Laboratory of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, Zurich 8093, Switzerland.
Research School of Chemistry, Australian National University, Canberra 2601, Australian Capital Territory, Australia.
J Am Chem Soc. 2022 Mar 16;144(10):4678-4684. doi: 10.1021/jacs.2c00963. Epub 2022 Feb 25.
The ability to reverse controlled radical polymerization and regenerate the monomer would be highly beneficial for both fundamental research and applications, yet this has remained very challenging to achieve. Herein, we report a near-quantitative (up to 92%) and catalyst-free depolymerization of various linear, bulky, cross-linked, and functional polymethacrylates made by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Key to our approach is to exploit the high end-group fidelity of RAFT polymers to generate chain-end radicals at 120 °C. These radicals trigger a rapid unzipping of both conventional (e.g., poly(methyl methacrylate)) and bulky (e.g., poly(oligo(ethylene glycol) methyl ether methacrylate)) polymers. Importantly, the depolymerization product can be utilized to either reconstruct the linear polymer or create an entirely new insoluble gel that can also be subjected to depolymerization. This work expands the potential of polymers made by controlled radical polymerization, pushes the boundaries of depolymerization, offers intriguing mechanistic aspects, and enables new applications.
能够反转可控自由基聚合并使单体再生对于基础研究和应用都将是非常有益的，但这一直是非常具有挑战性的。在此，我们报道了通过可逆加成-断裂链转移（RAFT）聚合得到的各种线性、大体积、交联和功能化的聚甲基丙烯酸酯的近乎定量（高达 92%）且无需催化剂的解聚。我们方法的关键是利用 RAFT 聚合物的高端基保真度在 120°C 下生成链末端自由基。这些自由基引发常规聚合物（例如聚（甲基丙烯酸甲酯））和大体积聚合物（例如聚（聚乙二醇甲基醚甲基丙烯酸酯））的快速解拉链式反应。重要的是，解聚产物可用于重建线性聚合物或形成全新的不溶性凝胶，该凝胶也可进行解聚。这项工作扩展了由受控自由基聚合得到的聚合物的潜在用途，推动了解聚的边界，提供了有趣的机理方面，并为新的应用提供了可能。
