Quantitative characterization of surface wettability by friction force

Shi, Kui; Li, Qian; Zhang, Jinhong; Li, Lijun; Yang, Biao; Hu, Shiqi; Lei, Yifeng; Liu, Ze; Liu, Sheng; Xue, Longjian

doi:10.1016/j.apsusc.2020.147788

Cited by 19 publications

(29 citation statements)

References 26 publications

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“…When the shear displacement of a liquid bridge becomes large enough to cause a moving wetting line, both the left–right contact angle difference and the lateral capillary force are maximized. , Similar results were also observed in tilted plate − or forced liquid drop sliding experiments. − In studies in which the wetting line speed was constant, the lateral adhesion force was found to be generally proportional to the contact width of the liquid ( w ), the liquid surface tension ( γ LA ), and the difference in cosines of the left and right contact angles (cos θ l – cos θ r ). ,,− In experiments in which the wetting line speed was varied, the lateral adhesion force was found to increase linearly with the wetting line speed. ,, Gao et al found such a monotonic relation was valid only if the capillary number (Ca) was >10 –5 . The linear relation between wetting line speed U and the lateral capillary force was best explained by the linear form of the notable contact line friction hypothesis, F W = Uζ = Uk B T /κ 0 λ 3 , where F W is the lateral force per unit contact line width, ζ the coefficient of wetting line friction, k B the Boltzmann constant, T the absolute temperature, κ 0 the equilibrium frequency of the random molecular displacements, and λ the microscopic distance between adsorption sites on the solid surface …”

Section: Introductionmentioning

confidence: 56%

Lateral and Normal Capillary Force Evolution of a Reciprocating Liquid Bridge

et al. 2021

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Capillary forces of a shearing liquid bridge can significantly affect the friction and adhesion of interacting surfaces, but the underlying mechanisms remain unclear. We custom built a surface force apparatus (SFA, ±2 μN) equipped with in situ optical microscopy and performed normal and lateral force measurements on a reciprocating water bridge formed between two flat plates. A modified wedge method was developed to correct the unique force measurement errors caused by the changing bridge geometry and position. The results found (1) strong linear relations among the bridge shear displacement, the cosine difference between the left and right contact angles, and the lateral adhesion force and (2) the normal adhesion force increased monotonically up to 13% as the bridge geometry approached its axisymmetric state. Quasi-static force analyses based on a newly developed decahedral model showed good agreement with the experiments and improved accuracy compared with that of cylindrical or rectangular column models previously proposed in the literature. Although limited in certain aspects, this study may (1) prove helpful to the design and analysis of liquid bridge force experiments on platforms similar to the SFA used in this study and (2) help to bridge the gap between friction and liquid bridge physics in the literature.

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Section: Introductionmentioning

confidence: 56%

Lateral and Normal Capillary Force Evolution of a Reciprocating Liquid Bridge

et al. 2021

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“…There are many more of these types of surfaces, on which water droplets show anisotropic wetting behaviors [ 8 , 9 , 10 , 11 , 12 ]. Inspired by the anisotropic surfaces found in nature, engineered surfaces with anisotropic wetting properties could contribute significantly to the fields, such as biomedicine, ship transportation, microfluidics, smart surfaces, and so on [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

“…For instance, on the surface composed of a polydimethylsiloxane (PDMS) triangular-micropillar array, with the period ranging from 40 to 50 µm, a negligible difference in the SAs (ΔSA = 3°) in opposite directions can be found [ 16 ]. Similarly, on the microstrip surfaces, with the air fraction ranging from 0.20 to 0.50, the water droplets kept sticking to the surface when the surface was turned upside down along the direction perpendicular to the microstrips [ 17 ]. In both cases, there is no difference in the SA along certain directions, even though the surface structures are distinctly different [ 16 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

“…Similarly, on the microstrip surfaces, with the air fraction ranging from 0.20 to 0.50, the water droplets kept sticking to the surface when the surface was turned upside down along the direction perpendicular to the microstrips [ 17 ]. In both cases, there is no difference in the SA along certain directions, even though the surface structures are distinctly different [ 16 , 17 ]. It clearly suggests that the SA measurement cannot reveal the structural difference of these examined surfaces and what the extent of the difference could be [ 16 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

“…In both cases, there is no difference in the SA along certain directions, even though the surface structures are distinctly different [ 16 , 17 ]. It clearly suggests that the SA measurement cannot reveal the structural difference of these examined surfaces and what the extent of the difference could be [ 16 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Anisotropic Wettability of Bioinspired Surface Characterized by Friction Force

Zhang

et al. 2022

Biomimetics

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Bioinspired surfaces with special wettabilities attract increasing attention due to their extensive applications in many fields. However, the characterizations of surface wettability by contact angle (CA) and sliding angle (SA) have clear drawbacks. Here, by using an array of triangular micropillars (ATM) prepared by soft lithography, the merits of measuring the friction force of a water droplet on ATM over measurements of CA and SA in characterizing the surface wettability are demonstrated. The CA and SA measurements show ignorable differences in the wettabilities of ATM in opposite directions (1.13%) and that with different periodic parameters under the elongation ranging from 0 to 70%. In contrast, the friction measurement reveals a difference of > 10% in opposite directions. Moreover, the friction force shows a strong dependence on the periodic parameters which is regulated by mechanical stretching. Increasing the elongation from 0 to 50% increases the static and kinetic friction force up to 23.0% and 22.9%, respectively. Moreover, the stick-slip pattern during kinetic friction can reveal the periodic features of the measured surface. The friction force measurement is a sensitive technique that could find applications in the characterization of surface wettabilities.

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Analysis of water droplet motion on hydrophobic surfaces with different microstructures

Zhang,

Feng,

et al. 2024

J of Applied Polymer Sci

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The influence of material surface microstructure on interface properties is crucial for the preparation and development of special functional materials. In this paper, polydimethylsiloxane‐based superhydrophobic surfaces of varying roughness and surface energy are prepared using the template method and a spraying technique, and the effect of surface microstructure on lateral friction is studied using a lateral friction detection system. The experimental results indicate that as the surface roughness of a sample decreases, it is observed that the water droplets transition from a Cassie state to a Wenzel state. When the roughness changes from 4.619 μm, reduce to 3.512 μm, the maximum static friction force increases from 33.59 μN increased to 51.52 μN. The lateral sliding friction force ranges from 15.87 ± 1.9 μN increases to 40.91 ± 1.2 μN. For a given surface roughness, when the surface energy is reduced, the water droplets on the surface can be seen to transition from a Wenzel state to a Cassie state, the maximum static friction force increases from 19.32 μN dropped to 9.23 μN, and the lateral sliding friction force increases from 15.26 ± 1.6 μN dropped to 3.47 ± 2.1 μN. However, this behavior is distinct from that observed when changing the roughness of the sample. Studying the influence of the surface microstructure on the lateral friction force observed at a solid–liquid interface can provide important insights into novel geometries that may be used in new, advanced functional surfaces.

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Quantitative characterization of surface wettability by friction force

Cited by 19 publications

References 26 publications

Lateral and Normal Capillary Force Evolution of a Reciprocating Liquid Bridge

Lateral and Normal Capillary Force Evolution of a Reciprocating Liquid Bridge

Anisotropic Wettability of Bioinspired Surface Characterized by Friction Force

Analysis of water droplet motion on hydrophobic surfaces with different microstructures

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