provides a solution for plastic waste management.