Synthesis and characterization of polystyrene-Zn-TiO2 nano-composites based superhydrophobic self-cleaning coating

Abstract

Self-cleaning coatings are increasingly recognized as sustainable solutions for surface maintenance in diverse applications, minimizing environmental impact and operational expenses, especially titanium dioxide (TiO₂) based coatings. Photocatalytic activities of TiO₂ removed contaminants deposited on the glass surfaces. However, the efficacy of photocatalysis of TiO₂ needs to be improved due to its wide band gap nature. Zn doping reduced the optical bandgap, which facilitated charge transfer and introduced novel electronic states. In this context, Zn-doped TiO₂ nanoparticles have been synthesized using the sol-gel method to obtain a reduced band gap and enhance self-cleaning performance. The range of doping concentrations was 0–3.5 % mol. The nanoparticles were dispersed in a polystyrene containing silicone oil matrix to fabricate the self-cleaning coating, which was spin-coated onto a glass substrate. To improve the adhesion to the glass substrate, polymer is specifically utilized in the coating solution. The structural, morphological, and optical properties were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–visible spectroscopy (UV–Vis). Finally, dust removal, antifog analysis and contact angle measurements were analyzed to assess the self-cleaning ability. XRD analysis showed that Zn doping significantly altered crystallite sizes of TiO₂ nanoparticles by consisting of anatase phase. From the SEM, the average particle size of undoped and 3.5 % Zn doped TiO₂ was 18 nm and 21 nm respectively. The band gap of TiO₂ gradually decreased from 3.20 eV to 1.65 eV due to 3.5 % Zn doping which enhanced the ability to absorb visible light and increased its photocatalytic activity. Hydrophobicity of the coating was drastically enhanced as a consequence of Zn doping. The highest water contact angle was 148° for 3.5 % Zn doped TiO₂ nanocomposite. The nanocomposites have better dust removal and anti-fogging capabilities than undoped TiO2. The findings indicate that the coating has prospective industrial applications as a self-cleaning coating.