Source:The Journal of Chemical Physics, 86:7174–7180, 1987
The dynamics of a probe chain consisting of nP =100 segments in a matrix of chains of length of nM=50 up to nM=800 at a total volume fraction of polymer ϕ=0.5 have been simulated by means of cubic lattice Monte Carlo dynamics. The diffusion coefficient of the probe chain over the range of nM under consideration decreases by about 30%, a behavior rather similar to that seen in real melts of very long chains. Furthermore, the analysis of the probe chain motion shows that the mechanism of motion is not reptation‐like and that the cage effect of the matrix is negligible. That is, the local fluctuations of the topological constraints imposed by the long matrix chains (even for nM=800) are sufficiently large to provide for essentially isotropic, but somewhat slowed down, motion of the probe, nP =100, chains relative to the homopolymer melt. The results of these MC experiments are discussed in the context of theoretical predictions and experimental findings for related systems.