Thermodiffusion as a means to manipulate liquid film dynamics on chemically patterned surfaces

Abstract

The model problem examined here is the stability of a thin liquid film consisting of two miscible components, resting on a chemically patterned solid substrate and heated from below. In addition to surface tension gradients, the temperature variations also induce gradients in the concentration of the film by virtue of thermodiffusion/Soret effects. We study the stability and dewetting behaviour due to the coupled interplay between thermal gradients, Soret effects, long-range van der Waals forces, and wettability gradient-driven flows. Linear stability analysis is first employed to predict growth rates and the critical Marangoni number for chemically homogeneous surfaces. Then, nonlinear simulations are performed to unravel the interfacial dynamics and possible locations of the film rupture on chemically patterned substrates. Results suggest that appropriate tuning of the Soret parameter and its direction, in conjunction with either heating or cooling, can help manipulate the location and time scales of the film rupture. The Soret effect can either potentially aid or oppose film instability depending on whether the thermal and solutal contributions to flow are cooperative or opposed to each other.

Epoxy-glass Microballoon Syntactic Foams for Blast Mitigating Applications

“…Rigid polymeric foams, usually prepared by the chemical reaction of isocyanates with polyols, are not strong enough to withstand blast loads and therefore mandate reinforcement 13 . Also, the processing of polymer-based foams is an involved process with interfacial phenomena and fluid dynamics being very critical 14,15 . In the field of defence technologies, in view of their excellent mechanical properties syntactic foams have been reported to withstand dynamic loads 16 .…”