Superhydrophobic Composite Coatings From Carbon Nanotubes

The "lotus effect" has been good understood after the extensive study on the morphology of lotus leaves, and artificial superhydrophobic coatings with self-cleaning property, have been prepared. Multi-functional composite coatings combining transparency and conductivity with superhydrophobicity have received a considerable amount of attention because they can be used as smart windows, deicing materials, waterproof electronic devices, transparent electrodes, optoelectronic devices, etc. Multi-functional superhydrophobic coatings have already become one of the hot topics of the research.In the present study, we used hot press method and spraying method to prepare multi-functional superhydrophobic coatings. Three types of superhydrophobic composite coatings were studied.(1) MWNTs/polymer conductive superhydrophobic composite coatings had been prepared using hot press method for the first time. This method is applicable for thermoplastic polymers, thermoset polymers and substrates covered with polymers. The composite coatings own a sheet resistance of 103Ω/sq, water contact angle (WCA) above 150°and sliding angle (SA) below 5°. Pressing time influences the properties of the composite coatings on the surface of high density polyethylene. The relationship between the surface morphology and conductivity, hydrophobicity was studied. The deicing applications of those composite coatings were also studied.(2) The MWNTs modified by a polysoap (SMI) and tetraethyl orthosilicate (TEOS) were used to prepare the superhydrophobic coatings by spraying method. The Silica/SMI/MWNTs composite coatings exhibit a WCA above 160°, SA below 2°, and a transparence of 78%. The influence of surface density on the hydrophobicity and transparency was studied. The surface morphology of the modified MWNTs and the hydrophobicity of the corresponding coatings were also studied. The evolution of the air bubbles formed on the superhydrophobic coating after being immersed in water was also studied.(3) Silica sols (SiO2) and hydroxyl multiwalled carbon nanotubes (CNT-OH) were used to prepare the superhydrophobic coatings with a WCA above 160°, SA below 2°through spraying method. The conductivity, transparency, superhydrophobicity, durability were studied.