Zhang Ji, Zhang Haiyan, Ragab Tarek, Wang Weidong, Jin Zhaoyang, Zhu Yingmin, Wang Xiao, Jiang Kyle
School of Mechano-Electronic Engineering, Xidian University, Xi'an, Shaanxi Province, China, 710071.
CityU-Xidian Joint Laboratory of Micro/Nano Manufacturing, Shenzhen, China, 518057.
Langmuir. 2024 Sep 12. doi: 10.1021/acs.langmuir.4c02265.
1,1,2,2-Perfluorodecyltriethoxysilane (PFDTES) is the most widely used coating material with low surface energy and has the potential to be used as a dust-mitigating coating material during lunar landing missions. Graphene can be added to the PFDTES matrix to improve its mechanical properties. In this study, molecular dynamics simulations were performed to investigate the interfacial shear strength and friction mechanism between the PFDTES matrix and graphene. A systematic molecular dynamics (MD) simulation has been performed to calculate the interfacial shear strength of the PFDTES-graphene interface with considering the effect of graphene sliding velocity and vacancy defect density. For a pristine graphene layer with a size of 10 nm × 10 nm, the interfacial force between graphene and the PFDTES matrix is around 3 nN. Like other polymeric materials, the interfacial shear force exhibited stick-slip behavior under loading. The interfacial shear force will start to increase after the graphene starts sliding against the PFDTES matrix and reaches a stable plateau in a very short distance. It has been found that the influence of the interfacial shear strength from the sliding velocity of graphene is minimal. However, a significant increase in the interfacial shear strength has been observed after the graphene defect density increased; i.e., the magnitude of the shear force increased from 3 nN to around 14 nN after the defect density increased from 0% for pristine graphene to 40%. It has been found that vacancy defects will increase the fluctuation in the interfacial shear force, and it is due to not only the increased roughness near defects but also the stretched bonds in graphene under loading according to the distribution of the bond length. This study concluded that interfacial stick-slip behavior also exists in the PFDTES-graphene interface, and vacancy defects will have a significant improvement in the interfacial shear strength.
1,1,2,2-全氟癸基三乙氧基硅烷（PFDTES）是应用最广泛的低表面能涂层材料，有潜力用作月球着陆任务中的减尘涂层材料。可将石墨烯添加到PFDTES基体中以改善其机械性能。在本研究中，进行了分子动力学模拟，以研究PFDTES基体与石墨烯之间的界面剪切强度和摩擦机制。已进行了系统的分子动力学（MD）模拟，以计算考虑石墨烯滑动速度和空位缺陷密度影响的PFDTES-石墨烯界面的界面剪切强度。对于尺寸为10 nm×10 nm的原始石墨烯层，石墨烯与PFDTES基体之间的界面力约为3 nN。与其他聚合物材料一样，界面剪切力在加载下表现出粘滑行为。石墨烯开始相对于PFDTES基体滑动后，界面剪切力将开始增加，并在很短的距离内达到稳定的平台期。已发现，石墨烯滑动速度对界面剪切强度的影响最小。然而，在石墨烯缺陷密度增加后，观察到界面剪切强度显著增加；即，缺陷密度从原始石墨烯的0%增加到40%后，剪切力的大小从3 nN增加到约14 nN。已发现空位缺陷会增加界面剪切力的波动，这不仅是由于缺陷附近粗糙度的增加，还由于根据键长分布，加载下石墨烯中的键被拉伸。本研究得出结论，PFDTES-石墨烯界面也存在界面粘滑行为，空位缺陷将显著提高界面剪切强度。
