Preparation and XPS study of X-ray photochromic transparent BiOI/nylon11 composite film

Nylon11 film immersed in BiI3-ethanol solution was used for in situ generation of transparent BiOI/nylon11 X-ray photochromic composite materials via integration of the hydrolyzate (BiOI) of BiI3 into nylon11. The obtained BiOI/nylon11 composite film shows a reversible photochromic effect, changing the color from orange-red to brownish black under soft X-ray irradiation and back to orange-red after air exposure. X-ray photoelectron spectroscopy (XPS) results show that the oxidation state of Bi atoms in BiOI/nylon11 composite film does not change before and after changing the color. Angle-resolved XPS analysis reveals that BiOI in nylon11 film is well distributed within an infiltration depth of about 10 nm. The source of the X-ray photochromic effect for transparent BiOI/nylon11 composite film may be related to oxygen as well as the interaction between BiOI and the amide groups. The oxygen AT% in the composite film decreases with increasing X-ray irradiation time. The present method for preparing transparent BiOI/nylon11 X-ray photochromic composite materials is facile and low cost. The X-ray photochromic effect has potential applications in some technology fields. For example, it can be used to create temporary patterning in a colored composite material surface.