Tailoring of Superhydrophilic to Superhydrophobic Coating Morphologies for Space Exploration Contamination Control

摘要

Dust and ice contamination is a serious problem for equipment and vehicles for air and space mission applications. Dust contamination gathers on photonic sensors inhibiting motion and data gathering. Photonic devices that require transparency to light for maximum efficiency, such as solar photovoltaic power systems, video cameras and optical or infrared detectors, can be seriously affected by dust accumulation. The lunar thermal and radiation environment also pose unique challenges because of its large temperature variations and its interaction with the local plasma environment and solar UV and X-rays induced photoemission of electrons. Superhydrophilic materials are composed of polar molecules and have been used to defog glass, enable oil spots to be swept away easily with water, as door mirrors for cars and coatings for buildings. Hydrophobic molecules tend to be non-polar and thus prefer other neutral molecules and nonpolar solvents. Hydrophobic molecules often cluster together. Hydrophobic surfaces contain materials that are difficult to wet with liquids, with superhyrophobic surfaces having contact angles in excess of 150° (the equilibrium angle of contact of a liquid on a rigid surface where liquid, solid and gas phases meet). This paper presents an overview of the fundamental forces (van der Waals) which allows certain contamination to adhere to critical photonic surfaces and the various passive coatings phenomenology (hydrophilic to hydrophobic) that is used to minimize this contamination.