A Nano-modified Superhydrophobic Membrane

This paper focuses on the synthesis of super-hydrophobic membranes. The polymer used in this research is polystyrene (PS), which has low surface energy but not low enough to be characterized as a superhydrophobic material. As hydrophobicity is based on low energy surface and surface roughness, the electrospinning technique was selected as the manufacturing technique. N, N' dimethylformamide (DMF) was employed as the PS solvent. Two groups of PS/DMF solutions were investigated i.e. 20/80 and 35/65. To increase even more the hydrophobicity, nanoparticles of silica, graphene, cadmium, and zinc were dispersed into the PS/DMF solutions. In contrast to results previous published in literature, the PS/DMF weight ratio of 20/80 led to water contact angles (WCA) of 148 degrees, which is higher than the contact angle for the 35/65 ratio, i.e. 143 degrees. This fact seems to be due to the presence of non-evaporated solvent into the PS surface as the 35/65 solution was more viscous. The WCA for membranes with 0.5 wt. (%) of graphene reached 152 degrees, 149 degrees-153 degrees for membranes with nanosilica addition, 151 degrees with 5.0 wt. (%) CdS, and 153 degrees, 163 degrees and 168 degrees with the addition of 5 wt. (%), 10 wt. (%) and 15 wt. (%) of ZnS, respectively.