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Updated: Aug 16, 2026

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
A field-dissociation relation for polyelectrolytes with an application to field-induced conformational changes of
Abstract:
An extension to polyelectrolyte solutions of Onsager's field-dissociation relation for weak electrolytes can be derived in a simple way. It is found that, except in the limit of zero ionic strength, a strong applied electric field prevents counterion condensation from proceeding to completion. The extent of incompleteness initially varies linearly with the applied field. The field-dissociation relation can easily be incorporated into the theory of ionic effects on the stability of ordered polynucleotide structures, whereupon a dependence of the stability on field strength emerges. An explicit calculation for a co-operative transition of the DNA melting type is presented, and it is concluded that for sufficiently low ionic strengths, a field of the order of 10 kV/cm may be able to induce melting by lowering the Tm by a few degrees. The threshold effect found experimentally by Pörschke, and particularly the observed linear dependence of the threshold field on the logarithm of the ionic strength, appears here as a simple consequence of the linear increase of the stabilization free energy with the logarithm of ionic strength.
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