Poly(acrylamide/sodium acrylate/N-dodecyl acrylamide)s [poly(AM/NaAA/C12AM)s] with different hydrophobic microblock lengths (NH's) were prepared by the micellar copolymerization of acrylamide and sodium acrylate with a low amount of N-dodecyl acrylamide (0.2 mol %), and the molecular structure was characterized by Fourier transform infrared spectroscopy, 1H-NMR, and static light scattering. A combination of experiments involving viscosity measurement, fluorescence, and conductometry was applied to investigate the effect of NH on the interaction strength and binding capacity between poly(AM/NaAA/C12AM)s and C12H25SO4Na [sodium dodecyl sulfate (SDS)]. The viscosity, I3/I1 (the intensity ratio of the third vibrational band to the first band of pyrene molecules), and conductivity of the mixed system of copolymers with SDS all had different variation trends with the concentration of SDS. The binding capacity of the copolymers with SDS was calculated according to quantitative differences between the critical micelle concentration of the pure SDS solution and the mixed system. All of the results show that the interaction strength of SDS with the copolymers rose, and the binding capacity decreased with increasing NH. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40633.