Solubility and Purification of Mo6S4.5I4.5 Nanowires in Common Solvents

Keywords:
MoxSyIz, sedimentation, solubilization, purification

Abstract:
The discovery of inorganic one-dimensional nanostructures has attracted a great deal of attention because of various interesting properties correlating their characteristic chemical properties with their ease of fabrication and monodisperse, metallic nature. However the high expectations on these materials are strictly correlated with the possibility to disperse them easily and in common solvents and to develop sufficiently practical purification methods. In this work we have investigated the solubility of Mo6S4.5I4.5 nanowire soot in a range of common solvents by performing sedimentation studies and microscopic characterization. A sedimentation equation was derived showing that the concentration of any insoluble dispersed phase decreases exponentially with time. We find that in all solvents, Mo6S4.5I4.5 nanowire soot contains three phases, two of which are insoluble with one soluble phase. Scanning and Transmission electron microscopy have been used to identify and characterize each of the three phases. Fitting the sedimentation equation to the experimental sedimentation data gives the partial concentration of each phase. The sedimentation properties of the various phases did not result to vary significantly with concentration indicating that the insoluble nanowires are intrinsically insoluble. However, the diameter of the soluble bundles decreases with concentration, until very small bundles consisting of only two or three nanowires were observed at concentration below 0.003 mg/ml. In addition, stable composite dispersions were produced by mixing the nanowires with polyvinylpyrrolidone in isopropanol opening the way for the formation of polymer / inorganic nanowire composites.

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Nanotech 2005 Conference Program Abstract