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BP: Fachverband Biologische Physik

BP 26: Poster Session II

BP 26.14: Poster

Donnerstag, 29. März 2007, 17:00–19:30, Poster B

Counterion Dynamics at Charged Polymers: A Study of Electrophoresis — •Sebastian Fischer¹, Ali Naji^1,2, and Roland Netz¹ — ¹Physik Department, Technische Universität München, D-85748 Garching, Germany — ²Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA

Using the Brownian Dynamics simulation technique, we investigate the electrophoretic response of an infinitely long polyelectrolyte chain and its neutralizing counterions with respect to an external electric field. For large Manning parameters the well-known phenomenon of counterion condensation at long charged polymers tends to decrease the electrophoretic mobility of the polymer chain. In this case we find – as opposed to the common assumption made in theoretical modeling approaches [1] – that there generally is substantial slip between the condensed counterions and the polyelectrolyte. At fixed Manning parameter we observe considerable sensitivity of the electrophoretic mobility to the local chain architecture which we vary through either the charge spacing along the polymer backbone or the monomer-to-counterion size ratio. The influence of local features regarding the electrophoretic response of polyelectrolytes has only recently been pointed out in a capillary electrophoresis study of a synthetic polymer with variable charge spacing [2].

[1] G. S. Manning, J. Phys. Chem. 85, 1506 (1981)

[2] A. Popov, D. A. Hoagland, J. Polym. Sci. Part B: Polym. Phys. 42, 3616 (2004)