Fabrication of a superhydrophobic surface via spraying with polystyrene and multi-walled carbon nanotubes

A superhydrophobic surface was fabricated via spraying with polystyrene (PS) and multi-walled carbon nanotubes (MWCNTs). Spraying is one of the simplest and cheapest methods of fabricating superhydrophobic surfaces. First, MWCNTs were sonicated for 1 h with acetone solution and dried completely at room temperature. Acid-treated MWCNTs and PS were mixed with THF (tetrahydrofuran) solution for 5 h. Using the mixed MWCNT/PS solution, superhydrophobic cover-glass specimens were fabricated by the spraying technique. Spraying was performed by a simple airbrush having a 400-μm-diameter nozzle under the following spraying conditions: pressure of 2 bar, spraying distance from nozzle to specimen of 130 mm, and spraying time of 10, 20, or 30 s. After specimen fabrication, the superhydrophobicity of the surface was characterized via contact angle (CA) and sliding angle (SA) measurements using PS-sprayed specimens for reference. The specimen sprayed using PS (1 wt%)/MWCNT (0.08 wt%) mixture showed the highest superhydrophobicity (water CA = 163.8 ± 2.5°, water SA = 5.0 ± 0.9°) among the fabricated specimens in this study. Moreover, to observe the morphology of the fabricated specimens, field emission scanning electron microscopy (FESEM) was utilized. To analyze the nanostructures observed in the SEM images, Raman spectroscopy was utilized.