Hydrodynamic effects on the extension of stars and dendrimers in external fields

We assess the influence of hydrodynamic interactions on the extension of branched polymers subjected to external forces. We envisage that the macromolecules move under external applied fields, exemplified by mechanical or electrical micromanipulations. We focus our attention on the difference of the results obtained using the Rouse and the Zimm models, both of which represent an extreme situation, so that the realistic behavior is encompassed by the two models. We focus on the mean displacement of a specified monomer, on the shape which the macromolecule attains and on the structural average of the displacements involved. We discuss how these dynamic properties depend on the underlying topology, such as the number of branches and their length for the stars and on the number of generations for the dendrimers. Interestingly, although there exist quantitative differences between the results of the Rouse and of the Zimm model, in both models there appear typical dynamical features which depend on the topology only. This stresses the role of the structure on the dynamics and offers the possibility of tracking it under realistic, experimental conditions