화학공학소재연구정보센터
Langmuir, Vol.18, No.3, 904-910, 2002
Electrostatic interactions between polyelectrolytes and a titania precursor: Thin film and solution studies
A facile approach, based on the polyelectrolyte-mediated electrostatic adsorption of a water-soluble titania precursor, titanium (IV) bis (ammonium lactato) dihydroxide (TALH), is presented for the formation of multilayered thin films of defined thickness and composition. The thin films were formed by the alternate deposition of TALH and positively charged polyelectrolyte [poly (diallyldimethylammonium chloride), PDADMAC, poly (allylamine hydrochloride), PAH, and chitosan, CH] utilizing electrostatic interactions for film formation. Layer-by-layer film growth was monitored by UV-vis spectrophotometry, ellipsometry, and by a quartz crystal microbalance (QCM). The UV-vis, ellipsometric, and QCM data all showed that a uniform amount of TALH was deposited with each alternate deposition cycle of polyelectrolyte and TALH, indicating that TALH binds to positively charged polyelectrolytes. Using PDADMAC/TALH as a model system, the influence of drying on multilayer film formation was examined by QCM. These experiments showed that water-equilibrated multilayers facilitated the binding of TALH to PDADMAC. The electrostatic nature of the binding between TALH and positively charged polyelectrolytes was confirmed by fluorescence studies in aqueous solution: Removal of the anionic probe, pyrenetetrasulfonic acid (4-PSA), precomplexed to PDADMAC in aqueous solution, was observed upon the addition of TALH PDADMAC/TALH multilayers were also constructed on colloid particles in order to gain insight into the binding behavior between the deposited species. The results suggest that multilayer film formation is facilitated via the deposition of oligomeric species of TALH. The approach presented here may be exploited for the fabrication of novel advanced titania-based materials (e.g. thin films, porous structures, and composite colloids).