Felician Francesco, Antonopoulou Maria-Nefeli, Truong Nghia P, Kroeger Asja A, Coote Michelle L, Jones Glen R, Anastasaki Athina
Laboratory of Sustainable Polymers, Department of Materials, ETH Zürich Vladimir-Prelog-Weg 5 8093 Zürich Switzerland
Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park South Australia 5042 Australia.
Polym Chem. 2025 Mar 19;16(16):1822-1828. doi: 10.1039/d5py00212e. eCollection 2025 Apr 15.
Reversible addition-fragmentation chain-transfer (RAFT) depolymerization represents an attractive and low-temperature chemical recycling methodology enabling the near-quantitative regeneration of pristine monomer. Yet, several mechanistic aspects of the process remain elusive. Herein, we shine a light on the RAFT depolymerization mechanism by elucidating the effect of pendant side chains on the depolymerization kinetics. A systematic increase of the number of carbons on the side chain, or the number of ethylene glycol units, revealed a significant rate acceleration. Notably, radical initiator addition during the depolymerization of poly(methyl methacrylate) and poly(hexyl methacrylate) resulted in rate equilibration, indicating that chain activation is the rate-determining step in RAFT depolymerization. Moreover, incorporation of a low DP of hexyl monomer as the second block of poly(methyl methacrylate) led to comparable rates with poly(hexyl methacrylate) homopolymer, confirming the rate determining step. Computational investigations further corroborate this finding, revealing that chain-end fragmentation is energetically more favorable in longer-side-chain methacrylates, which accounts for the experimentally observed rate acceleration. These insights not only deepen our understanding of depolymerization but also pave the way for developing more efficient and customizable depolymerization systems.
可逆加成-断裂链转移（RAFT）解聚是一种有吸引力的低温化学循环方法，能够近乎定量地再生原始单体。然而，该过程的几个机理方面仍然难以捉摸。在此，我们通过阐明侧链对解聚动力学的影响，揭示了RAFT解聚机制。侧链上碳原子数量或乙二醇单元数量的系统性增加显示出显著的速率加速。值得注意的是，在聚甲基丙烯酸甲酯和聚己基丙烯酸甲酯解聚过程中添加自由基引发剂导致速率平衡，这表明链活化是RAFT解聚中的速率决定步骤。此外，将低聚合度的己基单体作为聚甲基丙烯酸甲酯的第二嵌段引入，导致其速率与聚己基丙烯酸甲酯均聚物相当，证实了速率决定步骤。计算研究进一步证实了这一发现，揭示了链端断裂在较长侧链甲基丙烯酸酯中在能量上更有利，这解释了实验观察到的速率加速现象。这些见解不仅加深了我们对解聚的理解，也为开发更高效、可定制的解聚系统铺平了道路。
