Stretch dynamics of flexible dendritic polymers in solution

Abstract

We study the stretch dynamics of flexible dendritic polymers (dendrimers and stars) under external forces. We work in the framework of the bead-spring model with hydrodynamic interactions (HI) and take spacers of different length into account. The applied fields may, e.g., be of mechanical or electrical origin. We study the motion of a specific monomer, the time evolution of the stretch (the mean distance of the monomer on which the force acts from the center of mass of the polymer) and also the elastic moduli. We analyze how these dynamic properties depend on the underlying topology, i.e., on the number of generations for dendrimers and the length and number of branches for stars. As a special point we assess in how far the HI method utilized here (the Kirkwood–Riseman scheme) is stable for dendritic structures. Characteristic for the topology is the intermediate dynamics (between short and long times). It turns out that, different from stars, for dendrimers the stretch dynamics is for intermediate times close to logarithmic; hence the crossover in behavior at intermediate times is characteristic of the polymer’s topology.