Events / Courses, Seminars & Conferences

Deposition and assembly of particles and polyelectrolytes: Influence of surfactants, type of polyelectrolyte, cations and pH

Prof. Claudine Filiâtre,

Institute UTINAM – UMR CNRS 6213 –University  Bourgogne Franche-Comté

16 Route de Gray, Bât C, 25030 Besançon cedex, France

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An expanded area in material processing is the controlled assembly of functionalised colloidal particles on a substrate. The production of these materials is of interest in a large range of applications such as composite coatings, adhesion of paints, optical and electronic devices, biological and chemical sensors.

Results of particle deposition on a cathode by electrophoretic deposition (EPD) or on an insulating substrate by electrostatic interactions are presented. The deposition and assembly of nanometer to micrometer size range particles and of polyelectrolytes are investigated in situ and in real time using two specific home-made apparatus. The particle deposition mechanism can be described as consisting of two successive steps: (a) transport of the particles from the solution toward the substrate and (b) adhesion of the particles onto the substrate. Different types of particles are used: organic, inorganic and raspberry-like particles functionalized with cationic surfactant (CTAB…) or with a layer by layer (LbL) polyelectrolyte assembly (chitosan, alginate, PEDOT:PSS…). For EPD experiments, we show that the local pH, the type of surfactant counter-ion or LbL has an influence on particle velocity near the electrode and on their assembly. By modulating different experimental parameters such as surfactant counter-ions, number of polyelectrolyte layers, pH and applied potential quasi-complete and irreversible coverage of the metallic surface can be obtained. Thin conductive films on an insulating substrate are also obtained by electrostatic assembly of polyelectrolytes and particles. The thickness and the conductivity of the films depend on the type and concentration of polyelectrolytes, the number of layers but also the nature of electrolytes (divalent cations).

Claudine Filiatre

Claudine Filiâtre, born in 1956, worked for ten years in a material research laboratory (Gaz de France), where she studied corrosion problems and the mechanical engineering of materials. She presented a Ph-D in 1994 at the University of Franche-Comté, Besançon, France, on the analysis and modelisation of a quartz-crystal microbalance for electrolytic coating applications. She joined the group Chemistry at interfaces heading by Pr Foissy in 1998 and is now Professor in the group “Matériaux et Surfaces Fonctionnalisés” of the Institute UTINAM – UMR CNRS 6213, at the University of Bourgogne Franche-Comté. She is involved in education (chemistry, colloids, rheology and crystallography) and in international and industrial research programmes.

Her research interests mainly concern the modification and the characterisation of colloids surface chemistry, the characterization of suspensions (rheology), the polyelectrolyte adsorption and the control of interactions between molecules, particles and substrates to realize multifunctional materials. She designed a specific apparatus to transport particles toward a conductive substrate in a laminar flow cell and to study in situ and in real time their electrophoretic deposition. Another specific apparatus, based on fixed-angle laser reflectometry, is also used to follow the build-up of the polyelectrolyte multilayer (layer by layer) or the electrophoretic deposition of nanometric particles in an impinging jet cell.