Regensburg 2013 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 23: Polymer Dynamics
CPP 23.8: Talk
Wednesday, March 13, 2013, 11:45–12:00, H39
Unwinding polymer globules under stretching force: A Monte Carlo study — •Christoph Jentzsch1,2, Marco Werner1,2, and Jens-Uwe Sommer1,2 — 1Leibniz-Institut für Polymerforschung Dresden, Germany — 2Technische Universität Dresden, Germany
We investigate linear polymer chains under poor- and non-solvent conditions using the bond fluctuation model with explicit solvent. By implementing many-body effects implicitly, this model allows for free diffusion of polymer globules under non-solvent conditions on the same time scale as in good solvent while keeping the computational effort low as compared to off-lattice calculations. We analyze static and dynamic properties of polymer globules in poor solvent. We further calculate the force acting on chain ends, when they are fixed at a given distance. Our results for the force-extension curve are qualitatively in good agreement with recent experiments and with numerical results using a self-consistent field approach. For distances slightly larger than the globule diameter, we observe a tadpole regime where one stretched part of the chain is in equilibrium with a single residual globule. The force necessary to form a stable tadpole conformation as function of solvent quality can be understood using scaling arguments based on the thermal blob size. For increasing distances, we observe a decay of the tadpole into smaller globules and stretched chain parts. Here, the stretching force shows a local minimum and a quantitative explanation for the observed shape of the force-extension curve remains a challenge. For larger distances a cross-over to a strongly stretched chain behavior is found.