Ultrasound-induced change of microstructure and photochromic properties of polyacrylamide thin films containing a polyoxometalate

Novel photochromic nanocomposite thin films were prepared by entrapping polyoxometalate in a polyacrylamide matrix via the ultrasound technique. The ultrasound irradiation has a great effect on the microstructure and photochromic properties of the hybrid films. The polyoxometalate nanoparticles are finely dispersed in the polymer matrix after ultrasound treatment, instead of agglomeration in the unirradiated film with ultrasound. Consequently, the photochromic behaviors of the hybrid films can be controlled from irreversible heteropolybrown to reversible heteropolyblue by ultrasound. The influence of ultrasound on microstructure and photochromic properties is due to the sonochemical controlling interfacial interactions in the hybrid system.