Enhanced antimicrobial coating on cotton and its impact on UV protection and physical characteristics

This research intends to enhance the antimicrobial activity of cotton fabrics coated with metallized TiO2-based colloids through integrating noble metals (Ag, Au) and silica in the synthesis process. Colloids were synthesized through a low-temperature sol-gel method and applied to the surface of fabrics at ambient temperature. Four molar ratios of metal to TiO2 (0.01, 0.1, 0.5 and 1%) were used in the synthesis process of colloids to elucidate the impacts of metal type and concentration on the antimicrobial activity of fabrics. The antimicrobial property of coated fabrics was studied through monitoring the growth reduction rate of Escherichia coli (E. coli) bacterium in dark. The UV protection property of coated fabrics was analyzed based on the ultraviolet protection factor (UPF) and UV transmittance rates of fabrics. Moreover, the impact of coating process on the mechanical characteristics of fabrics was examined based on changes in fabric tensile strength and air permeability. The surface morphology and elemental composition of coated fabrics were characterized using SEM images and EDS analysis, respectively. It was observed that the presence of noble metals significantly enhanced the antimicrobial property of fabrics particularly for samples coated with Ag-modified colloids. Also, the presence of metals and silica showed positive and negative impacts on UPF values of fabrics, respectively. While the fabrics' tensile strength improved, the air permeability decreased to some extent after coating. The role of influencing parameters such as the type and concentration of metals, the presence of silica, and the associated mechanisms were discussed.