Dynamically modifiable wettability comparisons of the hydrophilic and hydrophobic substrates coated with F/TiO2 hybrid sol by UV irradiation

Abstract

To prepare a functional surface with dynamically modifiable wettability on cotton and polyester fabrics by hybrid coating, the F/TiO2 hybrid sol were synthetized with tetrabutyl titanate and fluoride silane coupling agent via sol–gel technology. The anatase component in F/TiO2 hybrid powder was mixed with rutile component from XRD, and the crystal component was unchanged in UV light and dark store condition. The switchable wettability of the fabric was assessed by contact angle in different conditions and time. The maximum contact angles of cotton and polyester fabrics coated with F/TiO2 hybrid sol were 141.8° and 136.1°, respectively, and through UV irradiation, the minimum contact angles of cotton and polyester fabrics coated with F/TiO2 hybrid sol were both 0°, respectively. Within storing in dark, the contact angles nearly completely reverted. The switchable cycle of the cotton was 84h, while the switchable cycle of the polyester was 168h. From AFM and fabric constructions (porosity, permeability and roughness) analysis, the fiber morphology had more effect on the contact angle than the fabric constructions. The F/TiO2 hybrid powder and the coated fabric floated on water for their excellent hydrophobicity, and the samples deposited at the bottom of water as the wettability of coated fabric increased via UV irradiation. The irradiated samples were placed in dark, and the samples floated on water again. The water diffusion and permeable capacities further confirmed the dynamically modifiable wettability. The water diffusivity and permeable capacity further confirmed the excellent switchable wettability of coated fabrics by F/TiO2 hybrid sol through UV irradiation or storage in dark.