Superhydrophobic polytetrafluoroethylene surfaces by spray coating on porous and continuous substrates

Abstract

We study the preparation of superhydrophobic polytetrafluoroethylene (PTFE) coating by a spraying method with copper mesh and aluminum plate substrates. The hydrophobicity and toughness of the resulting surfaces are investigated using water contact angles, sliding angles, rubbing tests, and impact experiments. The heat treatment is found to be the key to adjusting the microstructure as well as the wettability. Sufficient heat accumulation at 230 °C through 50 min sintering gives rise to a hierarchical structure characterised by micro spheres with lots of nanopores on their surfaces, leading to excellent water repellence proved by the large contact angle, and small sliding angle, and the complete water drop rebounce. Insufficient heat accumulation with less than 20 min sintering at 230 °C results in micro spheres without nanopores; the resulting surface presents weak water repellence in all the property tests. In addition, the porous substrate of copper mesh is proved feasible for the spraying preparation of a tough superhydrophobic surface, although it is not as good as the continuous substrate of aluminum plates.