Bead spring models for polymers in solution are nonlinear if either the finite extensibility of the polymer, excluded-volume effects or hydrodynamic interactions between polymer segments are taken into account. For such models we use a powerful method for the determination of the complete relaxation spectrum of fluctuations at steady state. In general, the spectrum and modes differ significantly from those of the linear Rouse model. For a tethered polymer in uniform flow the differences are mainly caused by an inhomogeneous distribution of tension along the chain and are most pronounced due to the finite chain extensibility. Beyond the dynamics of steady-state fluctuations we also investigate the nonlinear response of the polymer to a large sudden change in the flow. This response exhibits several distinct regimes with characteristic decay laws and shows features which are beyond the scope of single-mode theories such as the dumb-bell model.
EPL (Europhysics Letters)
- Pub Date:
- September 2002
- Molecular dynamics Brownian dynamics;
- Condensed Matter - Soft Condensed Matter
- 7 pages, 3 figures