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

Abstract

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.