The incremental addition of divinylbenzene was used to generate star polystyrenes in a nearly full conversion of a living polystyrenyl anion. The dramatic increase in the molecular weight of the star polystyrenes with a limited supply of the living polystyrene supported the formation of gradient-star polystyrenes through star-star coupling. The stoichiometric analysis of the star polymers revealed that their connection polymer had a shorter length than their branch polymer. The measured solution viscosity of the gradient-star polymers greatly deviated from a linear correlation with the molecular weight and was in parallel to a theoretical simulation based on a highly branched structure of the gradient-star polymer. (c) 2006 Wiley Periodicals, Inc.