Yamamoto Satoru, Kuwahara Riichi, Tanaka Keiji
Centre for Polymer Interface and Molecular Adhesion Science, Kyushu University, Fukuoka 819-0395, Japan.
Soft Matter. 2021 Jul 7;17(25):6073-6080. doi: 10.1039/d1sm00529d. Epub 2021 Jun 16.
Although an epoxy resin is a stable material, it absorbs moisture over a long period of time, causing deterioration of its material properties. We here applied a full-atomistic molecular dynamics (MD) simulation to study where water molecules exist in an epoxy resin and how they dynamically behave. First, the curing reaction was simulated to obtain a network structure so that the time course of the density, and thereby the free space, in the resin were obtained. The results made it possible to discuss the formation and size distribution of the free spaces which were not connected to each other. Then, a few percent of water were inserted into the free space of the cured epoxy resin to examine the location and dynamics of their molecules. We found that several water molecules were clustered at a preferred site, where hydrogen bonds can be formed with hydroxy, ether and amino groups of the network, in the free space, and they heterogeneously moved from there to other sites.
尽管环氧树脂是一种稳定的材料，但它在长时间内会吸收水分，导致其材料性能恶化。我们在此应用全原子分子动力学（MD）模拟来研究水分子在环氧树脂中的存在位置以及它们的动态行为。首先，模拟固化反应以获得网络结构，从而得到树脂中密度随时间的变化过程，进而得到自由空间。这些结果使得我们能够讨论彼此不相连的自由空间的形成和尺寸分布。然后，将百分之几的水引入固化环氧树脂的自由空间中，以研究水分子的位置和动态。我们发现，几个水分子聚集在自由空间中的一个优先位置，在那里它们可以与网络中的羟基、醚基和氨基形成氢键，并且它们从那里不均匀地移动到其他位置。
