Department of Applied Physics, COMP Centre of Excellence, Aalto University, P.O. Box 11100, 00076 Aalto, Espoo, Finland.
Supercomputing Center of CAS, Computer Network Information Center, Chinese Academy of Sciences, Beijing 100190, China.
Phys Rev Lett. 2015 Mar 6;114(9):095502. doi: 10.1103/PhysRevLett.114.095502. Epub 2015 Mar 5.
We study the effect of atomic-scale surface-lubricant interactions on nanoscale boundary-lubricated friction by considering two example surfaces-hydrophilic mica and hydrophobic graphene-confining thin layers of water in molecular dynamics simulations. We observe stick-slip dynamics for thin water films confined by mica sheets, involving periodic breaking-reforming transitions of atomic-scale capillary water bridges formed around the potassium ions of mica. However, only smooth sliding without stick-slip events is observed for water confined by graphene, as well as for thicker water layers confined by mica. Thus, our results illustrate how atomic-scale details affect the wettability of the confining surfaces and consequently control the presence or absence of stick-slip dynamics in nanoscale friction.
我们通过分子动力学模拟研究了原子尺度表面润滑剂相互作用对纳米尺度边界润滑摩擦的影响，考虑了两种示例表面——亲水性云母和疏水性石墨烯——来限制薄水层。我们观察到亲水云母片限制的薄水膜的粘滑动力学，涉及云母钾离子周围形成的原子尺度毛细水桥的周期性断裂-再形成转变。然而，对于石墨烯限制的水以及云母限制的较厚水层，仅观察到无粘滑事件的平滑滑动。因此，我们的结果说明了原子尺度细节如何影响约束表面的润湿性，并因此控制纳米摩擦中粘滑动力学的存在与否。
