Extruded expanded polystyrene sheets coated by TiO ₂ as new photocatalytic materials for foodstuffs packaging

Nanostructured, photoactive anatase TiO ₂ sol prepared under very mild conditions using titanium tetraisopropoxide as the precursor is used to functionalise extruded expanded polystyrene (XPS) sheets by spray-coating resulting in stable and active materials functionalised by TiO ₂ nanoparticles. Photocatalytic tests of these sheets performed in a batch reactor in gas-solid system under UV irradiation show their successful activity in degrading probe molecules (2-propanol, trimethylamine and ethene). Raman spectra ensure the deposition of TiO ₂ as crystalline anatase phase on the polymer surface. The presence of TiO ₂ with respect to polymer surface can be observed in SEM images coupled to EDAX mapping allowing to monitor the surface morphology and the distribution of TiO ₂ particles. Finally thermoforming of these sheets in industrial standard equipment leads to useful containers for foodstuffs.