Graphene as a Multifunctional Superamphiphobic Surface Material

A novel, economic, and simple method for the attachment of fluorine molecules onto graphene (G) structures to obtain surfaces that are super repellent toward relatively low surface-tension liquids is presented. We report super repellency of G films toward various liquids with contact angles (CAs) of 170° for water and more than 150° for both glycerol and ethylene glycol, respectively. In addition, a very low water droplet sliding angle (SA) of less than 2° was observed. Fluorine molecules were introduced on the G surface by dispersing G flakes in trifluorotoluene (TFT) under sonication and mixing. The resulting functionalized G flakes were airbrushed onto glass substrates, and various microscopic techniques such as tunneling electron microscopy (TEM) and scanning electron microscopy (SEM) were used to characterize their surface morphology and properties. Modification of G surfaces with TFT was further confirmed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Two factors, double scale roughness and low surface energy, contributed to the super repellency of the G-TFT films for various liquids. Anti-icing tests of the G-TFT film also showed a significant delay in the freezing of water droplets of six times compared to bare aluminum sheet. To prove the flexibility of this approach, transparent and flexible superhydrophobic (SHP) coatings were fabricated by coating a plastic substrate with a thin layer of G-TFT film. This super repellency of G-TFT coatings toward various liquids, including some organic liquids could see industrial applications in the fabrication of self-cleaning, anti-icing, and biotechnological surfaces.