Correcting for Surface Roughness:  Advancing and Receding Contact Angles

Langmuir ◽  
2002 ◽  
Vol 18 (16) ◽  
pp. 6465-6467 ◽  
Author(s):  
Masahide Taniguchi ◽  
Georges Belfort
Keyword(s):  
Surface Roughness ◽  
Contact Angles ◽  
Receding Contact

Facile manipulation of receding contact angles of a substrate by roughening and fluorination

2015 ◽  
Vol 355 ◽  
pp. 127-132 ◽  
Author(s):  
Yueh-Feng Li ◽  
Cyuan-Jhang Wu ◽  
Yu-Jane Sheng ◽  
Heng-Kwong Tsao
Keyword(s):  
Contact Angles ◽  
Receding Contact

Influence of surface roughness on the wetting angle

1995 ◽  
Vol 10 (8) ◽  
pp. 1984-1992 ◽  
Author(s):  
X.B. Zhou ◽  
J.Th.M. De Hosson
Keyword(s):  
Surface Roughness ◽  
Gaussian Distribution ◽  
Rough Surfaces ◽  
Contact Angles ◽  
Wetting Angle ◽  
Experimental Results ◽  
Solid Surfaces ◽  
Roughness Measurements

A this paper the influence of surface roughness on contact angles in the system of liquid Al wetting solid surfaces of Al2O3 has been studied. It was observed that contact angles of liquid Al vary significantly on different rough surfaces of Al2O3. A model is proposed to correlate contact angles with conventional roughness measurements and wavelengths by assuming a cosine profile of rough grooves with a Gaussian distribution of amplitudes. In comparison with the experimental results, the model provides a good estimate for describing the influence of surface roughness on contact angles of liquid Al on Al2O3.

The Surface Modification with Fluorocarbon Thin Films for the Prevention of Stiction in Mems

1998 ◽  
Vol 518 ◽  
Author(s):  
Sang-Ho Lee ◽  
Myong-Jong Kwon ◽  
Jin-Goo Park ◽  
Yong-Kweon Kim ◽  
Hyung-Jae Shin
Keyword(s):  
Contact Angle ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Fluorocarbon Films ◽  
Perfluorodecanoic Acid ◽  
Large Hysteresis ◽  
Static Contact ◽  
Receding Contact ◽  
Highly Hydrophobic ◽  
Receding Contact Angle

AbstractHighly hydrophobic fluorocarbon films were prepared by the vapor phase (VP) deposition method in a vacuum chamber using both liquid (3M's FC40, FC722) and solid sources (perfluorodecanoic acid (CF3(CF2)8COOH), perfluorododecane (C12F26)) on Al, Si and oxide coated wafers. The highest static contact angles of water were measured on films deposited on aluminum substrate. But relatively lower contact angles were obtained on the films on Si and oxide wafers. The advancing and receding contact angle analysis using a captive drop method showed a large contact angle hysteresis (ΔH) on the VP deposited fluorocarbon films. AFM study showed poor film coverage on the surface with large hysteresis. FTIR-ATR analysis positively revealed the stretching band of CF2 groups on the VP deposited substrates. The thermal stability of films was measured at 150°C in air and nitrogen atmospheres as a function of time. The rapid decrease of contact angles was observed on VP deposited FC and PFDA films in air. However, no decrease of contact angle on them was observed in N2.

Effects of surfactants and polymers on advancing and receding contact angles

1986 ◽  
Vol 17 (4) ◽  
pp. 325-342 ◽  
Author(s):  
Barbara A. Johnson ◽  
Jörg Kreuter ◽  
George Zografi
Keyword(s):  
Contact Angles ◽  
Receding Contact

scholarly journals Which Is the Motion State of a Droplet on an Inclined Hydrophilic Rough Surface in Gravity: Pinned or Sliding?

2021 ◽  
Vol 11 (9) ◽  
pp. 3734
Author(s):  
Jian Dong ◽  
Youhai Guo ◽  
Long Jiao ◽  
Chao Si ◽  
Yinbo Bian ◽  
...  
Keyword(s):  
Rough Surface ◽  
Contact Angle Hysteresis ◽  
Minimum Energy ◽  
Contact Angles ◽  
Microfluidic Chips ◽  
Motion State ◽  
Receding Contact ◽  
Novel Design ◽  
Minimum Energy Dissipation ◽  
Good Agreement

The motion state of a droplet on an inclined, hydrophilic rough surface in gravity, pinned or sliding, is governed by the balance between the driving and the pinned forces. It can be judged by the droplet’s shape on the inclined hydrophilic rough surface and the droplet’s contact angle hysteresis. In this paper, we used the minimum energy theory, the minimum energy dissipation theory, and the nonlinear numerical optimization algorithm to establish Models 1–3 to calculate out the advancing/receding contact angles (θa/θr), the initial front/rear contact angles (θ1−0/θ2−0) and the dynamic front/rear contact angles (θ1−*/θ2−*) for a droplet on a rough surface. Also, we predicted the motion state of the droplet on an inclined hydrophilic rough surface in gravity by comparing θ1−0(θ2−0) and θ1−*(θ2−*) with θa(θr). Experiments were done to verify the predictions. They showed that the predictions were in good agreement with the experimental results. These models are promising as novel design approaches of hydrophilic functional rough surfaces, which are frequently applied to manipulate droplets in microfluidic chips.

Surface Topography Induced Ultrahydrophobic Behavior: Effect of Three-Phase Contact Line Topology

2006 ◽  
Author(s):  
Neeharika Anantharaju ◽  
Mahesh Panchagnula ◽  
Wayne Kimsey ◽  
Sudhakar Neti ◽  
Svetlana Tatic-Lucic
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Anomalous Behavior ◽  
Contact Angles ◽  
Wet Etching ◽  
Surface Geometry ◽  
Wetting Behavior ◽  
Void Fractions ◽  
Three Phase ◽  
Receding Contact

The wettability of silicon surface hydrophobized using silanization reagents was studied. The advancing and receding contact angles were measured with the captive needle approach. In this approach, a drop under study was held on the hydrophobized surface with a fine needle immersed in it. The asymptotic advancing and receding angles were obtained by incrementally increasing the volume added and removed, respectively, until no change in angles was observed. The values were compared with the previously published results. Further, the wetting behavior of water droplets on periodically structured hydrophobic surfaces was investigated. The surfaces were prepared with the wet etching process and contain posts and holes of different sizes and void fractions. The surface geometry brought up a scope to study the Wenzel (filling of surface grooves) and Cassie (non filling of the surface grooves) theories and effects of surface geometry and roughness on the contact angle. Experimental data point to an anomalous behavior where the data does not obey either Wenzel or Cassie type phenomenology. This behavior is explained by an understanding of the contact line topography. The effect of contact line topography on the contact angle was thus parametrically studied. It was also inferred that, the contact angle increased with the increase in void fraction. The observations may serve as guidelines in designing surfaces with the desired wetting behavior.

scholarly journals Sessile droplets on deformable substrates

2018 ◽  
Author(s):  
Gulraiz Ahmed ◽  
Nektaria Koursari ◽  
Anna Trybala ◽  
Victor M. Starov
Keyword(s):  
Liquid Droplet ◽  
Contact Angles ◽  
Surface Forces ◽  
Interfacial Behavior ◽  
Equilibrium Conditions ◽  
The Past ◽  
Technological Advances ◽  
Three Phase ◽  
Significant Interest ◽  
Receding Contact

Wetting of deformable substrates has gained significant interest over the past decade due to its extensive applications and uses. This interest has developed due to technological advances which are able to capture interfacial behavior taking place when a liquid droplet is placed on a deformable substrate. Researchers have developed different theories to explain processes taking place in the process of wetting of deformable/soft substrates. For the scope of this review, we will consider the fluid to be Newtonian, partially wetting, and surface forces are incorporated with the help of disjoining/conjoining pressure acting in the vicinity of the apparent, three-phase contact line. The following subjects are briefly reviewed: (i) Equilibrium of droplets on soft substrates. It is shown that properties of the disjoining/conjoining pressure isotherm and properties of the deformable substrate determine both the shape of the liquid droplet and deformation of the substrate; (ii) Equilibrium conditions of droplets on deformable substrates. It is shown that for a droplet to be at equilibrium on a deformable substrate under consideration, Jacobi’s sufficient condition is satisfied; (iii) Hysteresis of contact angle of sessile droplets on deformable substrates. It is shown that as the elasticity of the deformable substrate is increased, both advancing and receding contact angles are reduced.

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