Coulombwet

Coulombwet is a term used in surface science to describe a framework for understanding and controlling the wetting of liquids on solid surfaces through Coulombic interactions.

The concept emphasizes the role of surface charge distribution and electrostatic forces in determining the contact angle and spreading behavior of liquids, complementing traditional capillarity and surface tension models.

In practice, Coulombwet integrates electrostatic contributions into wetting models by adding a term dependent on surface charge density, dielectric properties, and the electric double layer, and it can include charge-induced flows near the contact line.

Experimental approaches involve sessile-drop measurements on conductive or adjustable-charge substrates, using controlled charging protocols and polar liquids or ionic liquids, with measurements of apparent contact angle, hysteresis, and spreading rate.

Applications include microfluidics, lab-on-a-chip devices, and coating processes where electric fields or surface charging control spreading, pinning, or dewetting.

As a field, Coulombwet is debated with respect to its distinction from electrowetting and electrocapillarity, particularly at small scales or high ionic strength, where definitions and measurements may diverge. Researchers emphasize careful definition of measurable quantities such as the apparent contact angle under a fixed surface charge. Related topics include electrowetting, electrocapillarity, contact-angle hysteresis, and surface-charge modulation.