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A contribution to the understanding of percolation phenomena in binary liquids

Hernandez Perni, Maria Engracia. A contribution to the understanding of percolation phenomena in binary liquids. 2004, Doctoral Thesis, University of Basel, Faculty of Science.

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Official URL: http://edoc.unibas.ch/diss/DissB_6850

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Abstract

In the present work it was shown the important role of the Ei/E parameter in the
characterization of polar liquids. It could be demonstrated that the application of the broad
range dielectric spectroscopy together with the analysis of the quasi-static permittivity
using the modified Clausius-Mosotti-Debye equation can be used to detect percolation
phenomena in binary polar liquid mixtures. It leads to a valuable insight into the structure
of polar liquids and to a better understanding of binary systems. However, it has to be kept
in mind, that besides of percolation thresholds as critical concentrations it is also possible to
detect a change of the coordination number as a function of the volume ratio of the
components, which involves a change of the lattice type. It is sometimes difficult to
discriminate between pc or lattice change and more studies are needed in order to
distinguish between these two processes. It might also be useful to add additional analytical
methods. It was possible to clarify the non-linear behavior of the DMSO-water mixtures founded in
different measured physical properties. This was possible by measuring dielectric
spectroscopy parameters such as the Ei/E parameter obtained through the modified
Clausius-Mossotti-Debye equation, g-values obtained from the Kirkwood-Fröhlich
equation, relaxation time and dielectric constant and comparing them with literature data
concerning the viscosity, adiabatic compressibility and freezing point of binary solvent
mixtures. The results were interpreted in the frame of percolation theory. The values of the
lower and upper percolation thresholds are comparable and it is of interest, that as a
function of the parameter studied, only one or two percolation thresholds can be detected. It
is necessary to remark that despite the large number of techniques that have been applied to
the study of the DMSO-water system, the behavior of this system is still a mystery. For future pharmaceutical research it could be interested to extend the dielectric
spectroscopy studies to the Nanotechnology. This is in my view an exciting perspective.
Stromme (Proc. SPIE Int. Soc. Opt. Eng. 5118 pp 310-322, 2003) demonstrated how
dielectric spectroscopy can be used as a tool to obtain insight about properties on the nanoscale
of interfaces of pharmaceutical interest. An outline for studying the adhesion in terms
of a compatibility factor between pharmaceutical gels and biological tissue was put
forward.
Advisors:Leuenberger, Hans
Committee Members:Hoogevest, Peter van
Faculties and Departments:05 Faculty of Science > Departement Pharmazeutische Wissenschaften > Pharmazie > Pharmazeutische Technologie (Huwyler)
Item Type:Thesis
Thesis Subtype:Doctoral Thesis
Thesis no:6850
Thesis status:Complete
Bibsysno:Link to catalogue
Number of Pages:177
Language:English
Identification Number:
Last Modified:23 Feb 2018 11:40
Deposited On:13 Feb 2009 14:54

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