Fabrication of Bragg stack films of clay nanosheets and polycations co-polymerization of intercalated monomers and functional interlayer cations

The fabrication of one-dimensional (1D) crystalline, monodomain nanocomposite films (hybrid Bragg stacks) is still limited to a few combinations of polymers and clay. The main reason is the segregation of clay and polymers driven by the entropic loss faced by the polymer confined in a narrow slit between the nanosheets. By exchanging synthetic sodium-fluorohectorite with vinylbenzyltrimethylammonium chloride, we succeeded in delaminating clay via 1D dissolution in N -methylformamide to obtain a liquid crystalline suspension. By combining this with bisphenol A glycerolate diacrylate, 1D crystalline nanocomposites could be obtained via photopolymerization of doctor bladed wet coatings. Infrared spectroscopy confirmed the co-polymerization of monomers and the organic modifier between the hectorite platelets. This single-phase hybrid material shows very low oxygen and water vapor transmission rates. The incorporation of the modified clay into the polymer leads to an oxygen transmission rate of 0.21 cm 3 m −2 day −1 atm −1 at 50% r.h. and 23 °C and a water vapor transmission rate of 0.05 g m −2 day −1 for a coating of 3.7 μm, making this material appropriate for challenging packaging applications. Functionalization by ion exchange allows synthetic hectorite to delaminate via 1D dissolution in N -methylformamide. Mixing with a diacrylate monomer and photopolymerization yields a 1D crystalline nanocomposite coating with improved gas barrier properties.