Closed-loop recycling of biodegradable poly(butylene adipate-co-terephthalate) based on hydrolysis and repolymerization strategy

Poly(butylene adipate-co-terephthalate) (PBAT) is one of the most widely used biodegradable plastics. Recycling post-consumer PBAT products not only conserves primary energy but also mitigates environmental risks, particularly to marine ecosystems. This work presents a novel hydrolysis-repolymerization strategy for the chemical recycling of PBAT. In this strategy, PBAT hydrolysis occurred under hydrothermal conditions at 170 degrees C, using water as the only solvent and adipic acid, the monomer of PBAT, as an organic acid catalyst. As the hydrolysis yield of PBAT increased, the polymer was converted to oligomers or monomers, which could be directly used for repolymerization without separation steps. By introducing additional raw materials and a polymerization catalyst into the system, resynthesized PBAT could be obtained with mechanical and thermal properties approximating commercial PBAT. In addition, this strategy enabled selective hydrolysis of PBAT/polylactic acid (PLA) blends to recycle the two polyesters separately. It was also possible to prepare poly(butylene adipate-coterephthalate-co-lactide) (PBATL) copolyesters with potential seawater degradation performance by one-step hydrolysis and polymerization of PBAT/PLA blends. This work introduces a novel approach to recycling biodegradable polyesters, offering innovative insights into sustainable waste management.