Layer-by-layer deposition of barrier and permselective c-oriented-MCM-22/ silica composite films

Abstract

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 [Ace. 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 chromáte 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. © 2007_ American Chemical Society.