Synthesis of Monodisperse GeO2 Particles in Reversed Micellar Systems
In order to examine the relationship between formation of particles and reaction field, the solubilized states of water in sodium 1,2-bis(2-ethylhexyloxycarbonyl)ethanesulfonate (AOT) in cyclohexane were studied by using some spectroscopic techniques at 30 °C. From the changes of these spectra features with Rw(=[H2O]/[AOT]), it is found that three typed water exist with varying proportions in the interior of micelles, i.e., at below Rw=4 water is bound directly to the polar groups of AOT, and in the range of Rw=4 to 11 the succeeded water is held together with the hydrated polar groups by the hydrogen bonds and at above Rw=11 bulk-like water is built up. These regions corresponding to each types of water were named as reversed micelles, swollen micelles and W/O microemulsions, respectively. On the basis of the phase diagram of water obtained, the synthesis of GeO2particles by the hydrolysis of Ge(OC2H5)4 were carried out at varing Rw in each region. Monodisperse polyhedron particles were produced in both the reversed and swollen micelle regions, whereas in W/O microemulsion ones cubic particles were formed. The size of these particles increased at Rw which change from reversed micelles to swollen ones, whereas that produced in W/O microemulsions rather decreased with Rw. All the particles obtained here were identified as α-quartz typed crystal, but that obtained at Rw=3 transformed to rutile-typed one at 1000 °C. These facts were recognized by X-ray diffraction analysis or FT-IR measurements.
KeywordsElectron Spin Resonance Reversed Micelle Bulk Water Solubilized State Microemulsion System
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- 4.Haering, G., Luisi, P.L and Hauser, H. (1988) Characterization by electron spin resonance of reversed micelles consisting of the terrnary system AOT-isooctane-water, 92, 3574–3581.Google Scholar
- 6.MagidL J. and Martin, C.A. (1984)13C NMR studies of molecular conformations and interactions in the curved surfactant monolayers of Aerosol OT water-in-oil micro-emulsions, in P.L.Luisi and B.E.Strub (eds), Reversed Micelles, Plenum Press, New York and London, pp. 181–193.Google Scholar
- 7.Kawai, T., Shindo, N. and Kon-No, K (1992) Solubilization behavior of water in hexaethylene glycol dodecyl ether reverse micelles in apolar solvents, J.Surface Sci. Technol., 8, 145–153.Google Scholar
- 9.Kon-No, K., Nakayama, T, and Kawai, T., Unpublished.Google Scholar