Macromolecules, Vol.44, No.3, 660-670, 2011
Universal Behavior of Dendrimer Solutions
The effect of molecular topology on the structural and dynamic properties of dendrimers with different generation numbers and molecular weights is studied in solvents of varying solvent quality and compared with the behavior of linear polymer chains of similar molecular weights. Brownian dynamics simulations are used, with a coarse-grained bead-spring chain model for the dendrimer, and both intramolecular hydrodynamic and excluded volume interactions are incorporated. The successive fine graining technique is applied to obtain parameter free predictions of properties as a function of solvent quality. In particular, it is shown that with a suitable definition of the solvent quality parameter, the swelling of dendrimers with increasing solvent quality can be collapsed on to a single master curve for molecules with the same topology. The swelling of dendrimers is found to cause a decrease in the translational diffusivity, and a shift in the characteristic maximum in intrinsic viscosity with molecular mass to higher generation numbers. Ratios of the radius of gyration to the hydrodynamic and viscometric radii converge to constant universal values for dendrimers with a fixed degree of branching.