液态Ag薄膜在修饰的石墨烯表面的形态演变及其界面性质

Interfacial properties and morphological evolution of liquid Ag film on the modified graphene

利用分子动力学方法模拟了纳米尺度下液态Ag在表面修饰的石墨烯表面的界面现象.研究表明:Ag液滴在石墨烯表面发生反润湿现象,势函数参数、基体表面结构、Ag液膜厚度以及液膜形状对液膜的润湿性及形态变化均有显著影响,这些条件的改变都将会影响液滴的反润湿性,使液滴的脱离时间和脱离速度发生改变.此外,通过设置双液膜体系,研究了两液膜的桥接、断裂或融合、脱离过程.该研究对深入认识超疏水表面以及如何控制液滴的收缩和融合具有重要意义.

The interfacial wettability and morphological evolution of liquid on a solid substrate,as natural phenomena,have received great attention in recent years.Although much work has been done to study this process,existing studies mainly focus on the wetting properties of water.Therefore,in this paper,we use molecular dynamics simulation method to study the interfacial phenomena of the nanoscale liquid silver on graphene,whose surface has been modified.By making different comparisons,such as Lennard-Jones（LJ） potential parameters,the surface structures of substrates,the thickness values of films and the shapes of films,the influences of these variables on wetting properties of liquid silver on graphene are studied.The results show that the dewetting of liquid silver occurs on graphene,implying that the wettability of liquid silver is weak,and that the potential parameters,the surface structure of substrates,the thickness of film and the shape of film have great influences on the wettability and morphology evolution of film： the change of these factors can affect the dewetting properties of liquid silver,which is evident by the detachment time and detachment speed.With the increase of LJ potential parameters,the detachment time is larger while the contraction speed and the detachment speed are smaller.Compared with the detachment times on different carbon-based substrates,the detachment time is small on the pillared graphene,followed by the vertical carbon nanotube,and the detachment time is large on the graphene.With increasing the thickness of the film,the detachment time becomes larger.The detachment time of the circle film is smaller than those of the regular hexagon film and square film,manifesting that the films with smooth boundary are beneficial to separating from the substrate.Moreover,by setting a system of two liquid films,we study the formation of silver bridge of two films and the fracture or fusion of the bridge.When two liquid films initially contact each other,the liquid bridge forms.However,the growth behaviors of liquid bridges are different from each other,some liquid bridges become slim and finally fractures,other liquid bridges do not fracture and help two droplets form one bigger drop.These different behaviors mainly depend on the size of film.This study is very valuable for well understanding the superhydrophobic surfaces and the morphological evolutions of Ag films on the graphene.Furthermore,these findings can provide an effective method to control the dewetting behavior of liquid Ag and the fracture or fusion of the two liquid drops by tuning the size of the films.