Nonequilibrium relaxation of a stretched polymer chain

The static and nonequilibrium dynamic properties of a single linear polymer chain under a traction force $f$ is studied by Monte Carlo simulations using a continuous model and by scaling calculations. Chain lengths from $N=10\mathrm{}$ to 100 are considered. For the static results, our simulation data show that the averaged end-to-end distance $〈R_f〉\sim N^{2\nu }f$ at weak tension forces and for strong forces $〈R_f〉\sim {\mathrm{Nf}}^{1/\nu -1}$, which are consistent with previous studies. The nonequilibrium relaxation behavior is studied for an initially stretched polymer chain, when the stretching force is removed. Detail chain configurations during the relaxation process are analyzed from the simulation data. Different relaxation dynamics are found for three regions: the linear, Pincus, and model-dependent regimes. The nonequilibrium relaxation time $\tau$ is derived in the linear $\left(\tau \sim N^{1+2\nu }\right)$, Pincus $\left(\tau \sim N^2{f}^{1/\nu -2}\right)$, and model-dependent regimes. These results are compared with our Monte Carlo data and recent experiments, and are discussed in the light of scaling theories.