CAREER: Towards A Paradigm of Sustainable Liquid Repellent Surfaces

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This Faculty Early Career Development Program (CAREER) award supports research that will contribute new fundamental knowledge in the field of surface science, related to liquid-repellent surfaces (often called non-stick coatings). Typically, liquid-repellent surfaces are made with long chain fluorocarbon materials. However, long chain fluorocarbon materials are rapidly being phased out because of the growing concerns regarding their negative environmental and biological impacts. This research promotes national health by developing alternative surface treatments to the currently used toxic bio-accumulating materials. New hydro- and omniphobic materials are increasingly in demand for defense and commercial applications in textiles, surface coatings in harsh or "dirty" environments, among others. The work advances the science of surface repellents by providing the basic knowledge needed to design novel liquid-repellent surfaces with the more benign short chain fluorocarbon materials and with performance (i.e., degree of liquid repellency) equivalent to the long chain fluorocarbon materials. Such innovative liquid-repellent surfaces have the potential to drastically alter the non-stick coatings technology landscape in civilian, industrial and defense sectors. Therefore, the results and insights from this research will be significantly beneficial to the U.S. economy and society. The education activities are integrated with this research through the generation of STEM education kits and do-it-yourself (DIY) videos on "Fun with Surface" to be used in K-12 science classes in conjunction with teacher training workshops.Liquid-repellent surfaces consisting of long chain fluorocarbons (i.e., linear molecules with 8 or more fully fluorinated carbons) decompose into perfluorooctanoic acid, which is bio-accumulative and is considered an emerging contaminant. So, it is essential to develop alternative sustainable materials (e.g., short chain fluorocarbons) that can be as liquid-repellent as long chain fluorocarbons. The research is based on the hypothesis that short chain fluorocarbons with high surface crystallinity and re-entrant morphology will offer liquid-repellency equivalent to long chain fluorocarbons. To test this hypothesis, the research team will systematically investigate the influence of molecular architecture of fluorocarbon surface ligands and surface modification reaction coordinates on surface crystallinity and morphology. The resulting liquid-repellency will be investigated experimentally and compared with theoretical predictions. Overall, this research will provide a thorough understanding of molecular architecture-processing-structure-property relationships involved in design of liquid-repellent surfaces and pave the way to a paradigm of sustainable liquid-repellent surfaces.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.