Bioinspired Nanomanufacturing of Graphene-embedded Superhydrophobic Surfaces with Mechanical and Chemical Robustness

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Super-hydrophobic surfaces with excellent water-repellent properties can find applications in various fields. However, many existing super-hydrophobic surfaces cannot endure mechanical wear nor chemical contamination. In addition, the hydrostatic pressure, evaporation, external force, and surface defects can also result in the loss of super-hydrophobicity. The challenge is to manufacture stable super-hydrophobic surfaces that can resist chemical and mechanical wear. Inspired by the robustness of the super-hydrophobicity associated with the lotus leaf, this award supports fundamental research to generate knowledge for a simple and inexpensive manufacturing process that integrates laser-scribing of multilayer graphene with soft lithography to create robust and durable super-hydrophobic surfaces. The availability of durable super-hydrophobic surfaces would impact several industries such as defense, energy, healthcare, biomedical, aerospace, electronics, and automotive, where water-repellent, antifouling and similar properties are needed, which would benefit the U.S. economy and society. The project focuses on broadening participation from women and underrepresented minority groups and provides them with a bridge toward research-related careers. It provides education and hands-on training in super-hydrophobic surfaces and nanomanufacturing to undergraduate, graduate, and high school students. This project addresses a central concern of super-hydrophobic surfaces, which is the lack of durability. The manufacturing process involves the use of laser-scribing of multilayer graphene to mimic lotus wax in combination with nanostructures by soft lithography to mimic the lotus papillae, thus creating an entirely new class of synthetic super-hydrophobic materials with exceptional stability under various challenging exposure conditions. However, the fundamental relationships between multilayer graphene thickness and mechanical and chemical durability and between the thermodynamic stability and the surface topology are still poorly understood. This project aims to cultivate fundamental knowledge of laser-scribing the multilayer graphene to enhance thermodynamic, chemical, and mechanical stability. The laser-scribing process reduces graphene oxide to graphene, thus capturing key lotus leaf features that would make the surface mechanically robust, while maintaining super-hydrophobicity. Moreover, the researched quantification of the thermodynamic and mechanical durability by measuring the critical Laplace pressure and the critical abrasion cycle at which the super-hydrophobicity is lost enables a systematic and thorough understanding of the underlying relationships among the characteristics of the graphene layer, pattern topology, and enhanced durability. Because multilayer graphene thickness and surface topology are design parameters, once understood, it can lay a solid foundation for the rational design of durable super-hydrophobic 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.