Laboratoire Matière et Systèmes Complexes

Numerous applications involve surface modification of colloidal particles or flat surfaces with polymers towards different material properties. Polyelectrolytes are an important class of polymers that are widely used for these purposes, especially after the development of layerby-layer (LbL) deposition technique. There are now a number commercial products based on materials obtained by LbL. LbL on colloidal particles is also achieved, however with the limitations of small scale production. An approach to scale-up LbL on nanoparticles based on a continuous ltrafiltration set-up will be demonstrated. Also, alternative to LbL, a new method based on simultaneous spraying of interacting species will be presented as an effective tool for preparation of a variety of thin films on surfaces as well as nanomaterials in solution Extremely user-friendly, these one-step processes allow preparing a variety of types of films and materials, such as inorganic coatings, polyelectrolyte-small oligoion complexes, 3-component complexes, and emulsions. For a better understanding of deposition of polyelectrolytes on particles, a fundemantal thorough study will also be presented. Adsorption of polyelectrolytes, both cationic and anionic, with a wide range of molecular masses adsorbing on different particles, was investigated by electrophoresis and light scattering. The dependence of the adsorbed amount of polyelectrolyte and of the hydrodynamic layer thickness on the molecular mass and the salt level is analyzed, where astonishing generic phenomenon is observed, regardless of the type of polyelectrolyte-particle pair used.