Solvent-free zirconia nanofluids/silica single-layer multifunctional hybrid coatings

Novel single-layer multifunctional coatings simultaneously exhibiting improved optical transparency, hydrophobicity, mechanical strength, anti-wear property and environmental resistance on the polycarbonate (PC) substrates are developed by assembling silica nanoparticles with solvent-free zirconia nanofluids. Various characterization techniques, e.g., contact angle, surface morphology, surface hardness, adhesion, abrasion, chemical endurance and UV aging tests, were employed to evaluate the prepared hybrid coatings. The results indicated that zirconia nanofluids provide the hybrid coatings with excellent comprehensive properties. Optical transmission of 96% in the visible region of the spectrum was realized in optimized coatings. The hydrophobicity of the coated films was improved obviously due to lowered surface energy and formation of well-defined nanometer-sized structures on the surface. The coated PC films exhibited a surface hardness of 5H, first grade adhesive strength, prominent wear resistant performance and a good stability against acidic erosion and UV irradiation. Since no high-temperature post treatment of the coatings is required to render them high hardness, the present method is relatively simple and inexpensive, particularly for large-area polymer substrates. These results indicate that the fabricated hybrid coatings have great potential to upgrade the efficiency of solar energy related devices. (C) 2014 Elsevier B.V. All rights reserved.