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AKB: Biologische Physik

AKB 50: Poster Session "Biological Physics"

AKB 50.5: Poster

Freitag, 12. März 2004, 10:30–13:00, B

Elasticity of Two-Dimensional Stiff Polymer Networks — •Claus Heussinger and Erwin Frey — Hahn-Meitner Institut, Berlin

We study the elasticity of two-dimensional networks of semiflexible polymers (No-dqMikado modelNo-dq). The essential features incorporated into the model are the random geometry of the network and the anisotropic elasticity of its constituents.

In a first study, the elements are modeled as purely mechanical Euler beams [1,2]. We show that there are three distinct scaling regimes, characterized by two characteristic length scales. In addition to a critical rigidity percolation region and a homogeneous elastic regime (dominated by beam compression) we find a novel intermediate scaling regime, where the elasticity of the network is dominated by bending deformations. The observations for the shear modulus can be rationalized by a crossover scaling ansatz that permits to collapse the data over eight orders of magnitude in the scaling variable.

In a second step, effective elastic properties of semiflexible polymers are implemented to study the entropic contributions to the polymer compliance and its effects on the scaling behaviour.

To get further insight into the nature of the force propagation, more complicated modes of deformation can be explored. As an example, we visualize force chains induced by the action of a microrheological probe.

[1] J. Wilhelm and E. Frey PRL 91, 108103 (2003)

[2] E. Frey, K. Kroy, J. Wilhelm and E. Sackmann, in Dynamical Networks in Physics and Biology (Springer Verlag Berlin, 1998)