Preparation And Research On TiO₂-AgBr Reversible Photochromic Material

Recently, reversible photochromic material has wide concerntration by researchers at home and abroad because of practical value. In this paper, reversible photochromism materials were prepared by the sol-gel method and sol-emulsion-gel method, and studied the structure, performance and photochromic mechanism. Expoxy photochromatic coating was prepared using photochromic material as functional filler and studied the comprehensive properties.Hydrolysis reaction occurs in butyl titanate when using acetic acid as reaction medium and HCl to control pH. We studied the influence of particle size of TiO₂ sol particles by dosage of anhydrous ethanol, deionized water, butyl titanate, ice acetic acid, pH and other factors. Based on these, TiO₂-AgBr chromism materials were prepared by sol-gel method and sol-emulsion-gel method. The results showed that: particle size of TiO₂ sol particles using sol-emulsion-gel method decreased from 876 nm to 354 nm when CTAB concentration was 0.137 mo L/L.The photochromic properties of TiO₂-AgBr samples were characterized by UV visible absorption spectrometer（Uv-Vis）, structure was analyzed through X-ray diffractometer（XRD）, infrared spectrum（FT-IR）, comprehensive thermal analysis（TG/DSC） and scanning electron microscope（SEM）. The reaction model and photochromic mechanism of TiO₂-AgBr was discussed. The results indicated that: TiO₂-AgBr samples by two preparation methods both had photochromic property, the TiO₂-AgBr using sol-emulsion-gel preparation method had obvious photochromic phenomenon and reversibility, high crystallinity and lower weight loss rate by TG/DSC.Expoxy photochromatic coating was prepared through adding TiO₂-AgBr with better performance as functional filler. The results showed that: expoxy coating changed color under the UV light, this change had reversibility from yellow to khaki. The performance of coating was excellent when w（660A）=30%, w（hydroxy silicone oil）=0.8%, w（KH550）=0.3%, w（amorphous silica）=1%, w（TiO₂-AgBr）=0.5%, w（ethylenediamine）=15%（relative to the quality of E44）.