Tom Krupenkin
Mechanical Engineering,
University of Wisconsin - Madison
Abstract:
Over the last decade, continuing progress in nanofabrication techniques
led to substantial advancement in our understanding of the physics and
chemistry of the liquid-solid and liquid-gas interfaces at the mesoscopic
scale and brought the advent of a new area that can be loosely called
nanoscale interface engineering. The main goal of this new field is to
employ the nano and micro scale interfacial features, such as nano-topography,
to obtain surfaces and materials with the radically new and previously
unattainable properties.
In this talk I will primarily concentrate on the influence of the nano-scale topography on the wetting properties of solid surfaces. Three examples of novel topographies: "nanograss", "nanofur", and "nanonails" will be discussed. Nanograss and nanofur are examples of dynamically tunable nanostructured surfaces. The behavior of these surfaces can be reversibly switched between superhydrophobic and hydrophilic states either actively, by the application of electrical voltage, or passively, in response to the change in environmental conditions such as humidity. Nanonails represent a novel type of nanostructured surface that resists wetting by "locking" the liquid in a strongly metastable non-wetting state. This leads to "superlyophobic" surfaces that repel virtually any liquid even if the surface material by itself is highly wettable.
Potential applications of these systems span an exceptionally broad range, which includes areas as diverse as self-cleaning coatings, controllable permeability membranes for portable power generation, substrates for directed biological cell migration and differentiation, and hydrodynamic drag reduction surfaces. Several examples of these novel applications will be discussed in detail, including droplet-based microfluidics, reserve microbattery-on-a-chip, and drag reduction.
2009 Run
Sept. 23rd to Nov. 10th
