Study on the Wettability and Optical Properties of Polydimethylsiloxane-SiO2 Nano-composite Surfaces

In this paper, the effects of different weight percentages of silica nano-particles on the wettability and optical properties of polymer based surfaces were investigated. The Polydimethylsiloxane (PDMS)-SiO2 nano-composites containing 0.5, 1, 2, 3 and 4 wt% silica were prepared and coated on the fabric surfaces by immersion technique at the ambient conditions. Then, the characterization of nano-composite coated samples was carried out by water contact angle technique, scanning electron and atomic force microscopes and diffuse reflectance spectroscopy. It was found that increasing the silica content caused to increase the water contact angle of sample to 158° which results in an improvement in the water repellency property. This can be due to the aggregation of silica nano-particles which led to higher surface roughness of sample. The AFM and SEM images validated the results of surface roughness. However, Silica-PDMS composite coated sample exhibited a lower transmittance value (57%) in comparison to the uncoated sample (90%). This can be ascribed to the light scattering by silica nano-particles.