楔形铜基底-单层石墨烯覆层表面液滴自驱动研究  

Uni-directional self-driving of water droplets on monolayer graphene-covered wedge-shaped copper substrate

作　　者：张福建 陈悦[1] 高翔[1] 刘珍[2] 张忠强[1,3] Zhang Fu-Jian;Chen Yue;Gao Xiang;Liu Zhen;Zhang Zhong-Qiang(Institute of Intelligent Flexible Mechatronics,Jiangsu University,Zhenjiang 212013,China;School of Naval Architecture and Ocean Engineering,Jiangsu University of Science and Technology,Zhenjiang 212003,China;Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering,Changzhou University,Changzhou 213164,China)

机构地区：[1]江苏大学智能柔性机械电子研究院,镇江212013 [2]江苏科技大学船舶与海洋工程学院,镇江212003 [3]常州大学,江苏省光伏科学与工程协同创新中心,常州213164

出　　处：《物理学报》2021年第20期12-20,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11872192,22005124);江苏省研究生科研与实践创新计划(批准号:SJKY19_2535)资助的课题.

摘　　要：液滴在织构基底上的自驱动对于理解一些生物表面水的定向运输和自清洁具有重要意义.本文提出了一种楔形铜基底-单层石墨烯覆层结构,实现了水滴从楔形基底尖端向宽端的定向快速自驱动.运用分子动力学方法研究了液滴在织构基底上的自驱动行为,结果表明,受基底表面润湿梯度和Young-Laplace压力梯度驱动的水滴最大速度可达73.8 m/s.能量变化规律表明,液滴势能和液滴与基底之间的相互作用能存在竞争关系,使得液滴与基底之间的相互作用能有部分转化为液滴势能,部分作用于液滴驱动.从理论上给出了楔形基底上液滴的最大位移与楔形基底角度、基底润湿性和液滴表面张力之间的关系,通过分析微纳尺度楔形基底宽度的非连续线性增加对液滴自驱动的影响,解释了液滴最大位移的理论值与模拟值的差异.此外,发现了尺寸较小的液滴更易获得较大的自驱动速度,分析了高速运动的小液滴在无润湿梯度基底上的长距离减速运动对液滴位移规律的影响,明确了楔形基底两侧悬浮状态的石墨烯对增强液滴输运效率的作用机制.研究结果将对实现液滴自驱动的单层石墨烯覆盖的功能织构表面设计具有理论指导意义.The self-driving of water droplets on textured substrate is momentous for understanding the directional transport of water on biological surface.In this paper,a novel design of monolayer graphene-covered wedge-shaped copper substrate(GWCS)is put forward to realize the directional and ultrafast spontaneous driving of water droplets from the tip of the wedge-shaped substrate to the wide end.The self-driving behaviors of water droplets on GWCS are studied by classical molecular dynamics.The results show that the maximum spontaneous driving velocity of water droplet driven by surface wetting gradient and Young-Laplace pressure gradient can reach 73.8 m/s.The law of energy variation during the whole droplet self-driving on GWCS indicates that there is a competitive relationship between the potential energy of water droplet and the interaction energy between the droplet and GWCS,i.e.the interaction energy between water droplet and GWCS is partially converted into the potential energy of water droplet.The relationship of the maximum displacement of water droplet with the wedge angle,wettability of GWCS and the droplet surface tension is proposed in theory,and the influence of the discontinuous linear increase of the wedge-shaped substrate width on a nanoscale on the self-driving is analyzed and used to explain the little difference between the theoretical and simulation results.Furthermore,a smaller droplet is easier to obtain larger spontaneous driving velocity,and the influence of long-distance decelerating motion of high-speed small droplet on the non-wetting gradient substrate on the droplet displacement law is clarified.Finally,the mechanism of graphene suspended on both sides of the wedge-shaped copper structure to enhance the droplet transport efficiency is determined.The results will have theoretical significance in designing the functional texture surface covered by monolayer graphene to realize droplet self-driving.

关 键 词：自驱动 单层石墨烯 楔形铜基底 分子动力学 

分 类 号：TB306[一般工业技术—材料科学与工程]