Continuous self-assembly of organic-inorganic nanocomposite coatings that mimic nacre

Nanocomposite materials are widespread in biological systems. Perhaps the most studied is the nacre of abalone shell, an orientated coating composed of alternating layers of aragonite (CaCO3) and a biopolymer. Its laminated structure simultaneously provides strength, hardness and toughness: containing about 1 vol. % polymer, nacre is twice as hard and 1,000 times as tough as its constituent phases(1). Such remarkable properties have inspired chemists and materials scientists to develop synthetic, 'biomimetic' nanocomposite assemblies(2-5), Nonetheless, the efficient processing of layered organic-inorganic composites remains an elusive goal, Here we report a rapid, efficient self-assembly process for preparing nanolaminated coatings that mimic the structure of nacre. Beginning with a solution of silica, surfactant and organic monomers, we rely on evaporation during dip-coating to induce the formation of micelles and partitioning of the organic constituents into the micellar interiors(6). Subsequent self-assembly of the silica-surfactant-monomer micellar species into lyotropic mesophases(7) simultaneously organizes the organic and inorganic precursors into the desired nanolaminated form. Polymerization fixes this structure, completing the nanocomposite assembly process. This approach may be generalized both to other composite architectures and to other materials combinations.