Uniform polymeric nanospheres comprised of hydrophilic cores and hydrophobic coronas were prepared by dispersion free radical copolymerization of acrylamide with poly(tert-butyl methacrylate) macromonomer (PtBMA) in ethanol/water mixed solvents, and the effects of cross-linker addition on the nanosphere size were investigated. Chemical analysis by electron spectroscopy confirmed that hydrophobic PtBMA chains grafted to the nanosphere surfaces. Changes in concentrations of the monomers and the cross-linker controlled the hydrodynamic diameter of the nanospheres (140-540 nm).