Superhydrophobic Surface by Replication of Laser Micromachined Pattern in Epoxy/Alumina Nanoparticle Composite

Abstract

Superhydrophobic surfaces were obtained by superposition of microstructure—defined by replication of laser micromachined masters, with nanostructure—created by durable epoxy/γ-Al₂O₃ nanoparticle composite, used for replication. Hierarchical surface topography thus obtained consisted of hexagonally spaced microcavities and nanoparticle agglomerates, exposed on the replica surface by radio frequency (RF) air plasma etching. Surface topography was further enhanced by rims around the microcavity edges, resulting from nanosecond laser micromachining defects in aluminum masters. Subsequent wet chemical hydrophobization with 1H,1H,2H,2H-perfluorotetradecyltriethoxysilane (PFTDTES) provided superhydrophobic behavior in replicas with a microcavity spacing of 30 μm, as indicated by a water contact angle of 160° and a sliding angle of 8°. The preparation method is relatively simple, inexpensive, and potentially scalable.