Cover article in Langmuir: switching a meniscus with temperature

Our paper An Experimental Study of Interfacial Dynamics Control Using Temperature-Sensitive Surfactants is out in Langmuir, and it was selected as a cover article for the May 26, 2026 issue (Vol. 42, No. 20)!

The shape of a meniscus, whether it curves in (concave) or out (convex), controls how liquids wet surfaces and move through small channels. Normally that shape is fixed. In this study, Amirhosein Sarchami showed that by adding temperature-sensitive surfactants to both the water and the oil phases, a modest temperature change can reversibly flip an oil–water meniscus between concave and convex. The switching temperature can be tuned through the surfactant composition and concentration.

The experiments also revealed a thermal hysteresis in the contact angle: the interface behaves differently when it is heated than when it is cooled. We attribute this to asymmetric adsorption and desorption of surfactant and to interfacial freezing. Together, the results give design principles for programmable, reversible wettability control, with possible uses in microfluidics, thermal management, and adaptive surfaces.

It’s a special paper for the lab. It brings together a PhD candidate (Amirhosein), an undergraduate researcher (Saaras Pakanati), and a PhD student (Ayaaz Yasin), along with our UC colleague Prof. Milind Jog. It also pairs with Amirhosein’s computational work on pore-scale flow regime tuning, which applies the same switchable-wettability idea to flow through porous media.

The paper is open access. Read it here, and see more on our oil–water interfacial dynamics research page.