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Fluctuations in the coil-stretch transition of flexible polymers in good solvents: a peak due to nonlinear force
Rangarajan Radhakrishnan1, Patrick T Underhill
1Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th St, Troy, New York 12180, USA.
Abstract:
Long flexible polymers undergo a coil to stretch transition (CST) in an elongational flow. Near the CST, a peak can be observed in the fluctuations of the size of a molecule (|R|). Solvent effects on the fluctuations are studied using Brownian dynamics simulations of a nonlinear spring force relation that can represent real molecules. Ignoring the influence of hydrodynamic interactions, a linear region in the spring force relation is known to cause the peak in |R| fluctuations. In contrast, we find that a peak in the fluctuations can be obtained even for the nonlinear spring force relation. We analyze the influence of hydrodynamic interactions on the fluctuations using a dumbbell model with a conformation-dependent drag coefficient.
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