Shi Changxia, Diment Wilfred T, Chen Eugene Y-X
Department of Chemistry, Colorado State University, Fort Collins, Colorado, 80523-1872, United States.
Angew Chem Int Ed Engl. 2024 Aug 19;63(34):e202405083. doi: 10.1002/anie.202405083. Epub 2024 Jul 23.
Physical blending is an effective strategy for tailoring polymeric materials to specific application requirements. However, physically blended mixed plastics waste adds additional barriers in mechanical or chemical recycling. This difficulty arises from the intricate requirement for meticulous sorting and separation of the various polymers in the inherent incompatibility of mixed polymers during recycling. To overcome this impediment, this work furthers the emerging single-monomer - multiple-materials approach through the design of a bifunctional monomer that can not only orthogonally polymerize into two different types of polymers - specifically lactone-based polyester and CO-based polycarbonate - but the resultant polymers and their mixture can also be depolymerized back to the single, original monomer when facilitated by catalysis. Specifically, the lactone/epoxide hybrid bifunctional monomer (BiL) undergoes ring-opening polymerization through the lactone manifold to produce polyester, PE(BiL), and is also applied to ring-opening copolymerization with CO, via the epoxide manifold, to yield polycarbonate, PC(BiL). Remarkably, a one-pot recycling process of a BiL-derived PE/PC blend back to the constituent monomer BiL in >99 % selectivity was achieved with a superbase catalyst at 150 °C, thereby effectively obviating the requirement for sorting and separation typically required for recycling of mixed polymers.
物理共混是一种根据特定应用需求定制聚合物材料的有效策略。然而，物理共混的混合塑料废料在机械回收或化学回收中增加了额外的障碍。这种困难源于在回收过程中混合聚合物固有的不相容性，对各种聚合物进行精细分类和分离的复杂要求。为了克服这一障碍，本研究通过设计一种双功能单体，进一步推进了新兴的单单体-多材料方法，该单体不仅可以正交聚合成两种不同类型的聚合物——特别是内酯基聚酯和CO基聚碳酸酯——而且在催化作用下，所得聚合物及其混合物还可以解聚回单一的原始单体。具体而言，内酯/环氧化物杂化双功能单体（BiL）通过内酯歧管进行开环聚合以生成聚酯PE（BiL），并且还通过环氧化物歧管与CO进行开环共聚以生成聚碳酸酯PC（BiL）。值得注意的是，在150°C下使用超强碱催化剂实现了将BiL衍生的PE/PC共混物一锅法回收为组成单体BiL的过程，选择性>99%，从而有效地消除了混合聚合物回收通常所需的分类和分离要求。
