Institute for Materials Chemistry and Engineering and IRCCS , Kyushu University , Nishi-Ku, Fukuoka 819-0395 , Japan.
School of Liberal Arts and Sciences , Daido University , Minami-Ku, Nagoya 457-8530 , Japan.
Langmuir. 2018 Nov 27;34(47):14428-14438. doi: 10.1021/acs.langmuir.8b02490. Epub 2018 Nov 12.
Adhesion is one of the most interesting subjects in interface phenomena from the viewpoint of wide-range applications as well as basic science. Interfacial water has significant effects on coatings, adhesives, and fiber-reinforced polymer composites, often causing adhesion loss. The way of thinking based on quantum mechanics is essential for a better understanding of physical and chemical properties of adhesive interfaces. In this work, the molecular mechanism of the adhesion interaction between epoxy resin and hydroxylated alumina surface in the presence of interfacial water molecules is investigated by using density-functional tight-binding calculations. Periodic slab model calculations demonstrate that hydrogen bond is an important factor at the adhesion interface. Effects of interfacial water molecules located between epoxy resin and hydroxylated alumina surface are assessed by using a dry model without interfacial water and wet models with water layers of 3, 6, and 9 Å thicknesses. Interesting first- and second-layer structures are observed in the distribution of interfacial water molecules in the tight space between the adhesive and adherend. Energy plots with respect to the displacement of epoxy resin from the alumina surface are nicely approximated by the Morse potential. The adhesion force and stress are theoretically obtained by differentiating the potential curve with respect to the displacement of epoxy resin. Computational results show that the adhesion force and stress are significantly weakened with an increase in the thickness of interfacial water layer. Thus, interfacial water molecules have a clue as to the role of water in the loss of adhesion.
从广泛应用和基础科学的角度来看，界面现象中的附着是最有趣的课题之一。界面水对涂料、胶粘剂和纤维增强聚合物复合材料有显著的影响，常常导致附着损失。基于量子力学的思维方式对于更好地理解附着界面的物理和化学性质是必不可少的。在这项工作中，使用密度泛函紧束缚计算研究了存在界面水分子时环氧树脂与羟基化氧化铝表面之间的附着相互作用的分子机制。周期性平板模型计算表明氢键是附着界面的一个重要因素。通过使用没有界面水分子的干燥模型和具有 3、6 和 9 Å 厚度的水层的湿模型，评估了位于环氧树脂和羟基化氧化铝表面之间的界面水分子的影响。在胶粘剂和被粘物之间的紧密空间中，观察到界面水分子的分布中存在有趣的第一层和第二层结构。与环氧树脂从氧化铝表面的位移有关的能量图很好地被 Morse 势近似。通过对环氧树脂位移的势曲线求导，可以得到附着力和应力。计算结果表明，附着力和应力随界面水层厚度的增加而显著减弱。因此，界面水分子为水在附着损失中的作用提供了线索。
