Chain Stiffness Intensifies the Reptation Characteristics of Polymer Dynamics in the Melt

The reptation concept in polymer dynamics is studied for model chains with added stiffness. The main idea of a chain diffusing inside a tube can be transferred from fully flexible chains, within some limitations. The entanglement length shrinks with increasing persistence length. If entanglement length and persistence length come to the same order of magnitude the picture of a “tight tube” is better suited since any transverse motion is much reduced. Thus, as stiffness increases, the monomers lose their freedom to perform random walks inside the tube, the “Rouse-like” part of their dynamics. The picture shows snapshots of a polymer chain; the reptation of the ends (1–4) can be noted.