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° 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. An extremely water and oil repellent surface is created by a one‐step growth of worm‐like fluoropolymer structures on planar substrates using initiated chemical vapor deposition (iCVD). By controlling iCVD conditions and without prior substrate roughening or patterning, worm structures instead of conformal films can be achieved. Worm growth is driven by in‐plane crystallization that is favorable under slow deposition kinetics.