Protonation of Strained Epoxy Resin under Wet Conditions via First-Principles Calculations Using the H+-Shift Method
Protonation of Strained Epoxy Resin under Wet Conditions via First-Principles Calculations Using the H+-Shift Method
复制标题
使用 H 位移法通过第一性原理计算在潮湿条件下对应变环氧树脂进行质子化
DOI：
10.1021/acs.jpcb.3c00401
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Uranagase Masayuki
中科院分区：
文献类型：
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作者：
Ogata Shuji;Uranagase Masayuki
胶粘剂粘接中的一个重大挑战是在潮湿条件下拉伸胶粘剂的加速断裂，这就是所谓的粘合破坏。一组常用的粘合剂由胺固化的环氧树脂组成。基于无张力树脂在水中的去质子化自由能计算，最近有人提出，在中性或酸性条件下，这些胶粘剂可以通过起源于质子化胺基团的断裂而失效[J.Phys.化学。B2021,125,8989-8996]。在这项研究中，我们通过设计一种适用于应变材料的稳健的第一原理质子化计算方法，全面研究了拉伸和压缩条件下胺基质子化的程度。结果表明，在298K时，氨基在中性水中部分质子化，当环氧树脂在水中被较大程度拉伸时，胺基质子化，反之亦然。这些发现支持了拉伸胺固化环氧树脂中胺基质子化导致粘结失效的物理化学原因。
A significant challenge in adhesive bonding is the accelerated breaking of stretched adhesives under wet conditions, which is known as cohesive failure. One group of commonly used adhesives consists of the amine-cured epoxy resins. Based on deprotonation free-energy calculations of the unstrained resin in water, it has recently been proposed that these adhesives can undergo failure through breakage originating at the protonated amine group under neutral or acidic conditions [J. Phys. Chem. B2021,125, 8989–8996]. In this study, we comprehensively investigated the degree of protonation of the amine group under both stretched and compressed conditions by devising a robust first-principles protonation calculation method applicable to strained materials. It was found that the amine group was partially protonated in neutral water at 298 K and that the amine group was protonated when the epoxy resin was stretched to a greater extent in water, and vice versa. These findings support the physicochemical cause of cohesive failure due to protonation of the amine group in the stretched amine-cured epoxy resins.