The development of new chemically recyclable polymers could serve as a means of reducing the plastic pollution and alleviating global energy crisis and monomer design strategy has driven the innovation in this field. In this contribution, α-dimethyl substituted caprolactam (α-DMCL) and γ-dimethyl substituted caprolactam (γ-DMCL) were prepared to evaluate the substitution position effect on chemical recyclability and material performance in polycaprolactam (PCL) system. The introduction of geminal dimethyl substitution to ε-caprolactam (CL) at α and γ position could change the thermal and mechanical properties of the resulting polyamides P(α-DMCL) and P(γ-DMCL). Remarkably, thermal depolymerization of P(γ-DMCL) in presence of potassium caprolactamate (CL-K) could be carried out at 200 °C and converted to γ-DMCL in 91% yield. The recovered γ-DMCL was capable of repolymerization to P(γ-DMCL) without a decrease in reactivity, demonstrating the proof-of-concept recyclability of P(γ-DMCL).

中文翻译：

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通过偕二甲基取代获得可化学回收的聚酰胺

新型化学可回收聚合物的开发可以作为减少塑料污染和缓解全球能源危机的一种手段，单体设计策略推动了该领域的创新。在本论文中，制备了α-二甲基取代己内酰胺（α-DMCL）和γ-二甲基取代己内酰胺（γ-DMCL），以评估取代位置对聚己内酰胺（PCL）体系中化学可回收性和材料性能的影响。在ε-己内酰胺（CL）的α和γ位引入偕二甲基取代可以改变所得聚酰胺P（α-DMCL）和P（γ-DMCL）的热性能和机械性能。值得注意的是，在己内酰胺钾 (CL-K) 存在下，P(γ-DMCL) 的热解聚可以在 200 °C 下进行，并以 91% 的产率转化为 γ-DMCL。回收的 γ-DMCL 能够再聚合为 P(γ-DMCL)，且反应活性不会降低，这证明了 P(γ-DMCL) 的概念验证可回收性。