电场作用下5CB液晶分子的近壁面层黏弹性的QCM研究  

Investigation on viscoelastic behaviors of near-interface 5CB liquid crystal under electric field with quartz crystal microbalance

作　　者：熊毅[1] 张向军[1] 张晓昊[1] 温诗铸[1] 

机构地区：[1]清华大学摩擦学国家重点实验室,北京100084

出　　处：《物理学报》2010年第11期7998-8004,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:50975154;50730007);国家重点基础研究发展计划(批准号:2007CB607604);国家自然科学基金委创新研究群体(批准号:50721004)~~

摘　　要：利用石英晶体微天平(quartz crystal microbalance,QCM)研究了电场对5CB液晶分子的近壁面层黏弹性的影响.对QCM结果的分析发现,电场作用对液晶的黏度影响分为两部分,通过建立含吸附膜的双层膜模型,分析了QCM的两部分结果,发现电场对近壁面吸附层及体相层的影响是不同的.根据QCM的双层膜模型,对近壁面层液晶分子的黏弹性及膜厚进行了定量的分析计算,结果表明5CB在石英晶体上电极附近有一层约100nm厚的近壁面吸附层,其复剪切黏度随电场强度的增加而减小,这与5CB液晶的体相黏度变化规律相反.The influence of electric field on near-interface 4-pentyl-4′-cyanobiphenyl（5CB） liquid crystal （LC） is investigated with quartz crystal microbalance （QCM）.The results of QCM show that the process of frequency shifting with electric field,which reflects the viscoelasticity change of 5CB,can be divided into two parts.Then the two-layer model of 5CB is proposed to illuminate the results of QCM,thereby indicating that the effect of electric field on near-interface layer is different from on bulk layer.Quantitative analysis is carried out with two-layer model of QCM,which indicates that there is a near-interface layer of about 100nm,adsorbed on the upper electrode of quartz crystal.The complex shear viscosity of the near-interface layer decreases with electric field strength increasing,which is opposite to the rule of bulk viscosity of 5CB.

关 键 词：5CB液晶 石英晶体微天平 近壁面 黏弹性 

分 类 号：O753.2[理学—晶体学]