Electrochemical synthesis of biomimetic micro-nano structured super-hydrophobic thin films

Abstract

Micro-nano structured super-hydrophobic coatings were successfully fabricated on biomimetic Au-film surfaces via a cathodic one-step electrodeposition method. The micro-structure of natural, hydrophobic plant surfaces was imprinted on cellulose acetate films and gold sputtered in order to create 70-100 nm thin, biomimetic Au-films. Two solutions for electrodeposition were studied: An ethanolic solution of myristic acid and lanthanum chloride, and an ethanolic solution of myristic acid and manganese chloride. The cathodic electrodeposition was performed in a two-electrode cell, with a biomimetic Au-film serving as the cathode, and a carbon electrode as the anode. After electrodeposition on the biomimetic Au substrates, the static contact angles of the coatings improved and were as high as 156° for the lanthanum myristate depositions, and 140° for the manganese myristate depositions. The sliding contact angles for both myristate coatings on the biomimetic substrates were less than 2°. The results indicate that a biomimetic substrate improves the hydrophobic properties of the surface. Deposition time and applied voltage were studied as variables, focusing on their influence on each coating’s contact angle, adhesion and substrate coverage. It was observed that tunable adhesion can be achieved for the manganese myristate depositions, showing a potential for future biomedical and lab-on-chip applications.