Related Experiment Video
Updated: May 17, 2026
09:31
Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices
Published on: March 27, 2019
Contact angle and local wetting at contact line.
1School of Engineering, University of British Columbia, Kelowna, Canada. sunny.li@ubc.ca
Langmuir : the ACS Journal of Surfaces and Colloids
|October 17, 2012
Summary
The static contact angle is a local wetting parameter, not a global one. This study derives a general equation confirming its dependence on local surface chemistry and wetting at the contact line.
Area of Science:
- Surface Science
- Thermodynamics
- Wetting Phenomena
Background:
- The dependence of static contact angle on local wetting at the triple-phase contact line is not widely understood.
- Recent experimental and theoretical work suggests this relationship.
Purpose of the Study:
- To clarify the relationship between static contact angle and wetting.
- To derive a general equation for the static contact angle on composite surfaces.
Main Methods:
- Applied a global approach based on free surface energy.
- Applied a local approach considering forces at the contact line.
Main Results:
- Derived a general equation for the static contact angle.
- Showed the static contact angle depends on local surface chemistry and wetting state.
- Demonstrated agreement between global and local approaches.
Conclusions:
- The static contact angle is confirmed as a local wetting parameter.
- Wenzel and Cassie equations describe local wetting at the contact line, not global wetting.
More Related Videos
Related Concept Videos
01:13Contact Angle
When a solid is dipped inside a liquid, the liquid surface becomes curved near the contact. For some solid–liquid interfaces, the liquid is pulled up along the solid, while for others, the liquid surface is convex or depressed near the solid surface. This phenomenon can be explained using the concept of cohesive and adhesive forces.
The adhesive force is the molecular force between molecules of different materials, that is, between the molecules of the solid and the liquid. The cohesive force...
The adhesive force is the molecular force between molecules of different materials, that is, between the molecules of the solid and the liquid. The cohesive force...
01:24Surface Tension
Surface tension is defined as the force per unit length (γ) acting along the surface of a liquid. It arises due to strong intermolecular forces of attraction. A molecule located inside the bulk of the liquid is surrounded by other molecules and experiences equal forces in all directions. However, a molecule at the surface experiences unbalanced forces because there are more neighboring molecules below than above. This creates a net inward force that pulls surface molecules toward the interior,...
02:57Surface Tension, Capillary Action, and Viscosity
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
01:07Frictional Force
When a body is in motion, it encounters resistance because the body interacts with its surroundings. This resistance is known as friction, a common yet complex force whose behavior is still not completely understood. Friction opposes relative motion between systems in contact, but also allows us to move. Friction arises in part due to the roughness of surfaces in contact. For one object to move along a surface, it must rise to where the peaks of the surface can skip along the bottom of the...
01:22Surface Tension of Fluid
Surface tension is a fundamental property of fluids, occurring at the boundary between a liquid and a gas or between two immiscible liquids. This phenomenon arises from the cohesive forces between molecules at the fluid's surface, creating an effect similar to a stretched elastic membrane. Inside each fluid, molecules are equally attracted in all directions by neighboring molecules, but surface molecules experience a net inward force, resulting in surface tension.
Surface tension varies with...
Surface tension varies with...
01:16Surface Tension and Surface Energy
When a paint brush is immersed in water, the bristles wave freely inside the water. When it is taken out, the bristles stick together. The reason behind this effect is surface tension.
Consider a beaker filled with liquid. The bulk molecules in the liquid experience equal attractive forces on all sides with the surrounding molecules. However, the surface molecules experience a net attractive force downward due to the bulk molecules. The surface of the liquid behaves like a stretched membrane,...
Consider a beaker filled with liquid. The bulk molecules in the liquid experience equal attractive forces on all sides with the surrounding molecules. However, the surface molecules experience a net attractive force downward due to the bulk molecules. The surface of the liquid behaves like a stretched membrane,...