Synthesis and characterization of superhydrophobic surfaces prepared from silica and alumina nanoparticles on a polyurethane polymer matrix

Abstract

An economical approach to synthesize superhydrophobic surfaces with silica and alumina nanoparticles on a polyurethane-based paint is presented. The surfaces have been prepared by spraying functionalized nanoparticles on the partially cured polymer matrix, and they have been characterized with Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy and water contact angle measurements. Results show that the gel point is reached 26 min after the application of the paint when it is cured at 70 degrees C. At that moment, rather than submerging into the paint, the sprayed nanoparticles remain partially exposed at the surface. Following this approach, we have found that, for samples including 0.5 wt% of polydimethylsiloxane-functionalized nanoparticles, water droplets show contact angles higher than 150 degrees, have a negligible attachment to the substrate and easily roll off the substrates. The application method is fast and scalable to relatively wide areas. Also, nanoparticles are located only at the surface, thus reducing manufacturing costs.