A series of amphiphilic block copolymers, polymethyl methacrylate (PMMA)-b-poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA), were synthesized by atom transfer radical polymerization (ATRP) method. Surface tension, dynamic light scattering (DLS), transmission electron microscope (TEM), and atomic force microscopy (AFM) studies were performed to investigate the aqueous micellar behavior of these block amphiphiles. At a fixed degree of polymerization (DP) of PMMA block (DP = 55), the PDMAEMA block length was found to have a significant influence on the critical micelle concentration (cmc) values and hydrodynamic size of aggregates. An increase in the DP of PDMAEMA from 11 to 337, resulted in a decrease in the cmc from 1.44 x 10(-5) to 5.81 x 10(-7) M (a factor of almost 24.8), and a decrease in the Z (2R(h)) from 85.5 to 15.5 nm (pH = 4), respectively. TEM and AFM results indicated that by changing the soluble block lengths, spherical, short rod, crew-cut, vesicles or large aggregates can be observed in the solution. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012