Polymer Dynamics

Semiflexible polymers in dilute solution

Experimental observations of the mean squared displacement of end-monomer dynamics of double-stranded DNA have produced conflicting results: for Rouse-like r2(t) ∼ t1/2 and Zimm-like r2(t) ∼ t2/3 scaling. We develop a theory of semiflexible polymer dynamics in order to resolve this controversy.

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1. "End-Monomer Dynamics in Semiflexible Polymers" by M. Hinczewski, X. Schlagberger, M. Rubinstein, O. Krichevsky, and R. R. Netz, Macromolecules 42, 860-875 (2009).

Translocation of a polymer through a small pore

The translocation of polymers chains through a narrow pore is one of the key phenomena in many biological systems. Combing scaling analysis, molecular dynamics simulation, as well as carefully designed experiments, we study the translocation mechanism, such as dependence of chain conformation and translocation time on polymer-pore interaction.

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Tube models (anomalous tube length fluctuations)

We study the dynamics of entangled polymer systems within the framework of the tube model. We find that contribution of tube length fluctuations to the stress relaxation is much larger than that included in the current theories. We are investigating the effect of tube length fluctuations on the behavior of loss and storage moduli in the intermediate frequency range.

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Dependence of tube diameter on polymer concentration

The tube diameter is one of the most important parameters used to describe polymer entanglements. We investigate the dependence of tube diameter on polymer concentration in an effort to understand their plateau modulus in various solvents.

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Dynamics of entangled rings

Entangled ring polymers without beginnings or ends in melt are subject to strong interactions with neighboring chains due to the presence of topological constraints. We study the size and conformation of ring polymers, as well as their diffusion, and stress relaxation in polymer melts.

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1. "Unexpected power-law stress relaxation of entangled ring polymers" by M. Kapnistos, M. Lang, D. Vlassopoulos, W. Pyckhout-Hintzen, D. Richter, D. Cho, T. Chang, and M. Rubinstein, Nature Materials 7, 997 - 1002 (2008).

2. "Dynamics of a Ring Polymer in a Gel" by S. P. Obukhov, M. Rubinstein and T. A. Duke, Phys. Rev. Lett. 73, 1263-1266 (1994).

3. "Dynamics of Ring Polymers in the Presence of Fixed Obstacles" by M. Rubinstein, Phys. Rev. Lett. 57, 3023-3026 (1986).