Wettabilityn

Wettabilityn is not a standard term in surface science and is usually encountered as a typographical variant of wettability. Wettability describes how readily a liquid spreads on or adheres to a solid surface. It is commonly quantified by the contact angle formed where the liquid, solid, and air meet. Small contact angles (typically below 90 degrees) indicate good wetting; angles above 90 degrees indicate poor wetting. Surfaces with contact angles above about 150 degrees and low contact-angle hysteresis are described as superhydrophobic.

Measurements of wettability include static contact angle determination via goniometry, such as the sessile-drop method. Dynamic measurements for advancing and receding angles reveal hysteresis. Other methods include the Wilhelmy plate technique and capillary rise, each providing different perspectives on liquid–solid interactions.

Principles underlying wettability are framed by interfacial science. Young's equation relates the contact angle to the interfacial tensions at the solid–liquid, solid–gas, and liquid–gas interfaces. Real surfaces deviate from ideal behavior due to roughness, chemical heterogeneity, or texture. The Wenzel model accounts for rough surfaces, while the Cassie–Baxter model describes composite surfaces with trapped air or other phases affecting spreading.

Key factors influencing wettability include the surface energy and chemical composition of the solid, surface roughness and morphology, contamination, and temperature, as well as liquid properties such as surface tension and polarity.

Applications span coating and paint formulation, inkjet printing, microfluidics, enhanced oil recovery, anti-icing, self-cleaning, and textile engineering. Wettability can be engineered by surface treatment, chemical grafting, plasma processing, texturing, or applying specialized coatings to tailor spreading and adhesion for specific goals.

Natural and engineered systems rely on wettability to manage liquid spreading, adhesion, and transport at interfaces.