Complex amphiphilic polymers were synthesized via core-first polymerization followed by alkylation-based grafting of poly(ethylene oxide) (PEO). Inimer 1-(4'-(bromomethyl)-benzyloxy)-2,3,5,6-tetrafluoro-4-vinylbenzene was synthesized and subjected to atom transfer radical self-condensing vinyl polymerization to afford hyperbranched fluoropolymer (HBFP) as the hydrophobic core component with a number-averaged molecular weight of 29 kDa and polydispersity index of 2.1. The alkyl halide chain ends on the HBFP were allowed to undergo reaction with monomethoxy-terminated poly(ethylene oxide) amine (PEOx-NH2) at different grafting numbers and PEO chain lengths to afford PEO-functionalized HBFPs [(PEOx)(y)-HBFPs], with x = 15 while y = 16, 22, or 29, x = 44 while y = 16, and x = 112 while y = 16. The amphiphilic, grafted block copolymers were found to aggregate in aqueous solution to give micelles with number-averaged diameters (D-av) of 12-28 nm, as measured by transmission electron microscopy (TEM). An increase of the PEO:HBFP ratio, by increase in either the grafting densities (y values) or the chain lengths (x values), led to decreased TEM-measured diameters. These complex, amphiphilic (PEOx)(y)-HBFPs, with tunable sizes, might find potential applications as nanoscopic biomedical devices, such as drug delivery vehicles and F-19 magnetic resonance imaging agents. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3487-3496, 2010