Spectral and physical properties organo-silica coated photochromic poly-ethylene terephthalate (PET) fabrics

In this study, photochromic fabrics were prepared by incorporating the spirooxazine derivative of 5-chloro-1,3-dyhydro-1,3,3-trimethylspiro[2H-indole-2,3′-[3H]-naphth [2,1-b] [1,4] oxazine on the polyethylene terephthalate (PET) fabric through a sol-gel coating process. The treated fabrics showed good photochromic response under UV irradiation. In this work, three types of silane were used as the silica precursor and the resultant coatings showed a significant difference in their photochromic response such as Kubelka–Munk function (K/S), change in optical density (ΔOD) rate constant and half-life. The coated fabric shows two different absorption maxima and however it confirms that there is strong influence on the type of silane. The functional group of uncoated and sol-gel coated fabrics are analyzed by ATR-FTIR. The type of the silane also influences the physical properties of the coated fabrics. The surface characteristics were analyzed by scanning electron microscope (SEM) and laser scanning confocal microscope (LSCM), which showed significant changes in the surface micro-roughness after coating.