Electrokinetics at Aqueous Interfaces without Mobile Charges

详细信息    查看全文

• 作者：Douwe Jan Bonthuis ; Dominik Horinek ; Lydric Bocquet ; Roland R. Netz
• 刊名：Langmuir
• 出版年：2010
• 出版时间：August 3, 2010
• 年：2010
• 卷：26
• 期：15
• 页码：12614-12625
• 全文大小：1310K
• 年卷期：v.26,no.15(August 3, 2010)
• ISSN：1520-5827

文摘

We theoretically consider the possibility of using electric fields in aqueous channels of cylindrical and planar geometry to induce transport in the absence of mobile ionic charges. Using the Navier−Stokes equation, generalized to include the effects of water spinning, dipole orientation and relaxation, we show analytically that pumping of a dipolar liquid through an uncharged hydrophobic channel can be achieved by injecting torque into the liquid, based on the coupling between molecular spinning and fluid vorticity. This is possible using rotating electric fields and suitably chosen interfacial boundary conditions or transiently by suddenly switching on a homogeneous electric field. A static electric field, however, does not induce a steady state flow in channels, irrespective of the geometry. Using molecular dynamics (MD) simulations, we confirm that static fields do not lead to any pumping, in contrast to earlier publications. The pumping observed in MD simulations of carbon nanotubes and oil droplets in a static electric field is tracked down to an imprudent implementation of Lennard-Jones interaction truncation schemes.