278589 Tube Diameter of Oriented and Stretched Chains Studied with Isoconfigurational Averaging

Tuesday, October 30, 2012: 5:05 PM
Butler West (Westin )
Jian Qin, Jungseob So and Scott Milner, Chemical Engineering, Pennsylvania State University, State College, PA

Tube is the key concept for understanding the flow properties of polymers. We investigate how the tube diameter varies with deformation in polymer melts using the isoconfigurational averaging method [1]. To conduct isoconfigurational averaging, we start with a well equilibrated (deformed) configuration, run molecular dynamics (MD) simulation multiple times, each with different initial velocities, and record bead positions at different times and along different MD trajectories. The bead positions form a cloud showing the shape, range and strength of the tube confinement, which enables us to study the tube diameter and other statistical properties of tube. We applied the isoconfigurational averaging to deformed ring and linear polymers simulated with the bead-spring model. Ring polymers are equilibrated by invoking various molecular rebridging moves in Monte Carlo simulations, and are subjected to a sequence of uniaxial compressions and stretches. The deformed configurations are allowed to re-equilibrate with the rebridging moves turned off, and then are analyzed using isoconfigurational averaging. We investigate the variation of the tube primitive path and the tube diameter with deformation, and compared the results to the predictions of affine deformation theory. For linear polymers, the force-extension law and the dependence of the tube diameter on stretching are obtained.

[1] Windsor Bisbee, Jian Qin, and Scott T. Milner, "Finding the Tube with Isoconfigurational Averaging", Macromolecules, 2011, 44(22):8972-898

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See more of this Session: Diffusion in Polymers
See more of this Group/Topical: Materials Engineering and Sciences Division