Gas barrier properties of nanocomposites based on in situ polymerized poly(n-butyl methacrylate) in the presence of surface modified montmorillonite

Barrier membranes of poly(n-butylacrylate) were produced by the in situ polymerization of n-butylacrylate in the presence of surface modified natural montmorillonite. This two-stage process allowed control over the extent of intercalation, most likely leading to exfoliated nanostructures. The first stage of the process consisted of the organic modification of montmorillonite via ion exchange reactions with (acryloyloxy) ethyl alkylammonium cations. This process anchored chemically reactive species on the surface of natural clay and improved the mixing between the clay and the monomer. The second stage of the process comprised of the in situ polymerization of n-butyl methacrylate and the unsaturated acryloxy ethyl groups anchored on the surface of the clay. Resulting membranes were characterized in terms of their microstructure and diffraction (XRD), their thermal properties (TGA and DSC), and gas permeation properties. The resulting exfoliated morphology led to a decrease in gas permeability. Gas barrier properties of the nanocomposites were compared to those predicted by phenomenological models such as those of Cussler and Nielsen. (C) 2009 Elsevier B.V. All rights reserved.