Title: The physics of active polymers and filaments.

Speaker: Prof. Roland Winkler

Abstract:

Active soft matter composed of filaments or polymers is a promising new class of materials due to the tight coupling between the nonequilibrium dynamics and the polymer conformations [1]. There are various realizations of active polymers. ATP-dependent enzymatic activity-induced mechanical fluctuations drive molecular motion in the cytoplasm of bacteria and eukaryotic cells and affect the properties of DNA/RNA molecules. Linear polymers, such as filamentous actin or microtubules of the cell cytoskeleton are propelled by tread-milling and motor proteins. In addition, the dynamics of passive colloidal particles and polymers is enhanced in a bath of propelled filaments [1].

We analyze the conformational and dynamical properties of self-propelled ring and linear polymers by analytical theory and computer simulations. Two models for active driving are considered, polymers with active sites represented by active Brownian particles (ABPs) (active Brownian polymers, ABPOs) [1] and polymers driven by tangential forces (active polar linear polymers, APLPs) [2]. In case of ABPOs, activity leads to a swelling of flexible and, at intermediate activities, shrinkage of semiflexible polymers followed by a reswelling at large activities. In contrast, the conformations of tangentially driven polymers are independent of activity. In general, activity yields a drastic acceleration of both, the center-of-mass and the intramolecular dynamics. Interestingly, accounting for hydrodynamic interactions in ABPOs leads to shrinkage of even flexible polymers at intermediate activities. A comparison between ABPOs and APLPs shows distinct differences in their diffusive behavior, in particular the relevance of the intramolecular dynamics and the dependence on the activity. The various aspects will be addressed in the presentation.

[1] R. G. Winkler, G. Gompper, J. Chem. Phys. 153, 040901 (2020)

[2] C. A. Philipps, G. Gompper, R. G. Winkler, Phys. Rev. E 105, L062501 (2022), C. A. Philipps, G. Gompper, R. G. Winkler, J. Chem. Phys. (2022)

This event will take place in room L0.12 (in the Lab42 building). Please note that both time and location are different from usual.