Capillary Pressure and Contact Line Force on a Soft Solid

Abstract

The surface free energy, or surface tension, of a liquid interface gives rise to a pressure jump when the interface is curved. Here we show that a similar capillary pressure arises at the interface of soft solids. We present experimental evidence that immersion of a thin elastomeric wire into a liquid induces a substantial elastic compression due to the solid capillary pressure at the bottom. We quantitatively determine the effective surface tension from the elastic displacement field, and find a value comparable to the liquid-vapor surface tension. Most importantly, these results also reveal the way the liquid pulls on the solid close to the contact line: the capillary force is not oriented along the liquid-air interface, nor perpendicularly to the solid surface, as previously hypothesized, but towards the interior of the liquid.

References in corpus (3)

• The Deformation of an Elastic Substrate by a Three-Phase Contact Line
• Why is surface tension a force parallel to the interface?
• Elastic deformation due to tangential capillary forces

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• Surface energy of strained amorphous solids
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• Wrapping liquids, solids, and gases in thin sheets
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• The bending of an elastic beam by a liquid drop: A variational approach
• Geometry-driven folding of a floating annular sheet
• The role of crosslinking density in surface stress and surface energy of soft solids
• Soft wetting with (a)symmetric Shuttleworth effect
• Capillarity of soft amorphous solids: a microscopic model for surface stress
• On the singular nature of the elastocapillary ridge
• Soft beams: when capillarity induces axial compression