Photochromic and photocatalytic inorganic-organic multilayer films based on polyoxometalates and poly(ethylenimine)

Original photochromic and photocatalytic multilayer films are produced by the polyoxometalate (POM) SiW12O404- and poly(ethylenimine), via the layer-by-layer (LbL) self-assembly method. Irradiation with ultraviolet-near visible light of this composite material causes reduction to POM (SiW12O405-), while the films acquire the characteristic blue color of reduced POM. Oxygen plays a great part in the gradual reoxidation of the coated POM, resulting in the reversible photochromism of the films. The development process, the composition, the morphology of the surface and the photochromic properties of the multilayer films were studied by UV-vis spectroscopy, FTIR and atomic force microscopy. Preliminary results have shown these films to demonstrate interesting photocatalytic properties.