Enhanced persistence of natural super-hydrophilicity in TiO2–SiO2 composite thin films deposited via a sol–gel route

TiO2–SiO2 composite thin films have been deposited via a sol–gel route. Their morphological, physico-chemical, and wettability properties have been studied. It is shown that composite films exhibit an unexpected natural super-hydrophilicity that persists with time in the absence of any UV light exposure. Depending on the experimental conditions, this natural super-hydrophilicity can persist for at least eight weeks in ambient aging conditions. Such a property allows envisaging applications to surfaces with enhanced cleanability in atmospheres where UV light is not permanently present. It is shown that natural carbon contamination does not preponderantly influence the persistent super-hydrophilicity of TiO2–SiO2 composite films. This property is then studied and discussed with respect to the film morphological and physico-chemical properties.