Latex particles based on 1,4-polybutadiene were synthesized via dispersion ring-opening metathesis copolymerization of 1,5-cyclooctadiene with a alpha-norbornenyl poly(ethylene oxide) macromonomer. Stable but polydisperse colloidal dispersions in the 50 nm to 10 mum size range were obtained. In this work, particular attention was paid to the effects of the kinetics of copolymerization on the structure of the graft copolymers formed and on the onset of turbidity. Strategies to prepare monodisperse polybutadiene particles were also designed through the growth of a polybutadiene shell from a well-defined polynorbornene seed. (C) 2004 Wiley Periodicals, Inc.