M. Logar, et al. Polyelectrolyte multitayer template assisted in-situ synthesis... Contemporary Materials, I–1 (2010) Page 4 of 18 Original scientific papers UDK 530.145:546.26 DOI: 10.5767/anurs.cmat.100101.en.004L POLYELECTROLYTE MULTILAYER TEMPLATE ASSISTED IN-SITU SYNTHESIS OF THE INORGANIC NANOSTRUCTURES M. Logar, 1* B. Jančar, 1 A. Rečnik 2 , D. Suvorov 1 1 Advanced Materials Department, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia 2 Nanostructured Materials Department, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia Apstract: Multilayers formed from weak polyions of polyallylamine (PAH) and polyacrylic acid (PAA), possessing ion-exchangeable carboxylic groups were used to bind the metal cations within the film. By subsequent wet chemical reaction process of the incor- porated metal ions, pure zinc sulfide (ZnS) with a narrow size distribution was formed wit- hin the PEMs. The size and concentration of the inorganic nanoparticles in polyion matrix were controlled by the concentration of metal – binding carboxylic acid groups as determi- ned by the multilayer assembly pH. Furthermore, the metal cation loading and reaction met- hodology could be repeatedly cycled to increase the size and volume density of the nano- particles. Furthermore, the polyelectrolyte multilayer films were used as templates for the ceramic (TiO 2 ) thin film fabrication with a modified sol-gel reaction. Since the multilayer assembly is performed from the polyion aqueous solutions, the multilayers contain some water that, after infiltration of the organometallic precursor, enables in-situ reaction of hydrolysis and condensation reaction. After calcination, nanocrystalline TiO 2 thin films with thickness, controllable by the number of the polyion layers in the matrix, were formed. With the in-situ synthesis approach of inorganic nanstructures in polyelectrolyte multilayer matrix, the ability of obtaining the control over the film thickness and size of the inorganic particles has enabled the tuning of the optical properties of as fabricated inorganic-organic composite films, as well as nanocrystalline ceramic films. Keywords: Polyelectrolyte multilayer, in-situ synthesis, ZnS nanoparticles, Nano- crystalline TiO 2 film. 1. INTRODUCTION Thin film nanocomposites consisting of inor- ganic matter embedded within a soft polymeric m- atrix on the nanometer scale offer unique properties with potential application in the optoelectronics and photonics. Inorganic nano-sized particles have been investigated intensely due to their potentially intere- sting optical properties, steaming from the quantum confinement effect and their surface characteristics. By approaching to the nano-meter regime, due to the size dependency of the particle band gap energy and increase in the surface-to-volume ratio, a careful control over the size and surface state density of the inorganic particles is essential in order to obtain the desired physical properties [1]. By embedding the inorganic nanoparticles within a suitable matrix, po- ssible control over the particle surface states and si- ze-distribution yield the ability to control their phy- sical properties thus making such inorganic-organic nanostructured materials more attractive for their po- tential application in different areas [2–3]. Recently, organized supramolecular assembli- es, formed by the layer-by-layer (LbL) self-assembly of polyelectrolytes, have been extensively utilized as organic nanostructured templates for the inorganic- organic nanocomposite film formation [4]. With this method, the sequential adsorption of oppositely charged polyelectrolytes, based on the electrostatic interactions between the two components, yield the multilayer network structure, where, by varying the number of the adsorbed polyion layers, the control over its thickness in nanometer scale is obtained. In the assembly of the polyion chains, their molecular organizations lead to the formation of voids within the multilayer template, which can serve as sites for * Corresponding author: manca.logar@ijs.si