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AKB: Biologische Physik

AKB 10: Biopolymers

AKB 10.4: Talk

Friday, March 4, 2005, 11:00–11:15, TU H2013

Towards a theory of the equilibrium phase behaviour of stiff polymer solutions — •Sven van Teeffelen, Erwin Frey, and Klaus Kroy — Hahn-Meitner-Institut Berlin

We study the equilibrium collective properties – packing structure and phase behaviour – of solutions of entangled stiff polymers that are isotropically dissolved in an aqueous salty solution in the presence of small flexible polymers mediating an additional depletion attraction. In order to make contact with well established liquid-state theories we calculate a microscopic effective pair potential between the filaments. We find that the bare interactions (hard core, depletion, electrostatic, van der Waals) are drastically renormalized by thermal fluctuations. In order to account for non-trivial cooperative effects at finite filament densities we make use of a scaling argument extending the tube model of semiflexible polymers. In particular, we find the spinodal in agreement with recent experiments on in vitro solutions of F-actin and Polyethylenglycol.