Closed-Loop Recycling of Depolymerizing Poly(butylene succinate) as Chemical Monomers

As a typical biodegradable plastic, poly(butylene succinate) (PBS) is increasingly finding widespread applications. Considering the perspectives of resource utilization and ecological environmental protection, the recycling of PBS holds great significance. In this study, we introduce an alkaline hydrolysis method for the closed-loop recycling of PBS plastics. Under optimized conditions (140 °C, using deionized water as a dispersant, with 4 mmol of sodium hydroxide), 1 g of PBS (Mw = 1.8 × 105 g/mol) can be completely depolymerized into succinic acid and 1,4-butanediol within 4 h. The conversion rate approaches 100%, while the yields of succinic acid and 1,4-butanediol both exceed 90%. This method is applicable to various types of PBS plastics and demonstrates selectivity for PBS over other polyester plastics, offering a significant advantage when processing complex plastic mixtures. This method does not require transesterification reactions and expensive catalysts, paving the way for the potential closed-loop recycling of PBS plastics.