Development of Hydrophobic Coatings for Water-Repellent Surfaces Using Hybrid Methodology

Report No. ARL-TR-6898
Authors: Amanda S. Weerasooriya; Jacqueline Yim; Andres A. Bujanda; Daphne Pappas
Date/Pages: April 2014; 20 pages
Abstract: Hydrophobic surfaces are of considerable interest due to their self-cleaning, wicking, water-repellent, and antimicrobial properties. Several approaches have been investigated for the development of hydrophobic and superhydrophobic materials. One in particular involves introducing surface roughness and chemical functionalities with hydrophobic end groups. In this work, hydrophobic surfaces were incorporated on ultra-high-molecular-weight polyethylene films using a three-step process. A treatment by plasma was employed before any other significant treatments to help with better adherence of particles acquired through silane wet chemistry, which was implemented to introduce surface roughness to yield a hierarchical assembly of silicon oxide (SiO2) nanoparticles. This was followed by plasma-enhanced chemical vapor deposition (PECVD) at atmospheric pressure to deposit a coating composed of fluorinated groups on the material. The chemical composition, wettability, and morphology of the surface were studied using water contact angle, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy. Variations in the deposition processes of wet chemistry and PECVD were investigated. Fluorinated liquid precursors with different fluorocarbon structures and deposition time varied as well as the SiO2 nanoparticle loading. These parameters varied to obtain a surface with optimal distribution of particles coated with thin fluorocarbon films that exhibit hydrophobic behavior.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2014