Department of Chemistry and Chemical Biology and Joint Center for Energy Storage Research, Baker Laboratory, Cornell University, Ithaca, NY 14853, USA.
Science. 2021 Aug 13;373(6556):783-789. doi: 10.1126/science.abh0626.
Identifying plastics capable of chemical recycling to monomer (CRM) is the foremost challenge in creating a sustainable circular plastic economy. Polyacetals are promising candidates for CRM but lack useful tensile strengths owing to the low molecular weights produced using current uncontrolled cationic ring-opening polymerization (CROP) methods. Here, we present reversible-deactivation CROP of cyclic acetals using a commercial halomethyl ether initiator and an indium(III) bromide catalyst. Using this method, we synthesize poly(1,3-dioxolane) (PDXL), which demonstrates tensile strength comparable to some commodity polyolefins. Depolymerization of PDXL using strong acid catalysts returns monomer in near-quantitative yield and even proceeds from a commodity plastic waste mixture. Our efficient polymerization method affords a tough thermoplastic that can undergo selective depolymerization to monomer.
确定能够化学回收为单体（CRM）的塑料是建立可持续循环塑料经济的首要挑战。聚缩醛是 CRM 的有前途的候选材料，但由于目前使用不受控制的阳离子开环聚合（CROP）方法生产的低分子量，其缺乏有用的拉伸强度。在这里，我们使用商业的卤代甲基醚引发剂和三溴化铟（III）催化剂，展示了环状缩醛的可逆失活 CROP。使用这种方法，我们合成了具有与一些商品聚烯烃相当的拉伸强度的聚（1,3-二氧戊环）（PDXL）。使用强酸催化剂对 PDXL 进行解聚可近乎定量地回收单体，甚至可以从商品塑料废物混合物中进行。我们的高效聚合方法提供了一种坚韧的热塑性塑料，可进行选择性解聚为单体。
