Conformational Properties and Intrinsic Viscosity of Dendrimers under Excluded-Volume Conditions

Abstract

The good-solvent expansion of dendrimers is theoretically studied by self-consistent free-energy minimization accounting for all the relevant degrees of freedom. This feature enables a description both of the local conformation and of the overall molecular behavior. Equilibrium and dynamical properties are calculated, in particular the radius of gyration and the viscometric radius (from intrinsic viscosity). The intramolecular swelling is concentrated in the core region, the individual dendra, sub-dendra, etc., being stretched outward with relatively little inter-dendron mixing. Appropriate reduced variables are found for the characteristic radii, which yield a unique master curve for any generation and solvent quality. We also propose an analytical fitting function that permits easy numerical calculation for all cases of interest. The intrinsic viscosity dependence on generation is discussed, including the possible existence of a maximum as experimentally observed in some cases.