Surface-Iniatiated Anionic Polymerization: Tethered Polymer Brushes on Silicate Flat Surfaces

Recently, there has been much interest in using Surface Initiated Polymerization (SIP) in preparing organic-inorganic delaminated nanocomposites. These nanocomoposites have generated much interest because of their potential for applications in high barrier coatings, electronic materials, catalysis, and fundamental studies of polymers in confined environments. Polymer clay/silicate composites have been investigated for a number of years. One of the best ways to achieve control of their application properties is by direct covalent attachment of polymer chains to the particle surfaces using appropriate polymerization methods. Here we report the formation of polystyrene films grafted from silicate surfaces by the living anionic polymerization of styrene. Activated 1,1-diphenylethylene (DPE)-chlorosilane initiation sites were formed by self-assembled monolayers (SAM) on flat silicate surfaces. We have characterized these films by contact angle measurements, atomic force microscopy, attenuated total reflection FT-IR, X-ray photoelectron spectroscopy, and ellipsometry. Our results indicate the formation of ultrathin films with unique morphologies and brush densities, as compared to previously polymerized films made by free-radical mechanisms. Thus, they provide insight to differences in anionic versus radical polymerization in surfaces and facilitate new possibilities for block and graft copolymerization from surfaces in the future.