Textured superhydrophobic films on copper prepared using solvent-free methods exhibiting antifouling properties

Development of superhydrophobic materials is in constant evolution due to their multiple applications. Recent investigations have shown that a stable and reliable superhydrophobic performance requires the use of hierarchical structures. In this work, we have engineered superhydrophobic copper surfaces using an innovative solution-free procedure to fabricate hierarchical structures. First, sequential cycles of O₂- and Ar-plasma etching were performed on the copper substrate to generate microtexture. Secondly, a fluoropolymer was deposited on top of the metal via initiated chemical vapor deposition (iCVD). The organic layer conformally coated the copper substrate maintaining the previously etched geometry. Moreover, the polymer displayed a very characteristic and unique structure with small protuberances arising out from the film in a nanoworm-like morphology. These nanofeatures together with the microroughness, induced by plasma etching, resulted in a hierarchical structure that confers superhydrophobic properties to copper. Water contact angle (WCA) as high as 168° and WCA hysteresis of 2° were measured for the treated samples. The superhydrophobic iCVD polymer was tested as an antifouling coating. Samples were exposed to Pseudomonas fluorescens for 24 h and the attachment of the microorganisms was reduced by 57% compared to uncoated copper.