Titania Opal and Inverse Opal Structures via Templating Polyelectrolyte Multilayer Coated Polystyrene Spheres

We report the construction of titania contained opal and inverse opal structures by using colloidal crystals as templates which were self assembled from poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA) multilayer film coated polystyrene (PS) particles. By infiltrating a titania precursor titanium (IV) bis (ammonium lactato) dihydroxide (TALH) into the polyelectrolyte (PE) multilayer film followed by calcination at different temperatures, PE/TiO2 composite opal or inverse opal structures were obtained. The thickness of the titania coating on colloidal crystals or the wall thickness of titania inverse opals could be controlled by varying the coating thickness of the PE film on PS particles during the layer-by-layer (LbL) deposition process. The crystalline phase of titania inverse opals was determined by the heating temperature. However, titania inverse opals with pure rutile phase lost their ordered structures due to the formation of large rigid rutile titania crystals during the phase transfer process. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), reflectance spectroscopy and X-ray diffraction were employed to characterize the formed structures and titania crystal phases.