Saito Keita, Türel Tankut, Eisenreich Fabian, Tomović Željko
Polymer Performance Materials Group, Department of Chemical Engineering and Chemistry and Institute for Complex Molecular Systems, Eindhoven University of Technology, 5600 MB, Eindhoven (The, Netherlands.
ChemSusChem. 2023 Nov 8;16(21):e202301017. doi: 10.1002/cssc.202301017. Epub 2023 Aug 21.
Chemical recycling offers a promising solution for the end-of-life treatment of synthetic polymers. However, the efficient recovery of well-defined recycled building blocks continues to be a major challenge, especially for crosslinked thermosets. Here, we developed vanillin-based polymer networks functionalized with dual-cleavable imine and acetal bonds that facilitate chemical recycling to primary building blocks and their convenient separation at the molecular level. A library of crosslinked poly(imine-acetal)s was synthesized by combining the in-bulk synthesized liquid di-vanillin acetal monomer (DVA) with commercially available liquid di- and triamines under solvent-free conditions. These thermosets showed tailor-made thermal and mechanical properties along with outstanding chemical recyclability. Under aqueous acidic conditions, poly(imine-acetal)s selectively and completely disintegrate into small molecules. During the polymer design stage, these compounds were carefully selected to enable facile separation without tedious techniques. As a result, the primary building blocks were isolated in high yields and purity and immediately reused to produce fresh polymers with identical thermomechanical properties. Since our "design for recycling" concept aims at obtaining the primary building blocks rather than monomers after depolymerization, a plethora of possibilities are unlocked to utilize these chemical resources, including closed-loop recycling as portrayed.
化学回收为合成聚合物的报废处理提供了一个有前景的解决方案。然而，高效回收结构明确的再生结构单元仍然是一个重大挑战，尤其是对于交联热固性材料而言。在此，我们开发了基于香草醛的聚合物网络，其通过双可裂解的亚胺键和缩醛键进行功能化，这有助于将化学回收转化为主要结构单元，并在分子水平上实现它们的便捷分离。通过在无溶剂条件下将本体合成的液体二香草醛缩醛单体（DVA）与市售的液体二胺和三胺相结合，合成了一系列交联聚（亚胺 - 缩醛）。这些热固性材料展现出定制的热性能和机械性能以及出色的化学可回收性。在水性酸性条件下，聚（亚胺 - 缩醛）选择性地且完全分解为小分子。在聚合物设计阶段，仔细选择这些化合物以实现无需繁琐技术的便捷分离。结果，主要结构单元以高收率和高纯度被分离出来，并立即重新用于生产具有相同热机械性能的新鲜聚合物。由于我们的“回收设计”概念旨在解聚后获得主要结构单元而非单体，因此开启了利用这些化学资源的众多可能性，包括如所描述的闭环回收。
