十二烷基硫酸钠水溶液液滴在微凹槽阵列PDMS表面上的电润湿行为实验研究  

Experimental Investigation of Electrowetting of Aqueous Sodium Dodecyl Sulfate Droplets on Micro-grooved Non-wetting Surfaces

作　　者：廖洋波 黄先富 卢应发 余迎松 LIAO Yang-bo;HUANG Xian-fu;LU Ying-fa;YU Ying-song(School of Civil Engineering,Architecture and Environment,Geotechnical and Ecological Restoration of Rivers and Lakes,Hubei University of Technology,Wuhan 430068,China;Key Laboratory of Intelligent Health Perception and Ecological Restoration of Rivers and Lakes,Geotechnical and Ecological Restoration of Rivers and Lakes,Hubei University of Technology,Wuhan 430068,China;Innovation Demonstration Base of Ecological Environment,Geotechnical and Ecological Restoration of Rivers and Lakes,Hubei University of Technology,Wuhan 430068,China;State Key Laboratory of Nonlinear Mechanics,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China;Guangdong Aerospace Research Academy(Nansha),Guangzhou 511458,China)

机构地区：[1]湖北工业大学土木建筑与环境学院,武汉430068 [2]湖北工业大学河湖健康智慧感知与生态修复教育部重点实验室,武汉430068 [3]湖北工业大学生态环境岩土与河湖生态修复学科引智创新示范基地,武汉430068 [4]中国科学院力学研究所非线性力学国家重点实验室,北京100190 [5]广东空天科技研究院(南沙),广州511458

出　　处：《表面技术》2023年第12期178-187,共10页Surface Technology

基　　金：国家自然科学基金(11572114);生态环境岩土与河湖生态修复学科引智创新示范基地(2020EJB004);广东省基础与应用基础研究基金(2023A1515011784);广东省高水平创新研究院项目(2020B0909010003)。

摘　　要：目的研究十二烷基硫酸钠(Sodium dodecyl sulfate,SDS)水溶液液滴在微凹槽阵列聚二甲基硅氧烷(Polydimethylsiloxane,PDMS)表面的电润湿行为特征。方法采用注入析出法,测量含KCl的SDS水溶液液滴在微凹槽阵列非浸润表面的接触角滞后。通过施加直流电压,研究SDS浓度和表面粗糙度对含KCl的SDS水溶液液滴的电润湿行为的影响。结果微凹槽阵列非浸润表面表现出较强的润湿各向异性,与平行于微凹槽方向上的表观接触角(110°≤θe≤141°)、前进角(116°≤θa≤144°)和后退角(99°≤θr≤137°)相比,垂直于微凹槽方向上的表观接触角(142°≤θe≤165°)、前进角(159°≤θa≤177°)和后退角(118°≤θr≤140°)普遍更大。当表面固定时,水溶液液滴电润湿的启动电压和饱和电压,以及发生润湿状态转变所需的电压均随着SDS浓度的增加而减小。当水溶液中SDS的浓度固定时,沿垂直于凹槽方向的启动电压随着固相分数的减小而减小,沿平行于凹槽方向的启动电压随着固相分数的减小而增大,而饱和电压均随着固相分数的减小而减小。结论添加十二烷基硫酸钠可以有效降低SDS水溶液液滴电润湿的启动电压和电润湿过程中水溶液液滴在微凹槽PDMS表面润湿状态转变所需的电压,使得SDS水溶液液滴在微凹槽阵列PDMS表面的电润湿行为发生了改变。Electrowetting on dielectric(EWOD)has found wide applications in micro-/nano-fluidics for its precise and accurate manipulation of minor droplets.Micro-grooved non-wetting surfaces exhibit great anisotropy in surface wettability and have been used as surfaces for directional transport of liquid.The work aims to study the electrowetting characteristics of aqueous sodium dodecyl sulfate(SDS)agueous droplets on micro-grooved polydimethylsiloxane(PDMS)surfaces,which were obtained by the peeling-off method.The solid fraction of micro-grooved PDMS surfaces was 0.50,0.33 and 0.20,respectively.SDS concentration was fixed at 0,0.41,0.82,1.23 and 1.62 mmol/L,respectively.Firstly,wettability of SDS aqueous droplets containing 1 mmol/L KCl on micro-grooved PDMS surfaces without the application of a direct current(DC)electric field was measured.It was found that all droplets were at the Cassie-Baxter wetting state,micro-grooved surfaces exhibited a strong anisotropy in surface wettability,and the apparent,advancing and receding contact angles were all larger in the transverse direction than the corresponding values in the longitudinal direction.Secondly,eletrowetting of aqueous SDS droplets containing 1 mmol/L KCl on micro-grooved PDMS surfaces was experimentally studied by varying SDS concentration and surface roughness of the substrate.Platinum wire was inserted into the mixture droplet as an electrode and micro-grooved PDMS surfaces were placed on the conducting layer of ITO glass.DC electric field was applied to the system at the increase speed of 20 V/s and droplet shape analyzer DSA30 was adjusted as soon as possible to record the profile of sessile droplets at the speed of 1 frame per second.The non-wetting surface of micro-grooved array showed strong wettability anisotropy.Compared with the apparent contact angle(110°≤θe≤141°),advancing angle(116°≤θa≤144°)and retreating angle(99°≤θr≤137°)in the longitudinal direction,the apparent contact angle(142°≤θe≤165°),advancing angle(159°≤θa≤177

关 键 词：十二烷基硫酸钠 液滴 启动电压 饱和电压 表面粗糙度 接触角滞后 

分 类 号：O369[理学—流体力学] TB34[理学—力学]