Ultrathin Molybdenum Polyoxometalate−Polyelectrolyte Multilayer Films

• Published in: Langmuir 1998-06, Vol.14 (13), p.3462-3465
• Main Authors: Caruso, Frank, Kurth, Dirk G, Volkmer, Dirk, Koop, Michael J, Müller, Achim
• Format: Article
• Language: English
• Subjects: Applied sciences; Composites; Exact sciences and technology; Forms of application and semi-finished materials; Polymer industry, paints, wood; Technology of polymers
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la980177v

Ultrathin multilayer films of a novel molybdenum(VI) polyoxometalate cluster ((NH4)21[H3Mo57V6(NO)6O183(H2O)18]) (Mo57) and poly(allylamine hydrochloride) (PAH) have been prepared by the consecutive stepwise adsorption of Mo57 and PAH from dilute aqueous solution. The Mo57/PAH multilayer films have been characterized by optical spectroscopy and small-angle X-ray reflectivity (XR) methods. UV−vis measurements reveal regular film growth with each Mo57 adsorption. The average Mo57 surface density was found to be (1.4 ± 0.4) × 1013 clusters per cm2, corresponding to an average surface coverage of 56 ± 12%. XR experiments confirm uniform film growth, with the film thickness increasing with each Mo57 adsorption step. The average thickness for the Mo57/PAH layer pair was determined to be 0.8 ± 0.1 nm. The Mo57 density in the film can be readily controlled by varying the polyelectrolyte interlayer separation between each Mo57 layer, and the total film thickness can be controlled by altering the number of adsorption cycles.