Block copolymers of very hydrophilic poly(N-hydroxyethyl acrylamide) (PHEAA) with polystyrene (PS) were successfully synthesized by sequential atom transfer radical polymerization of ethyl acrylate (EA) and styrene monomers and subsequent aminolysis of the acrylic block with ethanolamine. Quantitative aminolysis of poly(ethyl acrylate) (PEA) block yielded poly(N-hydroxyethyl acrylamide)-b-polystyrene in well-defined structures, as evidenced by Fourier transform infrared spectroscopy (FTIR) and H-1-NMR spectroscopy techniques. Three copolymers with constant chain length of PHEAA (degree of polymerization: 80) and PS blocks with 21, 74, and 121 repeating units were prepared by this method. Among those, the block copolymer with 21 styrene repeating units showed excellent micellation behavior in water without phase inversion below 100 degrees C, as inferred from dynamical light scattering, environmental scanning electron microscopy, and fluorescence measurements. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 2684-2689, 2013