Imparting anti-fog properties to polycarbonate sheet by simultaneous use of gliding arc plasma and hydrophilic polymer composite coating

Abstract

Polycarbonate is one the polymers widely used in transparent products. However, fog formation on PC surfaces seriously reduces the transparency and visibility of these products. Therefore, various strategies have been used to impart anti-fog properties to PC surfaces. In this research, a hybrid strategy, i.e., a combination of plasma treatment and coating a hydrophilic layer, was used to improve the anti-fog properties of PC sheets. Surface treatment was performed by gliding arc plasma and surface coating was done by dip-coating of polyvinyl alcohol/silica dispersion. Morphological evaluation of the PC surfaces showed that applying the hybrid strategy improved the dispersion of silica nanoparticles on the surface and reduced the surface roughness. The roughness of the plasma treated-PVA/silica coated sample was reduced by 68% and 56% compared to the plasma treated and PVA/silica coated samples, respectively. The evaluation of anti-fog properties revealed that the sample treated with the hybrid strategy retained its hydrophilicity and anti-fog properties better, while the plasma treated and PVA/silica coated samples largely lost their hydrophilicity and anti-fog properties with time. According to the water droplet condensation assay, on the plasma treated PVA/silica coated surface, the droplet formation time was reduced by only 11% in the seventh cycle compared to the first cycle, corroborating the highest durability of the anti-fog properties in this sample. In summary, the PC sheets subjected to the combined strategy of plasma modification and PVA/silica coating showed superior and longer-lasting anti-fog properties.