Nonequilibrium Brownian dynamics (NEBD) simulations are used to model the dynamics of six generations of dendrimers undergoing shear flow. A coarse‐grained bead‐spring model is proposed, which incorporates springs with stretching and bending potentials. The bending constant is used as one of the primary independent variables to control the deformability of the molecules. Rheological and conformational properties, such as viscosity, normal stress differences, visco‐elastic moduli, flow birefringence, mean square radius of gyration, and degree of prolateness, are observed under both transient (startup and cessation of flow) and steady‐state conditions. Comparisons are made with the corresponding linear chain analogs of the same molecular weight. The model qualitatively describes many of the experimentally observed effects in these systems, most notably a Newtonian viscosity profile (no shear thinning) and a maximum in the dependence of the intrinsic viscosity on the molecular weight. The dendrimers are also characterized by negligible start‐up overshoots in the transient viscosity and birefringence.

Brownian dynamics simulations have been performed on a variety of mixed linear-branched molecules. The rheological properties of three different constant molecular weight systems, with varying ratios of linear segments to branch points, are reported. The transition from perfectly branched behavior (low viscosity) to linear-chain-like behavior (high viscosity) is found to occur at a mole fraction of linear segments of 0.8.

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The approach of Blackwell et al. is used to model the rheology of concentrated hyperbranched polymeric systems. Model predictions for a poly(ether imide) hyperbranched system are in good quantitative agreement with the experimentally observed behavior of AB/AB2 copolymers. The poly(ether imide)s are especially suitable for studies of entangled dynamics because of their low entanglement molecular weight. A 3−4 orders of magnitude rise in the zero shear viscosity is observed as the mole fraction of linear segments is varied from 0 to 1. The average mass of segments between branch points is the most significant architectural parameter that affects the rheology of these systems.

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