Wetings

Wetings is a term used in materials science to describe rapid changes in a liquid’s adhesion to a solid surface that occur when the surface is textured or chemically heterogeneous. The concept refers to abrupt transitions between distinct wetting states, rather than gradual changes in contact angle alone. Wetings highlight the role of energy barriers and metastable configurations in micro- and nano-scale roughness.

In a typical Wetings scenario, a liquid on a rough surface may occupy one of two stable states: a Wenzel state, in which the liquid fully wets the roughness, or a Cassie-Baxter state, in which trapped pockets of air reduce contact. Under certain stimuli—such as pressure changes, chemical exposure, or environmental shifts—the system can switch from one state to the other, often accompanied by a sudden change in apparent contact angle and droplet mobility.

Causes of Wetings include the scale and pattern of surface roughness, chemical heterogeneity, and confinement within microchannels. Controlling Wetings is of interest for designing resilient coatings, self-cleaning surfaces, anti-fouling technologies, and for improving printing and microfluidic device performance.

Historically, Wetings emerged from studies of dynamic wetting and interfacial energy landscapes, with observations linking state transitions to controllable external factors. See also wetting, contact angle, Wenzel model, Cassie-Baxter model, capillarity, and microfluidics.