不饱和聚酯树脂水解回收制备可循环利用的水溶性薄膜

Chemcycling of unsaturated polyester resins into reversibly recyclable water-soluble films

废弃塑料的回收利用引起了全球的广泛关注,其中热固性塑料由于树脂稳定致密的三维网络结构,回收难度极大.现有的化学回收方法存在降解条件苛刻,反应选择性低,以及未能兼顾再生产品的可回收性等不足.基于此,本文报道了一种简单温和的不饱和聚酯树脂(UPR)降解及产物高值循环利用的方法.采用二乙烯三胺和氢氧化钠二元碱体系,通过选择性地完全断裂UPR结构中的酯键,得到苯乙烯–马来酸共聚物钠盐(SMA-Na).并进一步以之为原料制备得到具有较好耐溶剂性和力学性能的水溶性薄膜.利用SMA对pH的敏感性,通过简单的水溶解–酸化提取–再成膜过程即可实现薄膜的循环再生.该工作为热固性树脂的温和高效回收与循环利用提供了新的思路.

The recycling and reutilization of waste plastics have garnered global attention,with thermosetting plastics posing a significant challenge due to their stable,dense three-dimensional network structure.Current chemcycling methods exhibit drawbacks such as harsh degradation conditions,low reaction selectivity,and neglecting the recyclability of regenerated product.This study presents a facile and mild approach to the degradation of unsaturated polyester resin(UPR)and recycling of high-value products.By selectively and completely disrupting the ester bond in UPR via a binary alkali system consisting of diethylenetriamine and sodium hydroxide,the sodium salt of styrene–maleic acid copolymer(SMA-Na)is obtained.This molecule can be used to fabricate water-soluble films that exhibit favorable solvent resistance and mechanical properties.Importantly,the pH-sensitive SMA facilitates the recycling of films through a simple process involving dissolution,acid extraction,and film reconstruction.This work provides a novel strategy for the gentle and efficient recycling and reutilization of thermosetting resins.