Figure 6 UV–vis spectroscopy of the green multilayer films for different number of bilayers (10, 20, 30 and 40) and photographs of the coatings. In order Nutlin-3a purchase to understand the incorporation of the multicolorAgNPs inside the LbL assembly, the position of the absorption bands with their corresponding intensities and the aspect in coloration of the final films have been analyzed. However, to create a template of well-defined coloration, the thickness of the resulting films to incorporate the AgNPs plays a key role, which

is perfectly controlled by two factors, the pH value of the polyelectrolyte solutions (PAH and PAA-AgNPs) and the number of bilayers deposited onto glass slides [47, 48]. When the pH of the dipping solutions is 7.5, both PAH and PAA-AgNPs

are adsorbed as fully charged polyelectrolytes and very thin films are obtained. For a total of 40 bilayers, the average thickness is varied from 185 nm (PAH/PAA-AgNPs violet coating), 223 nm (PAH/PAA-AgNPs orange coating) to 293 nm (PAH/PAA-AgNPs green coating). In Figure  7, the evolution of the thickness for different number of bilayers (10, 20, 30 and 40, respectively) with their error bars in this pH regime (7.5) is shown. According to these thickness results, it is possible to appreciate that PAH/PAA-AgNPs with a light orange coloration instead of clearly green coloration is due to the higher incorporation of AgNPs with nanometric spherical size instead of metal clusters selleck compound into the film for a coating of 40 bilayers. Figure 7 Evolution of thickness of the PAH/PAA-AgNPs

multilayer assemblies (violet, green, orange) for different number of bilayers. Obviously, in all the cases of study, the thickness and the resultant color formation depends basically on surface charge of both ionized PAH/PAA polymeric chains, the number of bilayers deposited, the number of the AgNPs incorporated and the distribution of them with a specific shape during the fabrication process. In order to show the aspect of the thin films after LbL fabrication process, AFM click here images of 40 bilayers [PAH/PAA-AgNPs] at pH 7.5 reveal that the morphologies of the thin films were homogeneous, very slight porous surfaces with an average roughness Selleckchem 5FU (rms) of 12.9 nm (violet coloration), 16.7 nm (green coloration) and 18.6 nm (orange coloration). In all the cases, the polymeric chains of the weak polyelectrolytes (PAH and PAA) are predominant in the outer surface and the AgNPs are embedded inside the polymeric films. In order to show the presence of these AgNPs in the LbL assembly, a thermal treatment of the films was necessary with the idea of evaporating the polymeric chains (PAH and PAA, respectively) and so, the contribution of the AgNPs can be appreciated when the fabrication process is performed. In Figure  8, AFM images corresponding to 10, 20, 30 and 40 bilayers of PAH/PAA-AgNPs (violet coloration) after a thermal treatment of 450°C are shown.