A molecular dynamics study of methyl group rotation in poly(vinyl methyl ether)

This paper presents a molecular modeling study of the methyl group rotations in poly(vinyl methyl ether) (PVME), which are sufficiently fast to be accessible by molecular dynamics. Simulation cells were produced and validated by a comparison of simulated X-ray scattering data with experimental measurements. The behavior of the methyl groups was analyzed in terms of transitions between three equivalent states both directly in terms of the transition rate and also by fitting a conformational state autocorrelation function. The results compare well with those of neutron scattering data available in the literature. A detailed study of individual group behavior shows that at high temperatures all methyl groups tend to behave in a similar fashion, with each methyl group exhibiting a nonexponential decay of the correlation function, while at lower temperatures individual groups behave differently, each group tending to a single-exponential decay of the correlation Function but with a wide range of decay times.