Layer-by-Layer Deposition of Barrier and Permselective c-Oriented-MCM-22/Silica Composite Films

A layer-by-layer deposition method is presented for the fabrication of compact c -oriented-MCM-22/silica films on aluminum alloys and porous α-alumina discs. The film fabrication procedure combines deposition of platelike MCM-22 crystals on substrates by covalent attachment under reflux and/or by sonication-assisted covalent attachment (using the methods introduced by Yoon and co-workers and recently reviewed [ Acc. Chem. Res . 2007, 40 (1), 29−40]) with evaporation-induced-self-assembly (EISA) of surfactant-templated silica. The composite c -oriented MCM-22/silica films exhibited corrosion resistance barrier properties comparable to commercial chromate conversion coatings. Moreover, they exhibited hydrogen ideal selectivities (e.g., H 2 /N 2 ∼ 7) above those expected by Knudsen diffusion indicating molecular sieving potential.