Sumiya Yosuke, Tsuji Yuta, Yoshizawa Kazunari
Institute for Materials Chemistry and Engineering and IRCCS, Kyushu University, Nishi-Ku, Fukuoka 819-0395, Japan.
ACS Omega. 2022 May 14;7(20):17393-17400. doi: 10.1021/acsomega.2c01544. eCollection 2022 May 24.
Adhesive strength is known to change significantly depending on the direction of the force applied. In this study, the peel and tensile adhesive forces between the hydroxylated silica (001) surface and epoxy resin are estimated based on quantum chemical calculations. Here, density functional theory (DFT) with dispersion correction is used. In the peel process, the epoxy resin is pulled off from the terminal part, while in the tensile process, the entire epoxy resin is pulled off vertically. As a result of these calculations, the maximum adhesive force in the peel process is decreased to be about 40% of that in the tensile process. The adhesion force-displacement curve for the peeling process shows two characteristic peaks corresponding to the process where the adhesive molecule horizontally oriented to the surface shifts to a vertical orientation to the surface and the process where the vertical adhesive molecule is dissociated from the surface. Force decomposition analysis is performed to further understand the peel adhesion force; the contribution of the dispersion force is found to be slightly larger than that of the DFT force. This feature is common to the tensile process as well. Each force in the peel process is about 40% smaller than the corresponding force in the tensile process.
众所周知，粘附力会根据所施加力的方向而发生显著变化。在本研究中，基于量子化学计算估算了羟基化二氧化硅（001）表面与环氧树脂之间的剥离粘附力和拉伸粘附力。在此，使用了具有色散校正的密度泛函理论（DFT）。在剥离过程中，环氧树脂从末端部分被拉开，而在拉伸过程中，整个环氧树脂垂直被拉开。这些计算的结果是，剥离过程中的最大粘附力降低至拉伸过程中最大粘附力的约40%。剥离过程的粘附力 - 位移曲线显示出两个特征峰，分别对应于粘附分子从水平于表面的取向转变为垂直于表面的取向的过程以及垂直粘附分子从表面解离的过程。进行力分解分析以进一步理解剥离粘附力；发现色散力的贡献略大于DFT力的贡献。这一特征在拉伸过程中也是常见的。剥离过程中的每种力比拉伸过程中相应的力小约40%。
