A combination of anionic and nitroxide-mediated radical polymerizations (dual initiator) was employed for the synthesis of poly(n-hexyl isocyanate-b-N-vinylpyrrolidone) (PHIC-b-PNV-P) block copolymers. The samples were characterized with a size exclusion chromatograph equipped with refractive-index and light scattering detectors as well as H-1 NMR spectroscopy. Relatively good control over the molecular weights was achieved. However, rather broad molecular weight distributions were obtained. The micellar properties of the PHIC-b-PNVP block copolymers were studied in water, which is a selective solvent for the poly(N-vinylpyrrolidone) blocks. Static and dynamic light scattering revealed the presence of equilibrium between the micelles and clusters. The clusters partially deaggregated with increasing temperature. (c) 2006 Wiley Periodicals, Inc.