Modifying surface forces through control of surface potentials.
نویسندگان
چکیده
Combining direct surface force measurements with in situ regulation of surface potential provides an exceptional opportunity for investigating and manipulating interfacial phenomena. Recently, we studied the interaction between gold and mica surfaces in water with no added salt, while controlling the metal potential, and found that the surface charge at the metal may vary, and possibly even change its sign, as it progressively approaches the (constant-charge) mica surface [Langmuir, 2015, 31(47), 12845-12849]. Such a variation was found to directly affect the nature of the contact and adhesion between them due to exclusion of all mobile counterions from the intersurface gap. In this work, we extend this to examine the potential-dependent response of the adhesion and interaction between gold and mica to externally applied voltages and in electrolyte solution. Using a surface force balance (SFB) combined with a three-electrode electrochemical cell, we measured the normal interaction between gold and mica under surface potential regulation, revealing three interaction regimes - pure attraction, non-monotonic interaction from electrostatic repulsion to attraction (owing to charge inversion) and pure repulsion. Accordingly, the adhesion energy between the surfaces was found to vary both in no added salt water and, more strongly, in electrolyte solution. We justify this potential-dependent variation of adhesion energy in terms of the interplay between electrostatic energy and van der Waals (vdW) interaction at contact, and attribute the difference between the two cases to the weaker vdW interaction in electrolyte solution. Finally, we showed that through abruptly altering the gold surface potential from negative to positive and vice versa, the adhesion between gold and mica can be reversibly switched on and off. We surmise that the process of bringing the surface into contact is associated with the formation of a strong electric field O (108 V m-1) in the intersurface gap.
منابع مشابه
Polyvinylidene Fluoride Hollow Fiber Membrane Contactor Incorporating Surface Modifying Macromolecule for Carbon Dioxide Stripping from Water
Porous surface modified polyvinylidene ïuoride (PVDF) hollow fiber membranes are fabricated through a dry-wet phased inversion process. Surface modifying macromolecules (SMM) (1 wt. %) are used as additives in the spinning dope. The performance of the surface modified membrane in contactor application for CO2 stripping from water is assessed through the fabricated gas–liquid membrane contacto...
متن کاملNonlocal Piezomagnetoelasticity Theory for Buckling Analysis of Piezoelectric/Magnetostrictive Nanobeams Including Surface Effects
This paper presents the surface piezomagnetoelasticity theory for size-dependent buckling analysis of an embedded piezoelectric/magnetostrictive nanobeam (PMNB). It is assumed that the subjected forces from the surrounding medium contain both normal and shear components. Therefore, the surrounded elastic foundation is modeled by Pasternak foundation. The nonlocal piezomagnetoelasticity theory i...
متن کاملstudy of contribution of hydrodynamics and surface forces to controlled particle deposition
متن کامل
Non-Singular Terminal Sliding Mode Control of a Nonholonomic Wheeled Mobile Robots Using Fuzzy Based Tyre Force Estimator
This paper, proposes a methodology to implement a suitable nonsingular terminal sliding mode controller associated with the output feedback control to achieve a successful trajectory tracking of a non-holonomic wheeled mobile robot in presence of longitudinal and lateral slip accompanied. This implementation offers a relatively faster and high precision tracking performance. We investigate this...
متن کاملControl of adhesion and surface forces via potential-dependent adsorption of pyridine.
The orientation and extent of adsorption of pyridine on a gold electrode is known to depend on applied potential and is well characterized. By use of the electrochemical surface forces apparatus, we measured the potential dependence of the double-layer interactions and adhesive forces between a gold electrode and a mica surface for different pyridine concentrations. We observed that, unlike mic...
متن کاملCoadsorption of Dioxygen and Carbon Monoxide on a Mg(100) Surface
The activation of carbon monoxide by oxygen on Mg(100) surface has been investigated by X-ray photoelectron spectroscopy (XPS). Carbon monoxide is only weakly adsorbed (dispersion-type forces) on a magnesium surface. The XPS result has shown that the dissociation of carbon monoxide leading to the formation of a metastable surface carbonate species occurs through the participation of an oxyg...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Faraday discussions
دوره 199 شماره
صفحات -
تاریخ انتشار 2017