Nakamura Shin, Tsuji Yuta, Yoshizawa Kazunari
Institute for Materials Chemistry and Engineering and IRCCS, Kyushu University, Nishi-ku, Fukuoka 819-0395, Japan.
Langmuir. 2021 Dec 21;37(50):14724-14732. doi: 10.1021/acs.langmuir.1c02653. Epub 2021 Dec 6.
The presence of adsorbed water on hydrophilic solid surfaces should be taken into account, especially in humid environments. It significantly reduces the adhesive strength between the epoxy resin and the adherend surface. Here, the adhesion structure of interfacial water sandwiched between bisphenol A epoxy resin and a hydroxylated silica (001) surface is investigated with microsecond molecular dynamics simulations. Specifically, interfacial water layers with initial thicknesses of 7.5, 10, and 20 Å are modeled. The density curves of water and the diglycidyl ether of bisphenol A show that at room temperature, the surface of the silica with hydroxyl groups is completely covered with a thick layer of water. For water layers thinner than 10 Å, the density of epoxy resin on the silica surface increases when the system is heated and does not return to the original density when the system is cooled. Furthermore, calculation of the interaction energy revealed that the exclusion of water from the hydroxylated surface by epoxy resin during heating can contribute to the increase in the adhesive interaction between the epoxy resin and the silica surface with hydroxyl groups.
应考虑亲水性固体表面吸附水的存在，尤其是在潮湿环境中。它会显著降低环氧树脂与被粘物表面之间的粘合强度。在此，通过微秒级分子动力学模拟研究了夹在双酚A环氧树脂和羟基化二氧化硅（001）表面之间的界面水的粘附结构。具体而言，对初始厚度为7.5、10和20 Å的界面水层进行了建模。水和双酚A二缩水甘油醚的密度曲线表明，在室温下，带有羟基的二氧化硅表面完全被一层厚厚的水覆盖。对于厚度小于10 Å的水层，当系统加热时，二氧化硅表面上环氧树脂的密度增加，而当系统冷却时不会恢复到原始密度。此外，相互作用能的计算表明，加热过程中环氧树脂将水从羟基化表面排挤出去，这有助于增加环氧树脂与带有羟基的二氧化硅表面之间的粘附相互作用。
