Hemispherical nanobubbles reduce interfacial slippage in simple liquids.
نویسندگان
چکیده
Using an electrochemical quartz crystal microbalance (EQCM), we have produced bubbles of nanoscopic size at the front electrode of an acoustic shear wave resonator. Nanobubbles are usually expected to increase the resonance frequency because they have a low density and, also, because a liquid slides easily at a liquid-air interface. However, the bubble-induced frequency shift in many cases was negative, which implies positive hydrodynamic thickness and reduced slippage. The explanation is based on Laplace pressure. Due to the bubbles' inherent stiffness, the space in-between neighboring bubbles may turn into an assembly of pockets which move with the underlying substrate in the same way as a solid film. If, first, the bubbles are so small that the Laplace pressure can overcome the viscous drag, and, second, the contact angle is in the range of 90°, the latter effect dominates. This interpretation was corroborated by a calculation using the finite element method (FEM). The argument as such is not limited to acoustic shear waves: hemispherical nanobubbles increase the surface drag in stationary flows in the same way.
منابع مشابه
Low-friction flows of liquid at nanopatterned interfaces.
With the important development of microfluidic systems, miniaturization of flow devices has become a real challenge. Microchannels, however, are characterized by a large surface-to-volume ratio, so that surface properties strongly affect flow resistance in submicrometre devices. We present here results showing that the concerted effect of wetting properties and surface roughness may considerabl...
متن کاملA predictive framework for the design and fabrication of icephobic polymers
Ice accretion remains a costly, hazardous concern worldwide. Icephobic coatings reduce the adhesion between ice and a surface. However, only a handful of the icephobic systems reported to date reduce the ice adhesion sufficiently for the facile and passive removal of ice, such as under its own weight or by mild winds. Most of these icephobic surfaces have relied on sacrificial lubricants, which...
متن کاملEffect of surface modification on interfacial nanobubble morphology and contact line tension.
Past research has confirmed the existence of surface nanobubbles on various hydrophobic substrates (static contact angle >90°) when imaged in air-equilibrated water. Additionally, the use of solvent exchange techniques (based on the difference in saturation levels of air in various solvents) also introduced surface nanobubbles on hydrophilic substrates (static contact angle <90°). In this work,...
متن کاملNanobubble “Snapshot” on a Polymer Matrix
The nanometer size of gaseous nanobubbles formed in liquids and their physical properties impose limitations to the selection of imaging techniques. The prospectiveex situ imaging method is developed to utilize imprints, which nanobubbles form on immersed polymer surfaces. Polymer nanopattern represent a “snap-shot” record of the nanobubble existence, which can be imagedex post byex situ AFM. T...
متن کاملMolecular dynamics study on helium nanobubbles in water.
Interfacial properties of helium nanobubbles in water at normal conditions have been investigated using large-scale molecular dynamics simulations for systems including over one million atoms. The surface tension of a helium nanobubble is a convex function with respect to the bubble radius, and is estimated to vanish at a critical radius of approximately 1 nm.
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:
- Physical chemistry chemical physics : PCCP
دوره 13 40 شماره
صفحات -
تاریخ انتشار 2011