Tethered polyelectrolytes under the action of an electrical field : A molecular-dynamics study

• Published in: The European physical journal. E, Soft matter and biological physics Soft matter and biological physics, 2007-05, Vol.23 (1), p.83-89, Article 83
• Main Authors: BERTRAND, M, SLATER, G. W
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemistry, Physical - methods; DNA - chemistry; Electrochemistry - methods; Electrolytes - chemistry; Electrophoresis; Exact sciences and technology; Models, Chemical; Models, Statistical; Molecular Conformation; Organic polymers; Physicochemistry of polymers; Properties and characterization; Solution and gel properties; Surface Properties
• ISSN: 1292-8941; 1292-895X
• DOI: 10.1140/epje/i2007-10179-2

For a polyelectrolyte undergoing electrophoretic motion, it is predicted (D. Long, J.L. Viovy, A. Ajdari, Phys. Rev. Lett. 76, 3858 (1996); D. Long, A. Ajdari, Electrophoresis 17, 1161 (1996)) that the mechanical force necessary to stall the molecule is substantially smaller than the sum of electrical forces applied on all monomers. In fact, it should be proportional to its hydrodynamic friction coefficient and therefore to the size of its conformation. In our work we examine this prediction using coarse-grained molecular-dynamics simulations in which we explicitly include the polymer, the solvent, the counterions and salt. The electrophoretic mobility of polyelectrolytes is evaluated, the mechanical force necessary to keep the molecules tethered is measured and the resulting anisotropic polymer conformations are observed and quantified. Our results corroborate Long et al.'s prediction.