Construction of Renewable Superhydrophobic Surfaces via Thermally Induced Phase Separation and Mechanical Peeling

Abstract

We report a simple preparation method of a renewable superhydrophobic surface by thermally induced phase separation (TIPS) and mechanical peeling. Porous polyvinylidene fluoride (PVDF) membranes with hierarchical structures were prepared by a TIPS process under different cooling conditions, which were confirmed by scanning electron microscopy and mercury intrusion porosimetry. After peeling off the top layer, rough structures with hundreds of nanometers to several microns were obtained. A digital microscopy determines that the surface roughness of peeled PVDF membranes is much higher than that of the original PVDF membrane, which is important to obtain the superhydrophobicity. Water contact angle and sliding angle measurements demonstrate that the peeled membrane surfaces display superhydrophobicity with a high contact angle (152°) and a low sliding angle (7.2°). Moreover, the superhydrophobicity can be easily recovered for many times by a simple mechanical peeling, identical to the original superhydrophobicity. This simple preparation method is low cost, and suitable for large-scale industrialization, which may offer more opportunities for practical applications.