Abstract:

Nature, such as plants, insects, and marine animals, uses micro/nano-textured surfaces in their components (e.g., leaves, wings, eyes, legs, and skins) for multiple purposes, such as water-repellency, anti-adhesiveness, and self-cleanness. Such multifunctional surface properties are attributed to three-dimensional surface structures with modulated surface wettability. For example, hydrophobic surface structures create a composite interface with liquid by retaining air between the structures, minimizing the contact area with liquid. Such non-wetting surface property, so-called superhydrophobicity, can offer numerous application potentials, such as hydrodynamic drag reduction, anti-biofouling, anti-corrosion, anti-fogging, anti-frosting, and anti-icing.  Over the last couple of decades, we have witnessed a significant advancement in the understanding of surface superhydrophobicity as well as the design, fabrication, and applications of superhydrophobic coatings/surfaces/materials. In this talk, the designs, fabrications, and applications of superhydrophobic surfaces for multifunctionalities will be presented, including hydrodynamic friction reduction, anti-biofouling, anti-corrosion, and anti-icing. To overcome the issues of air depletion in the real applications of superhydrophobic surfaces, oil-impregnated porous surfaces have also recently been explored for such applications, where the water-immiscible lubricating liquid (oil) is infused into the porous structures, providing similar effects. The designs, fabrications, and applications of such oil-impregnated nanoporous surfaces for multifunctionalities will also be presented, in comparison with superhydrophobic surfaces.

Biography:

Dr. Chang-Hwan Choi is a Full Professor in the Department of Mechanical Engineering at the Stevens Institute of Technology in US. Dr. Choi received his PhD in Mechanical Engineering from the University of California at Los Angeles (UCLA) in 2006, specializing in MEMS/Nanotechnology and minoring in Fluid Mechanics and Biomedical Engineering. He earned his MS in Fluids, Thermal, and Chemical Processes from Brown University in 2002. Before he moved to US, he acquired his BS (1995) and MS (1997) in Mechanical & Aerospace Engineering from Seoul National University in Korea. He also has two-year (1996, 2000) work experience at Korea Aerospace Research Institute and three-year (1997-1999) teaching experience at Chandrakasem Rajabhat University in Thailand. His current research activities include large-area nanopatterning, superhydrophobic surface engineering and its applications (e.g., hydrodynamic drag reduction, anti-corrosion, anti-biofouling, and anti-icing), fluid/thermal physics at nanoscale interfaces, self-assembly of nanomaterials, nanofluidic energy harvesting, and cell-material interactions. He is a recipient of the 2010 Young Investigator Program (YIP) award by the US Office of Naval Research (ONR) for his efforts in the development of 3D nanostructures for hydrodynamically-efficient anti-biofouling and anti-corrosive surfaces. In 2015, he was also awarded the Humboldt Research Fellowship for Experienced Researchers by the Alexander von Humboldt Foundation.