Materials Frontier No.153
Title: Mimic nature, beyond Nature: Multifunctional superhydrophobic surfaces
Speaker: Prof. Zuankai Wang, Department of Mechanical and Biomedical Engineering, the City University of Hong Kong, Hong Kong, P.R.China
Inviter: Prof Tao DENG
Zuankai Wang earned his Ph. D. degree in the Department of Mechanical, Aerospace and Nuclear Engineering at Rensselaer Polytechnic Institute in August 2008, after which he worked in the Department of Biomedical Engineering atColumbiaUniversityas a postdoctoral associate. He is currently an associate professor in the Department of Mechanical and Biomedical Engineering at theCityUniversityofHong Kong(CityU). His research work has been featured in many media reports including Nature News, BBC Radio’s Science in Action Program, Chemical & Engineering News, MaterialsViews, MaterialsViewsChina. Dr. Wang won the Best Paper Award in the Second and Third International Symposium on Optofluidics (2012, 2013), Materials Research Society Graduate Student Silver Award in 2007 Fall Meeting, and Chinese Government Outstanding Self‐Financed Students Abroad Award in 2007.
Various biological systems in nature orchestrate a high level of adaptability to their environments through the use of smart materials interface. This is exemplified by the lotus leaves which can keep self-cleaning even under dirty water, the small water striders which can elegantly slide on the water, and the beetles living in the dry desert which drink through the collection of tiny droplets in the air. One common feature of these biological systems lies in their special wettability of their surfaces (or superhydrophobic property), which are enabled by their unique micro/nanostructures and low surface energy. The structural and functional integrity in nature provides important insights for the rational design and creation of new classes of functional materials to solve some of the emerging challenges facing us.
In the first part of my talk, I will present the development of various superhydrophobic surfaces that significantly impact thermal-fluid processes including droplet impact, dropwise condensation, evaporation and freezing. We show that by harnessing the synergistic cooperation between the hierarchical structures, we can dramatically reduce the theoretical contact time limit, enhance the droplet nucleation and departure simultaneously, prevent the Cassie-to-Wenzel transition during the evaporation process, and delay the frost/ice formation. Lastly, I will discuss the application of hydrophobic/superhydrophobic surfaces for enhanced antibacterial activity.