Overshoots of adsorption kinetics during layer-by-layer polyelectrolyte film growth: role of counterions

International audienc

Particle Velocities near and along the Electrode during Electrophoretic Deposition: Influence of Surfactant Counter-Ions

International audienceResearch into the micro-nanostructured coatings process has made a variety of new applications available. Electrophoretic deposition (EPD) is an efficient and attractive technique to produce coated materials. Therefore the understanding of the formation and growth mechanism of the coating process continues to be investigated. In this study, a home-made EPD laminar flow cell was used for in-situ investigation of the particle velocity and deposition of micronic particles on a cathode. Monodisperse polystyrene latex particles were functionalized with cationic surfactants: cetyltrimethyl ammonium bromide (CTAB) or cetyltrimethyl ammonium chloride (CTAC). The tangential velocity of the particles when they migrated to the electrode, the approach angle and the tangential velocity along the electrode were measured under a DC electric field. From the values of the velocities, the particle-electrode distance was evaluated in CTAB and CTAC solutions. The electrophoretic velocity was calculated from the electrophoretic mobility of the particles and the electric field applied to the particles. All these parameters depend on the type of surfactant counter-ions and influence the growth of the coating. Dense structures were obtained in CTAB solution while open structures were observed in CTAC solution

Fabrication of Ni(OH)2 / alginate composite films via layer-by-layer method

International audienc

A new approach to determine the mean thickness and refractive index of polyelectrolyte multilayer using optical reflectometry

International audienc

Electrophoretic deposition of nickel hydroxide particles to shape nickel oxide Films

International audienc

In situ investigations of electrogenerated polybithiophene film growth on indium tin oxide substrate using optical fixed-angle reflectometry

International audienc

Preparation of conductive PDDA/(PEDOT:PSS) multilayer thin film: Influence of polyelectrolyte solution composition

International audienceSelf-assembled multilayer films made of PEDOT:PSS poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)and PDDA poly(diallyldimethylammonium chloride) were prepared using layer-by-layer method.In order to modify the growth regime of the multilayer, to fabricate an electrical conductive film and tocontrol its thickness, the effects of pH, type of electrolyte, ionic strength and polyelectrolyte concentrationwere investigated. Optical reflectometry measurements show that the pH of the solutions has noeffect on the film growth while the adsorbed amount increases more rapidly when BaCl2 is used insteadof NaCl as electrolyte. An increase in the ionic strength (with NaCl) induces a change in the growth regimefrom a linear to an exponential one at low polyelectrolyte concentration. As UV–vis measurementsindicate, no decomplexation of PEDOT was recorded after film preparation. With polyelectrolyte concentrationbelow 1 g L1, no conductive films were obtained even if 50 bilayers were deposited. A conductivefilm was prepared with a polyelectrolyte concentration of 1 g L1 and the measured conductivity was0.3 S m1. A slight increase in conductivity was recorded when BaCl2 was used probably due to amodification of the film structure

Electrophoretic deposition of composite silica/latex particles onto gold substrate and polythiophene-based films

International audienc

Stability and cathodic electrophoretic deposition of polystyrene particles pre-coated with chitosan-alginate multilayer

International audienceThe electrophoretic deposition of particles functionalized with self-assembled biocompatible polymers on stainless steel was investigated with the objective to develop new bioactive coatings which may be used in different applications such as opto-electronics, biosensors or medical applications. Alternate layers of chitosan and alginate were first adsorbed on monodispersed polystyrene colloidal particles using the layer-by-layer technique. The build-up of the polyelectrolyte films was followed by electrophoretic mobility measurements. The stability of the multilayered structure was then investigated after each adsorption step by following the change of particle zeta potential consecutive to the exposure of diluted suspensions at pH and salt conditions different from those used during the adsorption procedure. Therefore, the best experimental conditions (pH, number of layers, particle concentration) were determined in order to maintain a good stability of the preformed chitosan/alginate films after dilution for the electrophoretic deposition experiments. In these conditions, zeta potential of the core-shell particles was kept constant when exposed under an electric field which was a key factor for successful electrophoretic deposition of core-shell particles on steel surface with high coverage. Moreover the feature of final deposits was strongly correlated to the stability of the multilayer film