Solvent-Free Chemical Recycling of Polymethacrylates made by ATRP and RAFT polymerization: High-Yielding Depolymerization at Low Temperatures
Solvent-Free Chemical Recycling of Polymethacrylates made by ATRP and RAFT polymerization: High-Yielding Depolymerization at Low Temperatures
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DOI：
10.1002/anie.202309116
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发表时间：
2023-08-11
影响因子：
16.6
通讯作者：
Anastasaki，Athina
中科院分区：
文献类型：
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作者：
Whitfield，Richard;Jones，Glen R.;Anastasaki，Athina
尽管受控自由基聚合是制造精密聚合物材料的极好工具，但是尽管化学回收的重要性，但是对回收起始单体的过程的逆转的探索要少得多。在这里，我们研究了在相同条件下RAFT和ATRP合成的聚合物的本体解聚。RAFT合成的聚合物经历相对低温的无溶剂解聚，由于RAFT端基部分原位转化为大分子单体。相反，ATRP合成的聚合物只能在显著更高的温度（>350 °C）下通过无规主链断裂而解聚。为了在更低的温度下帮助更完全的解聚，我们进行了一种简单和定量的端基修饰策略，其中ATRP和RAFT端基都成功转化为大分子单体。大分子单体引发较低温度的本体解聚，在150 °C下开始，产生高达90%的单体再生。该方法的通用性通过可扩展的解聚（约10g起始聚合物）证明，回收84%的完整起始单体，其随后可用于进一步聚合。 这项工作提出了一种新的低能量方法来解聚受控自由基聚合物，并创造了许多未来的机会，因为高产，无溶剂和可扩展的解聚方法正在寻求。
Although controlled radical polymerization is an excellent tool to make precision polymeric materials, reversal of the process to retrieve the starting monomer is far less explored despite the significance of chemical recycling. Here, we investigate the bulk depolymerization of RAFT and ATRP‐synthesized polymers under identical conditions. RAFT‐synthesized polymers undergo a relatively low‐temperature solvent‐free depolymerization back to monomer thanks to the partial in situ transformation of the RAFT end‐group to macromonomer. Instead, ATRP‐synthesized polymers can only depolymerize at significantly higher temperatures (>350 °C) through random backbone scission. To aid a more complete depolymerization at even lower temperatures, we performed a facile and quantitative end‐group modification strategy in which both ATRP and RAFT end‐groups were successfully converted to macromonomers. The macromonomers triggered a lower temperature bulk depolymerization with an onset at 150 °C yielding up to 90 % of monomer regeneration. The versatility of the methodology was demonstrated by a scalable depolymerization (≈10 g of starting polymer) retrieving 84 % of the starting monomer intact which could be subsequently used for further polymerization. This work presents a new low‐energy approach for depolymerizing controlled radical polymers and creates many future opportunities as high‐yielding, solvent‐free and scalable depolymerization methods are sought.