Composite films of polycations and TiO2 nanoparticles with photoinduced superhydrophilicity

We apply herein the reactive layer-by-layer (LBL) spray deposition of a polycation (polyethyleneimine, PEI) and a water soluble initiator of titanium dioxide [Ti(IV) bis(ammoniumlactato)dihydroxide, TiBisLac] to produce thin hybrid films containing PEI and nearly monodisperse TiO2 anatase nanoparticles. The thickness of these coatings can be finely adjusted by either changing the number of deposition steps or the TiBisLac concentration. These films display intense absorption in the UV range and nearly full transparency above 365 nm and they also display photoinduced superhydrophilicity. These coatings can be produced either by reactive LBL spray deposition or reactive LBL dipping and may offer a wide range of applications from biology, as antibacterial coatings, to photoactive materials. (c) 2008 Elsevier Inc. All rights reserved.