Enhancement of Photochromism in Poly(Vinyl Alcohol)–Phosphotungstic Acid Nanocomposites Using a Low-Molecular-Weight Alcohol Additive

Poly(vinyl alcohol) (PVA)–phosphotungstic acid (PTA) nanocomposite films were prepared from aqueous solutions with added ethylene glycol (EG), which is a plasticizer for PVA and contains OH groups, capable of being electron donors in the photoreduction of PTA. Spectroscopic studies have shown that the addition of EG significantly enhances the photochromic properties of the resultant nanocomposites due to photoinduced electron transfer from the organic matrix of the nanocomposite to PTA molecules.