(85f) Galvanostatic Measurements of Double Layer Formation in Doped Nonpolar Liquids

Galvanostatic Measurements of Double
Layer Formation in Doped Nonpolar Liquids

Ben Yezer, Paul J Sides, and Dennis C
Prieve          

Department of Chemical Engineering

Carnegie Mellon University

Pittsburgh, PA 15213

Amphiphilic
surfactants are often added to nonpolar liquids to electrostatically stabilize
particle suspensions in nonpolar media.  The surfactant molecules form reverse
micelles a few of which can acquire charges by exchanging a proton during
Brownian collisions.  These charged micelles then serve as charge carriers in
nonpolar media and facilitate surface charges on solid particles.  Previous
work^1,2,3 has studied the formation of the diffuse counterion cloud
when current is passed through doped nonpolar fluids held between parallel plate
electrodes.  In past experiments, the transient current response to a constant
applied voltage is measured.  This work introduces a galvanostatic method in
which a potential is measured in response to a constant current through 10 μm thick solutions of OLOA 11000 in dodecane.  One
advantage of constant current is the easy determination of the dielectric
constant of the fluid.  Other fluid properties including the conductivity and total
number of charge carriers are calculated from the transient potential response
to a constant current.  A corresponding model describes the migration of charge
carriers in the cell as diffuse clouds of charged micelles accumulate at either
electrode, leading to a better understanding of the dynamics of charge carriers
in nonpolar fluids.

¹D. C. Prieve, J.
D. Hoggard, R. Fu, P. J. Sides, and R. Bethesa, Langmuir 24, 1120
(2008)

²P. Kornilovitch,
Y. Jeon, J. Appl. Phys. 109, 064509 (2011)

³F. Strubbe, A.
R. M. Verschueren, L. J. M. Schlangen, F. Beunis, K. Neyts, J. Colloid
Interface Sci. 300, 396 (2006)