One-step deposition of stable superhydrophobic coatings with controllable wettability

Abstract

A superhydrophobic coating was prepared on copper (Cu) foam by a one-step chemical deposition technique. The as-prepared coated copper foam displayed excellent superhydrophobicity (water contact angle of ∼153.5° and water sliding angle of ∼1°) with a typical surface micro–nano rough structure at a deposition temperature of 60°C and a deposition time of 20 min. The film was composed of cuprous sulfide (Cu2S) and copper tetradecanoate, which revealed the reaction mechanism. The as-prepared superhydrophobic copper foam maintained its superhydrophobicity under harsh environmental conditions (alkaline, weakly acidic, salty, long-term storage and mechanical abrasion). The as-prepared surface was still superhydrophobic after 600 mm abrasion, with a contact angle above 150.2 ± 0.2° and a sliding angle below 10°. Through the method of heat treatment and the modification of myristic acid, the surface achieved a rapid transition in wettability, with the contact angle maintaining stability for 20 cycles. The superhydrophobic film was repeatedly soaked in a mud–water mixture 20 times, and it remained silt-free, indicating excellent self-cleaning and antifouling features. More importantly, the modified copper foam can effectively separate a series of oil–water mixtures with high efficiency (>94%) even after five cycles. Thus, the presented superhydrophobic material with dual functionality is a promising candidate for application in efficient oil–water separation.