Simple processes for the preparation of superhydrophobic polymer surfaces

Two simple processes; (i) spin-coating, and (ii) doctor blade coating of silica/polymer dispersions are described for the preparation of superhydrophobic polymer surfaces. To demonstrate the versatility and broad applicability of the processes, polymeric surfaces modified included a thermoplastic resin, polystyrene (PS) and a thermoset, crosslinked epoxy resin (ER). Micro/nano hierarchical nature of the surface topographies obtained were demonstrated by scanning electron microscopy (SEM), atomic force microscopy (AFM) and white light interferometry (WLI) studies. Roughness factor (r) and average surface roughness (Ra) values, which are critical in obtaining superhydrophobic surfaces were determined for each polymeric system. It was clearly demonstrated that increased (r) and (Ra) values resulted in superhydrophobic behavior with very high static, advancing and receding water contact angles, well above 150° and contact angle hysteresis values of less than 10°. Incorporation of small amounts (1.0% by weight) of a silicone copolymer or a perfluoroether glycol oligomer reduced the contact angle hysteresis in the epoxy resin system well below 10° and produced truly superhydrophobic surfaces. [Display omitted] •Superhydrophobic polystyrene and epoxy resin coatings were prepared by using silica/polymer dispersions.•Formation of micro/nano hierarchical surface topographies were demonstrated by SEM, AFM and interferometric techniques.•Coatings displayed water contact angles well above 150° and contact angle hysteresis below 10°.•Coated surfaces obtained were robust, durable and maintained their superhydrophobicity after a year of storage.•Wenzel roughness factor (r) and average surface roughness (Ra) values were determined.