The effect of catalyst strength on polyester–alcohol dynamic covalent exchange was systematically studied using Brønsted acids and a low-T_g poly(4-methylcaprolactone) vitrimer formulation. Relaxation times, activation energies, and Arrhenius prefactors are correlated with pK_a. Strong protic acids induce facile network relaxation at 25 °C on the order of 10⁴–10⁵ s, significantly faster than Lewis acid alternatives that function only above 100 °C. Activation energies span 49–67 kJ/mol and increase as pK_a decreases. The opposite trend is observed with the Arrhenius prefactor. We anticipate that the quantitative understanding of Brønsted acid effects disclosed herein will be of utility in future studies that exploit acid-catalyzed dynamic covalent bond exchange.

中文翻译：

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聚酯动态共价网络中的布朗斯台德酸催化交换

使用布朗斯台德酸和低T _g聚 (4-甲基己内酯) vitrimer 配方系统地研究了催化剂强度对聚酯-醇动态共价交换的影响。弛豫时间、活化能和 Arrhenius 前因子与 p K _a相关。强质子酸在 25 °C 下诱导容易的网络松弛，大约为 10 ⁴ –10 ⁵ s，明显快于仅在 100 °C 以上起作用的路易斯酸替代品。活化能范围为 49–67 kJ/mol，并随着 p K _{a 的增加而增加}减少。Arrhenius prefactor 观察到相反的趋势。我们预计，本文公开的对布朗斯台德酸效应的定量理解将在未来利用酸催化的动态共价键交换的研究中有用。