Structural relaxation in poly(ethylene oxide)-salt solutions

We present the results of molecular dynamics simulations of PEO(x)Nal polymer electrolytes, performed to study the influence of NaI on the dynamics of PEG. By calculating the mean square displacement of the CH2 groups we observe that the Rouse-like motion, typical for short polymer chains, is slowed down under the influence of NaI. This slowing down is also observed in the self part of the intermediate scattering function F-s(k, t), as an increase in the relaxation time. By using the Gaussian approximation it is shown that the stretched exponential relaxation in the small k-limit of F-s(k, t) is a result of the Rouse-like motion of the polymers. We find that our results are in good agreement with neutron spin-echo experiments. (C) 2000 Elsevier Science B.V. All rights reserved.