title: Reactive layer-by-layer deposition of poly(ethylene imine) and a precursor of TiO2: influence of the sodium chloride concentration on the film growth, interaction with hexacyanoferrate anions, and particle distribution in the film.
abstract: Films prepared according to a layer-by-layer (LBL) manner find increasing importance in many applications such as coatings with dedicated optical or electronic properties, particularly when including nanomaterials. An alternative way to prepare such hybrid layer-by-layer coatings is to perform sol-gel chemistry in a layer-by-layer manner. In this article, we highlight the importance of the NaCl concentration as a parameter to control the growth as well as the properties of LBL films made from poly(ethylene imine) as the organic counterpart and titanium IV (bisammoniumlactato)dihydroxyde ([Ti(lac)(2)(OH)(2)](2-)) as the precursor of TiO(2). An increase in the sodium chloride concentration leads to the faster growth of the film and to a decrease in the number of hexacyanoferrate anions remaining in the film after a buffer rinse. This may be due to a progressive increase in the fraction of negatively charged TiO(2) as suggested by transmission electron microscopy. In the presence of 0.5 M NaCl, the fraction of TiO(2) is close to 60% in mass. As a surprising finding, the films produced from 0.15 M NaCl are not homogeneously filled with TiO(2) even if the film is produced in an LBL fashion. The increased concentration of TiO(2) at the film-solution interface could constitute a barrier for the incorporation of the negatively charged redox probe.
authors: Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche 977, 11 rue Humann, 67085 Strasbourg, Cédex, France.
authors: Nadia
authors: N
authors: Ladhari
authors: Christian
authors: C
authors: Ringwald
authors: Ovidiu
authors: O
authors: Ersen
authors: Ileana
authors: I
authors: Florea
authors: Joseph
authors: J
authors: Hemmerlé
authors: Vincent
authors: V
authors: Ball