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Wetting on flexible hydrophilic pillar-arrays.

Yuan Q, Zhao YP - Sci Rep (2013)

Bottom Line: For the first time, the combined effect of the surface topology, the intrinsic wettability and the elasticity of a solid on the wetting process is taken into consideration.Scaling analysis is performed based on molecular kinetic theory and validated by our simulations.Our results may expand our knowledge of wetting on pillars and assisting the future design of active control of wetting in practical applications.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, People's Republic of China.

ABSTRACT
Dynamic wetting on the flexible hydrophilic pillar-arrays is studied using large scale molecular dynamics simulations. For the first time, the combined effect of the surface topology, the intrinsic wettability and the elasticity of a solid on the wetting process is taken into consideration. The direction-dependent dynamics of both liquid and pillars, especially at the moving contact line (MCL), is revealed at atomic level. The flexible pillars accelerate the liquid when the liquid approaches, and pin the liquid when the liquid passes. The liquid deforms the pillars, resulting energy dissipation at the MCL. Scaling analysis is performed based on molecular kinetic theory and validated by our simulations. Our results may expand our knowledge of wetting on pillars and assisting the future design of active control of wetting in practical applications.

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(a) Snapshots of the wetting of a droplet on a smooth hydrophilic surface.(b) Evolution of droplet radius R in polar coordinate. The origin O is put on the centre of the droplet. The radial and the angular coordinate represent time evolution and the direction, respectively. The colour represents the spreading distance labeled by the below colour legend. The total time is 2.5 ns. (c) Evolution of R with respect to t at 45° labeled in (b).
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f5: (a) Snapshots of the wetting of a droplet on a smooth hydrophilic surface.(b) Evolution of droplet radius R in polar coordinate. The origin O is put on the centre of the droplet. The radial and the angular coordinate represent time evolution and the direction, respectively. The colour represents the spreading distance labeled by the below colour legend. The total time is 2.5 ns. (c) Evolution of R with respect to t at 45° labeled in (b).

Mentions: Fig. 5(a) shows a droplet propagating on a smooth hydrophilic surface. Fig. 5(b) shows the evolution of droplet radius in polar coordinate, in which the radial, the angular coordinate and the colour represent the time evolution, the direction and the spreading distance labeled by the below colour legend, respectively. In Fig. 5(b), point A (1.5 ns, 20°, orange) represents the liquid at 20° advances about 40–45 Å in 1.5 ns. Line at 45° in Fig. 5(b) represents spreading radius of liquid at 45° with respect to time shown in Fig. 5(c), which obeys a scaling law of R ~ t1/7. The spreading of droplet on a smooth surface is nearly isotropic, i.e. independent of direction.


Wetting on flexible hydrophilic pillar-arrays.

Yuan Q, Zhao YP - Sci Rep (2013)

(a) Snapshots of the wetting of a droplet on a smooth hydrophilic surface.(b) Evolution of droplet radius R in polar coordinate. The origin O is put on the centre of the droplet. The radial and the angular coordinate represent time evolution and the direction, respectively. The colour represents the spreading distance labeled by the below colour legend. The total time is 2.5 ns. (c) Evolution of R with respect to t at 45° labeled in (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3672886&req=5

f5: (a) Snapshots of the wetting of a droplet on a smooth hydrophilic surface.(b) Evolution of droplet radius R in polar coordinate. The origin O is put on the centre of the droplet. The radial and the angular coordinate represent time evolution and the direction, respectively. The colour represents the spreading distance labeled by the below colour legend. The total time is 2.5 ns. (c) Evolution of R with respect to t at 45° labeled in (b).
Mentions: Fig. 5(a) shows a droplet propagating on a smooth hydrophilic surface. Fig. 5(b) shows the evolution of droplet radius in polar coordinate, in which the radial, the angular coordinate and the colour represent the time evolution, the direction and the spreading distance labeled by the below colour legend, respectively. In Fig. 5(b), point A (1.5 ns, 20°, orange) represents the liquid at 20° advances about 40–45 Å in 1.5 ns. Line at 45° in Fig. 5(b) represents spreading radius of liquid at 45° with respect to time shown in Fig. 5(c), which obeys a scaling law of R ~ t1/7. The spreading of droplet on a smooth surface is nearly isotropic, i.e. independent of direction.

Bottom Line: For the first time, the combined effect of the surface topology, the intrinsic wettability and the elasticity of a solid on the wetting process is taken into consideration.Scaling analysis is performed based on molecular kinetic theory and validated by our simulations.Our results may expand our knowledge of wetting on pillars and assisting the future design of active control of wetting in practical applications.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, People's Republic of China.

ABSTRACT
Dynamic wetting on the flexible hydrophilic pillar-arrays is studied using large scale molecular dynamics simulations. For the first time, the combined effect of the surface topology, the intrinsic wettability and the elasticity of a solid on the wetting process is taken into consideration. The direction-dependent dynamics of both liquid and pillars, especially at the moving contact line (MCL), is revealed at atomic level. The flexible pillars accelerate the liquid when the liquid approaches, and pin the liquid when the liquid passes. The liquid deforms the pillars, resulting energy dissipation at the MCL. Scaling analysis is performed based on molecular kinetic theory and validated by our simulations. Our results may expand our knowledge of wetting on pillars and assisting the future design of active control of wetting in practical applications.

Show MeSH