Simple fabrication of superoleophobic titanium surfaces via hierarchical microhorn/nanoporous structure growth by chemical acid etching and anodization

Abstract

Titanium substrate surfaces were rendered superoleophobic by forming hierarchical microhorn/nanopore structures using a facile and cost-effective approach: acid etching and anodization followed by fluorination. The conditions of acid etching and anodization were finely optimized to obtain the best re-entrant structure for the superoleophobic surface. A fluorosilane self-assembled monolayer (SAM) coating on the surface significantly lowered the surface energy, and thereby imparted superoleophobicity, without damaging the hierarchical structure. To evaluate the superoleophobicity, surface contact angles and sliding angles of various liquids with different surface tensions were measured. All the tested liquids, including hexadecane (low surface tension, 27.1 mN/m at 25 degrees C), exhibited contact angles greater than 150 degrees on the fluorinated hierarchical microhorn/nanoporous surfaces. (C) 2017 Elsevier B.V. All rights reserved.