Facile transformation of a native polystyrene (PS) film into a stable superhydrophobic surface via sol-gel process

Facile transformation of a native polystyrene (PS) film into a stable superhydrophobic surface through sol-gel process was investigated. An MPS-grafted colloidal silica sols by the synthetic route was fabricated. The reaction mixture were prepared by mixing tetraethyl orthosilicate, TEOS and methacryloxypropyltrimethoxysilane (MPS) with N,N'-dimethylformamide (DMF). Then the reaction of the mixture occurred at 60°C for 5h after adding deionized water and little hydrochloric acid solution. The inset magnification image clearly displays the size of MPS-functionalized silica cores that ranges from 40 to 80 nm, and that of PS shell is about 30 nm. Two kinds of sample were also prepared by spin-coating the corresponding solution onto clean glass substrates, and drying them at room temperature to compare the water contact angle of PS films. It was observed that MPS-grafted silica nanoparticles might yield hydrophobic functionalized methcrylate groups on the surface of silica, resulting in a decreased surface energy.