Starburst polyelectrolytes: Scaling and self-consistent-field theory

Conformations of weakly charged starburst polyelectrolytes in dilute solution are studied as a function of the number of generations g, the length of spacers n, and the degree of ionization a. Scaling analysis is combined with extensive numerical self-consistent-field (SCF) calculations performed on the basis of an extended Scheutjens-Fleer (SF) algorithm. We demonstrate that the predictions of scaling analysis are applicable only for starburst polyelectrolytes with relatively small number of generations and sufficiently long spacers. We prove that irrespective of the strength/type of the intramolecular interactions the starburst macromolecules are characterized by a monotonic decay of the density profiles in the radial direction. In the case of a large number of generations a quasi-plateau in the monomer density profile is observed. This leveled-off distribution of density is due to strong fluctuations in the radial positions of branching points and end segments. In accordance with earlier Monte Carlo simulations results, we observe that the outer generations pull strongly on the spacers of inner generations.