(248a) Slip-Link Simulations of Entangled DNA with Comparison to Experiments

The nonequilibrium dynamics of entangled polymers is a particularly complex process because of the interplay between the many known chain mechanisms including reptation, tube-length fluctuations, constraint renewal, and chain stretch. Recently, slip-link simulations, pioneered by Hua and Schieber (J. Chem. Phys. 1998), have been developed with the purpose of describing all mechanisms active in entangled polymer dynamics without ad hoc approximations. These simulations, though still a developing area of research, have turned out to be a powerful tool since their higher level of coarse-graining, relative to molecular dynamics, allows for simulations at much longer time scales. We have implemented such a sliplink-based model, originally proposed by Masubuchi et al. (J. Chem. Phys. 2001). The original version of model is further refined to account for more accurate description of chain end dynamics, finite extensibility effects and variable subchain friction for nonequilibrium dynamics (Masubuchi et. al., J. Chem. Phys. 2008). The model, along with the ?individual? mechanisms of reptation and tube length fluctuation, also incorporates the collective contributions arising from the 3D network structure of the entangled chains, including constraint release. With the new code, we have simulated both the static and dynamic responses of monodisperse linear worm-like chains and compared the simulations results with the experimental data reported by Jary et al. 1999 and Teixeira et al. 2007 for entangled DNA in shear flow. The simulations were run for monodisperse linear chains including up to 30 entanglements. Additionally, we also have the ability to perform implicit simulations. In the present work, we demonstrate (i) the effect of different constraint renewal (CR) procedures on the dynamics of the entangled chain network, such as the decrease in the number of entanglements and the effect of increased chain stretch on decreasing CR frequency (ii) in shear flow, the dynamic mechanisms that create the plateau in the steady shear stress and (iii) using modified Kraynik-Reinelt boundary conditions, we examine the dynamic chain mechanisms in extensional and mixed planar flows. The simulation model is able to capture the rheological behavior of entangled systems both in the linear and nonlinear range, though we demonstrate sensitivity to the procedure for creating re-entanglement.