Self-assembly of aluminium-pillared clay on a gold support

Multilayer films of self-assembled aluminium Keggin ion pillared laponite and saponite have been grown layer-by-layer on a gold support. 4-Aminothiophenol (4-ATP) was used for anchoring the first clay layer on the gold surface. Subsequently layers of clay and Al pillar were adsorbed by dipping the substrate into the appropriate solutions. Characterization of the films was performed by X-ray photoelectron spectroscopy (XPS), IR spectroscopy (FTIR–ERS), ellipsometric thickness measurements and X-ray diffraction (XRD). XPS elemental analysis showed that both clay and pillar were present on the gold substrate. From the atomic film compositions, the charges on the Keggin ions were determined to be +3 and +5 for laponite and saponite, respectively. Ellipsometry and IR spectroscopy indicated gradual and regular growth for both films. Structural order in the synthesized films was demonstrated by X-ray diffraction. The interlayer free spacing (IFS) was found to be 6 A by XRD, which corresponds to the increase in ellipsometric film thickness after each aluminium layer adsorption. Aluminium-pillared laponite films have been used as chemically sensitive films on surface acoustic wave (SAW) devices to measure the adsorption capacity of six volatile organic compounds (VOCs). The influences of the different terminal film layers and calcination-induced chemical changes on the extent of adsorption of the VOCs were investigated.

[1]  Antonio J. Ricco,et al.  Molecular Interactions between Organized, Surface-Confined Monolayers and Vapor-Phase Probe Molecules. 8. Reactions between Acid-Terminated Self-Assembled Monolayers and Vapor-Phase Bases , 1996 .

[2]  P. Grobet,et al.  The Al Pillaring of Clays. Part II. Pillaring with [Al13O4(OH)24(H2O)12]7+ , 1994 .

[3]  Thomas E. Mallouk,et al.  Layer-by-Layer Assembly of Intercalation Compounds and Heterostructures on Surfaces: Toward Molecular "Beaker" Epitaxy , 1994 .

[4]  R. Schoonheydt,et al.  The Al Pillaring of Clays. Part I. Pillaring with Dilute and Concentrated Al Solutions , 1993 .

[5]  J. R. Jones,et al.  Synthesis and characterisation of alumina pillared Texas montmorillonite and determination of the effective Keggin ion charge , 1993 .

[6]  Thomas E. Mallouk,et al.  LAYERED METAL PHOSPHATES AND PHOSPHONATES : FROM CRYSTALS TO MONOLAYERS , 1992 .

[7]  H. Leeman,et al.  Pillaring of saponite in concentrated medium , 1992, Clay Minerals.

[8]  R. Barklie,et al.  EPR of VO2+ ions in Al-pillared montmorillonite , 1990, Clay Minerals.

[9]  B. D. Roberts,et al.  Pillaring of layered zirconium and titanium phosphates , 1988 .

[10]  J. Sterte.  Synthesis and Properties of Titanium Oxide Cross-Linked Montmorillonite , 1986 .

[11]  M. Tokarz,et al.  Cross-linked Smectites. IV. Preparation and Properties of Hydroxyaluminum-Pillared Ce- and La-Montmorillonites and Fluorinated NH4+-Montmorillonites , 1985 .

[12]  R. Nuzzo,et al.  ADSORPTION OF BIFUNCTIONAL ORGANIC DISULFIDES ON GOLD SURFACES , 1983 .

[13]  T. Pinnavaia,et al.  Intercalated Clay Catalysts , 1983, Science.