One-Step Bottom-Up Growth of Highly Liquid Repellent Worm-Like Surfaces on Planar Substrates

Highly liquid repellent (superhydrophobic, superoleophobic) surfaces are fabricated using mostly top-down approaches and liquid-based processing. Top-down approaches, like lithography and templating, are highly process-intensive, while liquid-based processing, like etching and fluoropolymer solution coating, rely on solvents that often damage the substrate. Ultimately, to suppress liquids from spreading, the goal is to create a surface with low surface energy and a hierarchically roughened topology. Here, a bottom-up approach that achieves these two prerequisite criteria in one single step is demonstrated. Relying on a liquid-free initiated chemical vapor deposition (iCVD) process, worm-like protrusions of a semicrystalline fluoropolymer (poly(perfluorodecyl acrylate)) directly grow on flat substrates without prior surface pretreatment. The nano/microworm surfaces display super-liquid repellency (>150 degrees contact angle) to water and oil. Worm formation (as opposed to conformal thin film formation) is attributed to preferential crystal nucleation, orientation, and growth on the substrate plane.