Saito Takamasa, Shoji Eita, Kubo Masaki, Tsukada Takao, Kikugawa Gota, Surblys Donatas
Department of Chemical Engineering, Tohoku University, 6-6-07 Aramaki, Aoba-ku, Sendai 980-8579, Japan.
Department of Mechanical Systems Engineering, Tohoku University, 6-6-01 Aramaki, Aoba-ku, Sendai 980-8579, Japan.
J Chem Phys. 2021 Mar 21;154(11):114703. doi: 10.1063/5.0040900.
Advancing the practical applications of surface-modified nanoparticles requires that their dispersion in solvents can be controlled. The degree of dispersion depends on the affinity between surface-modified nanoparticles and solvents, which can be quantified using the work of adhesion at the interface. Herein, the affinity between a surface-modified inorganic solid and an organic solvent was evaluated by calculating the work of adhesion at the interface. The phantom-wall method, which is a thermodynamic route for evaluating the work of adhesion at an interface using molecular dynamics simulations, was applied to the decanoic acid-modified AlO/hexane interface. Molecular dynamics simulations were performed for flat interface systems to focus on the interactions between substances that affect the affinity on the surface. As a result, the surface coverage of decanoic acid was found to affect the work of adhesion, with a maximum value of 45.66 ± 0.75 mJ/m at a surface coverage of 75%. An analysis of the mass density profiles of AlO, decanoic acid, and hexane in the vicinity of the interface showed that the increase in the work of adhesion with the surface coverage was due to the penetration of hexane molecules into the decanoic acid layer on the AlO surface. At a surface coverage of 75%, some hexane molecules were trapped in the layer of oriented decanoic acid molecules. These results suggested that the interfacial affinity can be enhanced by controlling the surface modification so that the solvent can penetrate the layer of the modifier.
推进表面改性纳米颗粒的实际应用需要能够控制它们在溶剂中的分散情况。分散程度取决于表面改性纳米颗粒与溶剂之间的亲和力，这可以通过界面处的粘附功来量化。在此，通过计算界面处的粘附功来评估表面改性无机固体与有机溶剂之间的亲和力。幻壁法是一种利用分子动力学模拟评估界面粘附功的热力学途径，被应用于癸酸改性的AlO/己烷界面。对平面界面系统进行了分子动力学模拟，以关注影响表面亲和力的物质之间的相互作用。结果发现，癸酸的表面覆盖率会影响粘附功，在表面覆盖率为75%时，最大值为45.66±0.75 mJ/m。对界面附近AlO、癸酸和己烷的质量密度分布分析表明，粘附功随表面覆盖率的增加是由于己烷分子渗透到AlO表面的癸酸层中。在表面覆盖率为75%时，一些己烷分子被困在定向癸酸分子层中。这些结果表明，可以通过控制表面改性来增强界面亲和力，使溶剂能够渗透到改性剂层中。
