Amphiphilic dendritic-linear-dendritic triblock copolymers based on hydrophilic linear poly(ethylene oxide) (PEO) and hydrophobic dendritic carbosilane were synthesized with a divergent approach at the allyl end groups of diallyl-terminated PEG. Their micellar characteristics in an aqueous phase were investigated with dynamic light scattering, fluorescence techniques, and transmission electron microscopy. The block copolymer with the dendritic moiety of a third generation could not be dispersed in water. The block copolymers with the first (PEO-D-Si-1G) and second (PEO-n-Si-2G) generations of dendritic carbosilane blocks formed micelles in an aqueous phase. The critical micelle concentrations of PEO-D-Si-1G and PEO-D-Si-2G, determined by a fluorescence technique, were 27 and 16 mg/L, respectively. The mean diameters of the micelles of PEO-D-Si-1G and PEO-D-Si-2G, measured by dynamic light scattering, were 170 and 190 nm, respectively, which suggests that the micelles had a multicore-type structure. The partition equilibrium constants of pyrene in the micellar solution increased with the increasing size of the dendritic block (e.g., 7.68 x 10(4) for PEO-n-Si-1G and 9.57 x 10(4) for PEO-D-Si-2G). The steady-state fluorescence anisotropy values (r) of 1,6-diphenyl-1,3,5-hexatriene were 0.06 for PEO-D-Si-1G and 0.09 for PEO-D-Si-2G. The r values were lower than those of the linear polymeric amphiphiles, suggesting that the microviscosity of the dendritic micellar core was lower than that of the linear polymeric analogues. (C) 2001 John Wiley & Sons, Inc.