Jan 2020
Abstract:
Identifying, describing, and understanding the rich structural and functional effects that occur when water interfaces with hydrophobic media, such as air, hydrocarbons, or perfluorocarbons, forms the foundation of my group’s multi-disciplinary research. These “water-hydrophobe interfaces,” are present in a wide range of natural processes, ranging from thundercloud charging and cloud chemistry, to the formation of gas-hydrates and lipid vesicles, through to the uptake and release of water in vegetation and soils. Given the encompassing scope of water-hydrophobe interactions, the research performed within my group traverses both applied and fundamental aspects. In this colloquium, I will showcase our multiscale investigation of water-hydrophobe interfaces over length scales of some eleven orders of magnitude. Our efforts range from measuring hydrophobic forces between surfaces at sub-nanometer separations, to studying chemical reactions on microdroplets of water in air and oils, and from designing insect-inspired, perfluorocarbon-free water-repellent coatings and membranes at the centimeter scale, to conducting agricultural field trials of our technologies for growing more food with less water in plots 60 m on a side (Fig.1). I will also share my vision for future research.
Fig. 1| At a glance: our multiscale investigations of water. (A) Measuring water-mediated forces between macroscopic surfaces at sub-nanometer resolution; (B) Probing the chemical activity of molecules and ions in micron-scale water droplets suspended in air and oils; (C) Understanding the factors leading to the superhydrophobicity of millimeter-scale sea-skaters (Halobates Germanus); (D) Our patent-pending superhydrophobic sand mulches for growing more food with less water in arid and semi-arid climates. (Credits: Illustrations A-B, and C, respectively, by Xavier Pita and Ivan Gromicho, Scientific Illustrators at KAUST; Photo D: Adair Gallo Jr.)
Bio:
Himanshu Mishra is an Assistant Professor of Environmental Science and Engineering and a principal investigator at the Water Desalination and Reuse Center at KAUST. His group investigates physical and chemical phenomena at interfaces of water with air, oils, and perfluorinated coatings, such as wetting, surface forces, electrification, and chemical reactions. Technologies developed in his group range from superhydrophobic sand mulches (SandX) for boosting crop-yields in arid areas to coating-free gas-entrapping membranes (GEMs) for greener membrane distillation. Articles based on his work have appeared in Nature Communications, Science Advances, Proceedings of the National Academy of Sciences, the Journal of Colloid and Interface Science, and journals of the American Chemical Society and the Royal Society of Chemistry. He holds seven patents (granted or pending).