Knowra Wetting Wetting Wetting is the spreading or adhesion of a liquid on a solid surface, governed by the balance of solid–vapor, solid–liquid, and liquid–vapor interfacial energies.
Contact angle : The angle at which a liquid–vapor interface meets a solid surface, measured through the liquid. It provides the standard geometric measure of how strongly a liquid wets a surface.
Surface tension : The energy cost per unit area, or force per unit length, associated with a liquid interface. It is the liquid–vapor interfacial tension in wetting balances.
Coating : The application of a material as a continuous or patterned layer over a surface. Good coating coverage requires the liquid precursor to wet the substrate appropriately.
Partial wetting : A wetting regime in which a liquid forms a finite-angle contact with a solid at equilibrium. It is the regime where droplets remain rather than spreading into a film.
Young's equation : An equation relating the equilibrium contact angle to the interfacial tensions of a solid, liquid, and vapor. It connects wetting’s interfacial-energy balance to the observed contact angle.
Interfacial energy : The excess free energy associated with the boundary between two phases. Wetting depends on the energies of the solid–liquid, solid–vapor, and liquid–vapor boundaries.
Imbibition : The spontaneous uptake of a liquid into a porous material, driven by capillary forces. It describes wetting-driven liquid entry into porous solids.
Complete wetting : A wetting regime in which a liquid spreads as a macroscopic film over a solid at equilibrium. It marks the limiting case in which the equilibrium contact angle is zero.
Young–Dupré equation : A relation between contact angle, liquid surface tension, and the work of adhesion between a liquid and solid. It quantifies the adhesion underlying a liquid’s tendency to wet a solid.
Free energy : A thermodynamic potential that measures the energy available to drive change under specified conditions. Equilibrium wetting minimizes the relevant free energy of the interfaces.
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