SKM 2023 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Polymer and Molecular Dynamics, Friction and Rheology

CPP 20.9: Vortrag

Dienstag, 28. März 2023, 12:00–12:15, ZEU 255

On the Relaxation Behavior of Linear Chains under Oscillatory Forces — •Ron Dockhorn¹ and Jens-Uwe Sommer^1,2 — ¹Leibniz-Institut für Polymerforschung Dresden e.V., D-01069 Dresden, Germany — ²Technische Universität Dresden, Institut für Theoretische Physik, D-01069 Dresden, Germany

We are studying the relaxation spectra and the force-extension behavior of linear chains under externally driven oscillatory periodic forces f in means of theory and simulations. An oscillatory force f= f₀ + f_a · sin(ω t) is applied on the chain ends and the response of the end-to-end-distance R as well as the relaxation time τ_R on the oscillatory frequency ω is investigated. An analytical expression for the end-to-end-distance R(f) is derived by using the Rouse model and compared to simulations. The dissipated energy is calculated by the hysteresis loop A = | ∮df R(f) |, which shows a characteristic maximum at ω τ_R ≃ 1 for ideal chains independent of the applied force. Contrary, excluded volume chains show a force dependence on the relaxation time τ_R ∼ f^−0.3 as well as a shift on the hysteresis in the Pincus regime. Extensive computer simulations are performed to investigate the scaling properties utilizing the Bond-Fluctuation-Model. Furthermore, the relaxation behavior of different polymer architectures (ring polymer, 3₁-trefoil knot, two concatenate rings) are compared to the linear chain behavior. The theory and simulations suggests implications for dynamic experiments of biopolymer subject to external forces.