The synthesis of model linear and star double-comb polybutadienes, as well as molecular double-brush polybutadienes, with two tails emanating from each branch point, is presented. The synthetic approach involves (1) the selective reaction of living polybutadienes with the two chlorines of 4-(dichloromethylsilyl)styrene to make double-tailed macromonomers and (2) the homopolymerization or copolymerization of the double-tailed macromonomer, in situ without isolation, to produce the double brushes and double combs, respectively. The star double comb was synthesized by the reaction of living double-comb polybutadiene with trichloromethylsilane. Characterization carried out by size exclusion chromatography, with differential refractometer and light scattering detectors, indicated that the synthesized polybutadienes had a high degree of molecular and structural homogeneity. (c) 2005 Wiley Periodicals, Inc.