Structural study of 3D-hexagonal mesoporous spin-coated sol–gel films

Mesostructured films deposited on glass substrates by spin coating are studied by X-ray diffraction, small angle X-ray scattering using grazing incidence (GISAXS) and high resolution electron microscopy. The films generally present a gradient of ordering from the air/sol interface to the interior of the film, with a 3D-hexagonal mesophase near the surface and a disordered micellar structure at the interior. However, the 3D-hexagonal ordering and the texturing can be extended over all the film thickness by adjusting the composition of the deposited solution. In particular, critical values are clearly observed both for the size of silica units forming the walls in the mesophase and for the film thickness. All these results can be understood from the competition between structuration and gelation of the films during alcohol removal.

[1]  S. Holt,et al.  Observation of hexagonal crystalline diffraction from growing silicate films , 1999 .

[2]  J. B. Higgins,et al.  A new family of mesoporous molecular sieves prepared with liquid crystal templates , 1992 .

[3]  Bruce Dunn,et al.  Continuous formation of supported cubic and hexagonal mesoporous films by sol–gel dip-coating , 1997, Nature.

[4]  J. Boilot,et al.  Sol-gel condensation of rapidly hydrolyzed silicon alkoxides: A joint 29Si NMR and small-angle x-ray scattering study. , 1990, Physical review. A, Atomic, molecular, and optical physics.

[5]  M. Ogawa.  Formation of Novel Oriented Transparent Films of Layered Silica-Surfactant Nanocomposites , 1994 .

[6]  Chang Hyun Ko,et al.  Disordered molecular sieve with branched mesoporous channel network , 1996 .

[7]  Ji Man Kim,et al.  Mesocrystal engineering using non-bonded interaction to obtain optically transparent mesoporous silica films and plates with uniform orientation , 1998 .

[8]  Fredrickson,et al.  Triblock copolymer syntheses of mesoporous silica with periodic 50 to 300 angstrom pores , 1998, Science.

[9]  S. M. Gruner,et al.  Biomimetic Pathways for Assembling Inorganic Thin Films , 1996, Science.

[10]  Sung June Cho,et al.  Optically Transparent, Single-Crystal-Like Oriented Mesoporous Silica Films and Plates , 1997 .

[11]  Geoffrey A. Ozin,et al.  Free-standing and oriented mesoporous silica films grown at the air–water interface , 1996, Nature.

[12]  M. Ogawa,et al.  PREPARATION OF SELF-STANDING TRANSPARENT FILMS OF SILICA-SURFACTANT MESOSTRUCTURED MATERIALS AND THE CONVERSION TO POROUS SILICA FILMS , 1998 .

[13]  Bradley F. Chmelka,et al.  Continuous Mesoporous Silica Films with Highly Ordered Large Pore Structures , 1998 .