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Fabrication and Visualization of Capillary Bridges in Slit Pore Geometry
Published on: January 9, 2014
Kinetics of liquid annulus formation and capillary forces
Y I Rabinovich1, A Singh, M Hahn
1Particle Engineering Research Center, University of Florida, Gainesville, Florida 32611, United States.
Langmuir : the ACS Journal of Surfaces and Colloids
|September 28, 2011
Summary
Capillary adhesion force between silica surfaces depends on contact time at high humidity, driven by water annulus growth. Experimental results deviate significantly from diffusion theory, suggesting complex water transport mechanisms.
Area of Science:
- Surface Science
- Colloid and Surface Chemistry
- Nanotechnology
Background:
- Capillary adhesion forces are crucial in micro/nanoscale interactions.
- Understanding the time-dependence of these forces is essential for predicting material behavior.
Purpose of the Study:
- To experimentally investigate the dependence of capillary adhesion force on dwell-in time between silica surfaces.
- To explore the underlying mechanisms, particularly water annulus formation and growth kinetics.
Main Methods:
- Atomic Force Microscopy (AFM) was used to measure capillary adhesion force.
- Experiments were conducted at varying humidity levels.
- Analysis involved comparing experimental data with theoretical models of diffusion and viscous drainage.
Main Results:
- Capillary adhesion force showed a time-dependent, exponential increase at humidity >30-35% with characteristic times of ~10 s.
- Experimental kinetics of meniscus radius growth significantly deviated (by orders of magnitude) from theoretical predictions.
- Literature data for AFM cantilever-surface interactions showed similar deviations.
Conclusions:
- The kinetics of capillary adhesion are influenced by water annulus growth, involving vapor diffusion and drainage.
- Standard diffusion theory inadequately describes the observed phenomena.
- Deviations may be attributed to surface/Knudsen diffusion regimes, non-steady flow, tortuosity, or significantly altered water viscosity in confined geometries.
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