ASSEMBLY OF POLYELECTROLYTE MOLECULAR FILMS ONTO PLASMA-TREATED GLASS

We combine in a unique approach two modern ultrathin film techniques for production of heterostructure films. These are plasma deposition (which permitted one to obtain thin 20-500-angstrom well-defined layers on any solid surface with an active, in our case charged, surface) and layer-by-layer deposition of the polycation/polyanion self-assembly. The latter technique was recently developed in our group and is based on the electrostatic attraction between opposite charges. Alternating adsorption of anionic and cationic polyelectrolytes from their aqueous solution onto charged substrate leads to the formation of multilayer assemblies. The multilayer heterostructure film was monitored by small-angle X-ray reflectivity. Oxygen, methane, argon, and polysiloxane plasma coating were tested as a precursor treatment for polyion assembly. The procedure was successfully accomplished for methane plasma deposition onto a glass substrate with further oxidation and consequent alternate assembling of a layer of polyallylamine (PAH) and polystyrenesulfonate (PSS). The step size of growth for the deposited PAH/PSS pair was 50 +/- 1 angstrom. Model fitting of the X-ray reflectivity data allowed us to calculate the electron density profiles of plasma-deposited plus polymer-assembled heterofilms and to characterize the thickness and roughness of its composite layers. Furthermore, the combination of methane plasma treatment and polyelectrolyte self-assembly opens a new approach for constructing inorganic/organic nanocomposite films.