Berlin 2012 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 33: Polymer Dynamics

CPP 33.7: Talk

Thursday, March 29, 2012, 11:45–12:00, C 264

Rigid vs flexible polyelectrolytes: Structural forces and rheology in nm scale volume — •Cagri Üzüm and Regine v. Klitzing — Stranski-Laboratorium, Institut für Chemie, TU Berlin, Strasse des 17.Juni 124, 10623 Berlin, Germany

In this contribution, flexible and rigid polyelectrolytes (i.e. NaPSS and DNA) in aqueous medium are compared with respect to two small scale dynamic parameters. First, the existence and dynamics of oscillatory structural forces in confinement were studied by colloidal probe AFM. In accord with theoretical calculations, structural forces are suppressed with increasing chain rigidity, presumably due to a longer chain reorientation time in the confinement [1].

Second parameter is the newly introduced micro-viscosity, which corresponds to the viscosity in nm scale volumes. It was measured by an AFM microcantilever [2]. While the solutions of flexible chains have nearly the same micro-viscosity as the bulk, rigid chains have significantly lower ones as compared to the bulk viscosity. Possible reasons for this significant difference are addressed.

[1] Kleinschmidt, F.; Stubenrauch, C.; Delacotte, J.; von Klitzing, R. and Langevin, D. J. Phys. Chem. B, (2009), 113, 3972-3980

[2] Boskovic, S.; Chon, J.; Mulvaney, P. and Sader, J. J. Rheol., (2002), 46, 891-899