Surfactant Self-Assemblies Near Contact Lines and their Effect on Wetting by Surfactant Solutions

1994 ◽  
Vol 366 ◽  
Author(s):  
B. Frank ◽  
S. Garoff
Keyword(s):  
Pattern Formation ◽  
Contact Line ◽  
Self Assembly ◽  
Surface Interactions ◽  
Contact Lines ◽  
Dynamic Wetting ◽  
Wetting Behavior ◽  
Wetting Properties ◽  
Surfactant Solutions ◽  
Solid Liquid

ABSTRACTSurfactant self-assembly at the liquid-vapor, solid-liquid, and solid-vapor interfaces controls the wetting behavior of advancing surfactant solutions. While different surfactants exhibit different static and dynamic wetting properties, we show that these behaviors can be understood through an examination of microscopic structures driven by surfactant-surface interactions. We examine surfactant solutions exhibiting complete and partial static wetting as well as spreading by dendritic pattern formation and unsteady, stick-jump behavior. In each case, the observed behavior is related to the structure of the surfactant assemblies in the vicinity of the contact line.

Dynamic wetting failure in surfactant solutions

2016 ◽  
Vol 789 ◽  
pp. 285-309 ◽  
Author(s):  
Chen-Yu Liu ◽  
Eric Vandre ◽  
Marcio S. Carvalho ◽  
Satish Kumar
Keyword(s):  
Contact Line ◽  
Rectangular Channel ◽  
Air Entrainment ◽  
Steady State Solution ◽  
Contact Angles ◽  
Pressure Gradients ◽  
Computationally Efficient ◽  
Dynamic Wetting ◽  
Surfactant Solutions ◽  
Limit Points

The influence of insoluble surfactants on dynamic wetting failure during displacement of Newtonian fluids in a rectangular channel is studied in this work. A hydrodynamic model for steady Stokes flows of dilute surfactant solutions is developed and evaluated using three approaches: (i) a one-dimensional (1D) lubrication-type approach, (ii) a novel hybrid of a 1D description of the receding phase and a 2D description of the advancing phase, and (iii) an asymptotic theory of Cox (J. Fluid Mech., vol. 168, 1986b, pp. 195–220). Steady-state solution families in the form of macroscopic contact angles as a function of the capillary number are determined and limit points are identified. When air is the receding fluid, Marangoni stresses are found to increase the receding-phase pressure gradients near the contact line by thinning the air film without significantly changing the capillary-pressure gradients there. As a consequence, the limit points shift to lower capillary numbers and the onset of wetting failure is promoted. The model predictions are then used to interpret decades-old experimental observations concerning the influence of surfactants on air entrainment (Burley & Kennedy, Chem. Engng Sci., vol. 31, 1976, pp. 901–911). In addition to being a computationally efficient alternative for the rectangular geometries considered here, the hybrid modelling approach developed in this paper could also be applied to more complicated geometries where a thin air layer is present near a contact line.

801 Dynamic Wetting Behavior of a Contact Line Passing over Wall Defects with Different Wettability

2014 ◽  
Vol 2014.89 (0) ◽  
pp. _8-1_
Author(s):  
Shota IWAHATA ◽  
Kenji KATOH ◽  
Tatsuro WAKIMOTO ◽  
Takahiro ITO ◽  
Yasufumi YAMAMOTO
Keyword(s):  
Contact Line ◽  
Dynamic Wetting ◽  
Wetting Behavior ◽  
Line Passing

Modelling the Influence of Wetting Properties on the Solid Liquid Impact

2008 ◽  
Author(s):  
Minh Do-Quang ◽  
Gustav Amberg
Keyword(s):  
Liquid Surface ◽  
Solid Sphere ◽  
Navier Stokes ◽  
Dynamic Wetting ◽  
Wetting Properties ◽  
Liquid Impact ◽  
Free Air ◽  
Small Change ◽  
Solid Liquid ◽  
The Impact

The impact of a solid object on a free liquid surface is quite complex. This problem has challenged researchers for centuries and remains of interest today. Recently Duez et al. [1] published experimental results on the splash when a solid sphere enters a liquid. Surprisingly, a small change in the surface chemistry of the object can turn a big splash into an inconspicuous disappearance and vice versa. We study this problem by solving the Navier-Stokes together with the Cahn-Hilliard equations, [2, 3], which allows us to simulate the motion of a free air-water surface in detail, in the presence of surface tension and dynamic wetting. Quantitative computational modeling of dynamic wetting is difficult in itself, but here the use of this tool allows us to study in detail how the wetting properties determine whether a splash appears or not. Our simulated results are compared with the experiments of Duez et al.

scholarly journals MATERIALI CON BAGNABILITÀ CONTROLLATA. UN’ISPIRAZIONE DALLA NATURA

2020 ◽  
Author(s):  
Silvia Ardizzone ◽  
Daniela Meroni
Keyword(s):  
Cultural Heritage ◽  
Liquid Interface ◽  
Solid Surfaces ◽  
Hydrophilic Surface ◽  
Wetting Behavior ◽  
Wetting Properties ◽  
Cohesive Forces ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Adhesive Forces

The wettability of solid surfaces is the result of the balance between adhesive and cohesive forces. When adhesive forces at the solid/liquid interface prevail over the cohesive forces in the liquid, the drops will spread over the solid leading to a good wetting as in the case of water over an hydrophilic surface. When instead the adhesive forces are weak, the liquid will not wet the surface remaining in droplets, as water on a polymer. Natural materials exhibit tailored wetting behavior: for instance, certain leaves and insects present superhydrophobic properties. By mimicking what nature creates in an exemplary way, the wetting properties of systems can be tailored experimentally to obtain materials with great applicative impact. The possible applications of such phenomena are very numerous and span from biomaterials to antistain materials, from antifog surfaces to systems for the protection of cultural heritage.

scholarly journals Superhydrophobicity and Contact-Line Issues

MRS Bulletin ◽  
2008 ◽  
Vol 33 (8) ◽  
pp. 747-751 ◽  
Author(s):  
Lichao Gao ◽  
Alexander Y. Fadeev ◽  
Thomas J. McCarthy
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Contact Angle Hysteresis ◽  
Water Repellency ◽  
Contact Angles ◽  
Single Step ◽  
Contact Lines ◽  
Lotus Effect ◽  
Three Phase ◽  
Solid Liquid

AbstractThe wettability of several superhydrophobic surfaces that were prepared recently by simple, mostly single-step methods is described and compared with the wettability of surfaces that are less hydrophobic. We explain why two length scales of topography can be important for controlling the hydrophobicity of some surfaces (the lotus effect). Contact-angle hysteresis (difference between the advancing, θA, and receding, θR, contact angles) is discussed and explained, particularly with regard to its contribution to water repellency. Perfect hydrophobicity (θA/θR = 180°/180°) and a method for distinguishing perfectly hydrophobic surfaces from those that are almost perfectly hydrophobic are described and discussed. The Wenzel and Cassie theories, both of which involve analysis of interfacial (solid/liquid) areas and not contact lines, are criticized. Each of these related topics is addressed from the perspective of the three-phase (solid/liquid/vapor) contact line and its dynamics. The energy barriers for movement of the three-phase contact line from one metastable state to another control contact-angle hysteresis and, thus, water repellency.

Dynamic wetting behavior of a triple-phase contact line in several experimental systems

2015 ◽  
Vol 60 ◽  
pp. 354-360 ◽  
Author(s):  
Kenji Katoh ◽  
Tatsuro Wakimoto ◽  
Yasufumi Yamamoto ◽  
Takahiro Ito
Keyword(s):  
Contact Line ◽  
Phase Contact ◽  
Dynamic Wetting ◽  
Wetting Behavior ◽  
Experimental Systems

116 Dynamic Wetting Behavior of Two Dimension and Axi-Symmetric Contact Lines

2012 ◽  
Vol 2012.87 (0) ◽  
pp. _1-41_
Author(s):  
Masahiro SUMITANI ◽  
Shuhei TAGUCHI ◽  
Kenji KATOH ◽  
Tatsuro WAKIMOTO
Keyword(s):  
Contact Lines ◽  
Dynamic Wetting ◽  
Wetting Behavior ◽  
Two Dimension
Sign in / Sign up

Export Citation Format

Share Document