Unique Behavior of Dendritic Macromolecules: Intrinsic Viscosity of Polyether Dendrimers

Abstract

Poly(3,5-dihydroxybenzyl alc.) dendrimers made by the convergent growth approach are characterized by size exclusion chromatog. (SEC) with coupled mol.-wt.-sensitive detection. SEC chromatograms are as narrow as chromatograms of polystyrene with mol.-wt. distributions .apprxeq. 1.04, and do not broaden appreciably with increasing dendrimer generation, g. Values of wt.-av. mol. wt. obtained from light scattering detection are in agreement with the mol. wts. of the structures anticipated from the synthetic strategy. Intrinsic viscosity, obtained from SEC viscosity detection, passes through a characteristic max. as a function of g, while the refractive index increment appears to pass through a min. Hydrodynamic radii, calcd. from intrinsic viscosity data, increase approx. linearly with dendrimer generation. The data are in agreement with recent simulations of Lescanec and Muthukumar that predict a max. in intrinsic viscosity as a function of g. This suggests, but does not directly prove, that the d. of these dendrimers decreases monotonically from the center.

DOI
10.1021/ma00035a017
Year