Electrical Perturbations of Ultrathin Bilayers: Role of Ionic Conductive Layer

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• 作者：Hadi Nazaripoor ; Charles R. Koch ; Subir Bhattacharjee
• 刊名：Langmuir
• 出版年：2014
• 出版时间：December 16, 2014
• 年：2014
• 卷：30
• 期：49
• 页码：14734-14744
• 全文大小：742K
• ISSN：1520-5827

文摘

The effect of electrostatic force on the dynamics, morphological evolution, and drainage time of ultrathin liquid bilayers (<100 nm) are investigated for perfect dielectric鈥損erfect dielectric (PD鈥揚D) and ionic liquid鈥損erfect dielectric (IL鈥揚D) bilayers. The weakly nonlinear 鈥渢hin film鈥?equation is solved numerically to obtain spatiotemporal evolution of the liquid鈥搇iquid interface responses to transverse electric field. In order to predict the electrostatic component of conjoining/disjoining pressure acting on the interface for IL鈥揚D bilayers, an analytical model is developed using the nonlinear Poisson-Boltzmann equation. It is found that IL鈥揚D bilayers with electric permittivity ratio of layers (lower to top), 蔚_r, greater than one remain stable under an applied electric field. An extensive numerical study is carried out to generate a map based on 蔚_r and the initial mean thickness of the lower layer. This map is used to predict the formation of various structures on PD鈥揚D bilayer interface and provides a baseline for unstable IL鈥揚D bilayers. The use of an ionic liquid (IL) layer is found to reduce the size of the structures, but results in polydispersed and disordered pillars spread over the domain. The numerical predictions follow similar trend of experimental observation of Lau and Russel. (Lau, C. Y.; Russel, W. B. Fundamental Limitations on Ordered Electrohydrodynamic Patterning; Macromolecules 2011, 44, 7746鈥?751).