电润湿作用下水在石墨烯表面流动的边界滑移及界面摩擦  

Boundary slip and interfacial friction properties of confined-water flow on graphene under electrowetting

作　　者：张忠强[1,2,3] 叶宏飞[3] 程广贵[1,2] 郑勇刚[3] 丁建宁[1,2] 凌智勇[1] 

机构地区：[1]江苏大学微纳米科学技术中心,江苏镇江212013 [2]江苏省太阳能电池材料与技术重点实验室,江苏常州213164 [3]大连理工大学工业装备结构分析国家重点实验室,辽宁大连116023

出　　处：《新型炭材料》2013年第6期475-479,共5页New Carbon Materials

基　　金：国家自然科学基金(11102074;51005103;11302037;11272003);江苏省自然科学基金(BK2011463);中国博士后基金(2011M501169)及特别资助(2013T60503);江苏大学高级专业人才启动基金(11JDG024)~~

摘　　要：采用分子动力学方法结合流体边界滑移理论对电润湿作用下水在石墨烯表面流动的边界滑移及摩擦特性进行数值模拟和理论分析。采用石墨烯-水Couette剪切模型,获取电润湿作用下和不带电情况下的剪切速率轮廓、石墨烯表面的剪切应力、边界滑移速率、滑移长度及界面摩擦系数,着重研究界面滑移长度和界面摩擦系数与剪切应变率之间的变化。结果表明:当剪切应变率超过临界剪切应变率时,滑移长度迅速增加,且电润湿作用下的临界剪切应变率明显高于不带电情况下的临界剪切应变率,而界面摩擦系数随着剪切应变率的增大而减小;石墨烯电润湿作用明显增强了石墨烯-水界面的摩擦。无论在电润湿作用下还是不带电情况下,石墨烯-水Couette模型中水的黏性系数与剪切应变率无关。The boundary slip and interracial friction properties of confined-water flow on two parallel single-layer graphene sheets with a separation of 6 nm under electrowetting conditions were investigated by molecular dynamics simulation and boundary slip the- ory. For both electrowetted and uncharged graphenes, the flow velocity profiles perpendicular to the flow direction, shear stress, boundary slip velocity, slip length and interfacial friction coefficient were obtained with a graphene-water Couette flow model. Re- suits show that the slip length increases abruptly when the shear rate is above a critical value. The critical shear rate in the elec- trowetted graphenes is obviously larger than that in uncharged ones. The interfacial friction coefficient between graphene and water decreases with the shear rate and is increased by electrowetting the graphenes. The water viscosity is independent of the shear rate in both eletrowetted and uncharged graphenes.

关 键 词：石墨烯 电润湿 水 边界滑移 界面摩擦 

分 类 号：O613.71[理学—无机化学]