HEMI Seminar: Chris Wohl (NASA)

Mitigating Contaminant Adhesion on Aerospace Surfaces

Chrisopher J. Wohl

Advanced Materials and Processing Branch, NASA Langley Research Center

Abhesive, non-stick surfaces are achieved in natural systems through practical, efficient strategies based on both surface chemistry and topography. Surfaces such as a Lotus leaf and shark skin can be strikingly different, yet they achieve the same goal of preventing surface contamination by controlling interfacial interactions. Although replication of these properties for an array of applications has been demonstrated, extending this strategy to extreme environments such as the leading edge of an aircraft or the Lunar surface presents a unique set of challenges. Future aircraft that utilize laminar flow to a greater extent than current aircraft designs will require contaminant-free wing leading edges to maintain efficient fuel burn rates. Similarly, long-term manned or robotic exploration missions in extraterrestrial environments will require abhesive surfaces for sustaining seals, in-situ characterization instrumentation, power generation, etc. Surface designs for these applications require leveraging the beneficial materials properties of high performance polymeric materials while controlling surface properties to achieve the desired abhesive behavior. This talk will describe the use of surface modifying agents, along with topographical modification of epoxy and polyimide materials, to achieve abhesion while maintaining necessary mechanical, thermal, and durability properties.

Christopher J. Wohl, Ph.D. is a senior research scientist in the Advanced Materials and Processing Branch at the NASA Langley Research Center in Hampton, VA.  He has experience in a variety of fields including physical, polymeric, and organic chemistry, laser spectroscopy, kinetics, and surface and interfacial sciences.  He has researched the generation, characterization, and modification of novel materials for adhesion mitigation involving surface engineering and self-organizing systems.  He has also been involved with process identification and modification for surface preparation of adhesively bonded interfaces including both composite and metallic substrates.  He received a B.S. (Chemistry) from Virginia Polytechnic Institute and State University in 2002 and a Ph.D. (Physical Chemistry) from Virginia Commonwealth University in 2006.  He is the author or coauthor of 32 peer reviewed journal articles, 65 other referenceable publications (conference proceedings), 26 invention disclosures, 13 patent applications, and 5 issued patents.  He has received several awards including the NASA Exceptional Technology Achievement Medal in 2018, an Aviation Week Laureate Award in 2016, the NASA ARMD Associate Administrator Award in 2016, a NASA Group Achievement Award in 2014 for flight testing insect adhesion mitigation coatings, the NASA Langley Engineering Directorate Innovation Award in 2011 (part of a six member team), among others.