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Lecture Lee Peter Yezek


28 September 2004 FWN-Building 5116.0116, Nijenborgh 4, 9747 AG, Groningen
Speaker: Dr. Lee Peter Yezek
Affiliation: Dept. of Physical Chemistry and Colloid Science, Wageningen University
Title: Electrokinetics of thin films of charged co-polymer gels
Date: Tue Sep 28, 2004
Start: 13.00
Location: FWN-Building 5116.0116
Host: P. Rudolf
Telephone: +31 50 363 4736


Streaming potential and conductivity measurements were carried out on thin films of porous polymer gels of varying fixed charge density. The films consisted of gels of polyacrylamide-co-acrylic acid cross-linked with N,N'-methylenebis-acrylamide. The gel synthesis is based on the procedure developed by Zhang and Davison for the synthesis of neutral gels for use in Diffusion Gradient in Thin Films (DGT) devices for metal ion speciation. The gel samples were prepared in the form of thin films 0.25 mm thick. The equilibrium gel thickness varied as a function of fixed charge density due to osmotically driven swelling. Streaming potential and conductivity measurements were carried out as a function of ionic strength for a variety of gel preparations of varying polymer composition. Conductivity data allowed the estimation of the equilibrium Donnan potential difference which develops between the bulk gel phase and the electrolyte solution as a function of ionic strength. The relationship between the experimentally determined Donnan potentials and the measured streaming potentials is examined in the context of a new theory of the electrokinetics of soft surfaces put forth by Duval and van Leeuwen, as well as with the model of Ohshima and Kondo. The limitations of each model are discussed in the context of the experimental data for cross-linked polyacrylamide gels.
Last modified:22 October 2012 2.30 p.m.