Start
Nov 30, 2017 - 16:00
End
Nov 30, 2017 - 17:00
Venue
Room 230 Chemical Engg Dept
Event Type
Speaker
Prof. Noshir Pesika Tulane University USA
Title
Tuning Surface Forces and Interactions – from Mosquito Adhesion to Reversible Potential Dependent Friction
Abstract: In this talk I will present some of our recent work involving the adhesion of mosquitoes to surfaces. Specifically using AFM force measurements we are able to better understand the interactions between the hierarchical micro- and nanoscale structures on a mosquito foot and surfaces with different levels of roughness and wetting properties. We show that the origin of the surface adhesion is through van der Waals interactions however capillary forces can also contribute to the overall adhesion when the opposing surface is hydrophilic. In the second project I will show how the friction between an AFM probe and a Au(111) surface under aqueous saline solutions can be controlled reversibly by the surface electrical potential. We attribute this phenomenon to the highly viscous layer (also referred to as ice-like water) of water that forms at the electrode/electrolyte interface when anodic potentials are applied which results in high friction (CoF = 3.1). However when cathodic potentials are applied the friction is lower (CoF = 0.12).Bio: Dr. Pesika is an Associate Professor in the Chemical and Biomolecular Engineering department at Tulane University New Orleans Louisiana USA. The overarching theme of his current research is the development of “smart” materials; i.e. materials that have been judiciously designed (through surface chemistry or topography) to perform a function when stimulated externally or offer enhanced properties based on their design. His research group consists primarily of experimentalists although his approach relies heavily on a fundamental understanding of the underlying physics before the development of applied “smart” materials. Examples of such materials include biomimetic directional adhesives anisotropic catalysts with enhanced catalytic activity novel oil dispersant formulations which prevent oil from adhering to marine surfaces and ultra-low friction surfaces and lubricants formulations. The projects have been supported by the National Science Foundation Gulf of Mexico Research Initiative and the Louisiana Board of Regents.