Through structure design, 3D printing enables the fabrication of mechanically durable superhydrophobic membranes with an ordered porous structure for oil–water separation.
We herein provide an effective method to fabricate a transparent superamphiphobic coating with superhydrophobicity and near-superoleophobicity, the finished coating also shows improved stability under various measurements. To do this, a transparent superhydrophobic coating was first prepared with polydimethylsiloxane (PDMS) and hydrophobic silicon dioxide (SiO 2 ) nanoparticles. Then the coating was sintered to degrade the PDMS into SiO 2 before it was further oxidized into silanol (Si-OH). Finally, the coating was treated with 1H, 1H, 2H, 2H-Perfluorooctyl-trichlorosilane (PFTS). The PFTS treated coating shows transparency, superhydrophobicity with a water contact angle of 152.7 AE 2.1 and near-superoleophobicity with a diiodomethane contact angle of 140.7 AE 3.2 . The droplets of water and diiodomethane can simultaneously slide off the surface with a sliding angle of less than 6 . Moreover, the PFTS treated coating shows a higher stability than the PDMS/SiO 2 coating fabricated by spin coating under various environmental conditions. The PFTS treated coating also shows quite good stability under high temperature environment. The superamphiphobic properties, transparency and improved stability of the PFTS treated coating are systemically discussed and the results show that the finished coating may be appropriate for many outdoor applications.
Thin films of an amorphous polymer, polystyrene (PS), and a crystalline polymer, poly(ε-caprolactone) (PCL), blend were prepared by spin coating a toluene solution. Surface chemical compositions of the blend films were measured by X-ray photoelectron spectroscopy (XPS), and the surface and interface topographical changes were followed by atomic force microscopy (AFM). By changing the PS concentration and keeping the PCL concentration of the solution at 1 wt %, a great variety of morphologies were constructed. The results show that the morphology of the blend films can be divided into three regions with increasing PS concentration. In region I, PS island domains are embedded in PCL crystals when the PS concentration is lower than 0.3 wt % and the size of the PS island increases with increasing PS concentration. In region II, holes with different sizes surrounded by a low rim are obtained when the concentration of PS is between 0.35 and 0.5 wt %. After selectively washing the PS domains, we studied the interface morphology of PS/PCL and found that the upper PS-rich layer extended into the bottom PCL layer, forming a trench surrounding the holes. In region III, an enriched two-layer structure with the PS-rich layer on top of the blend films and the PCL-rich crystal layer underneath is obtained when the concentration of PS is higher than 0.5 wt %. Last, the formation mechanism of the different surface and interface morphologies is further discussed in terms of the vertical phase separation to a layered structure, followed by liquid-liquid dewetting and crystallization processes during spin coating.
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