​ ​Seminar on Underliquid Wetting: Fundamentals and Applications

Wetting characteristics of a given substrate are of paramount importance for material discovery. We have developed a new method which allows us to characterize any underliquid substrate (superhydrophobic/superoleophobic) using needle-free drop deposition technique. We have also derived a new lubrication equation to characterize the coalescence behavior of two drops on underliquid substrates. Further, we demonstrate that for underliquid wetting of pillared substrates, there exists a meta-stable Cassie-Baxter state. Careful experiments conducted with oil drop in water and water drop in oil reveal the presence of a thin liquid layer between the drop and the submerged substrate, which accounts for the discrepancy between the experimental data and the theoretical predictions based on Young’s equation. Finally, using the needle-free drop deposition technique, underwater superoleophobicity of a glass surface and fish scales are characterized and also development of a new underwater oleophobic surface is demonstrated.

Sushanta Mitra is the Executive Director of the Waterloo Institute for Nanotechnology and a Professor in Mechanical and Mechatronics Engineering and cross-appointed to the Departments of Physics & Astronomy and Chemical Engineering at the University of Waterloo. His research interests are in the fundamental understanding of fluid transport in micro and nano-scale confinements with applications in energy, water, and bio-systems. For his contributions in engineering and sciences, he is an elected fellow of number of key scientific organizations including the Canadian Academy for Engineering, the Royal Society of Chemistry, the American Physical Society, and the American Association for the Advancement of Science. He is also the recipient of 2015 Engineering Excellence Medal from the Ontario Society of Professional Engineers.