Near-monodisperse diblock, triblock, and multiarm star-block copolymers of polystyrene (PS) and poly(4-tert-butylstyrene) (PtBS) were synthesized using anionic polymerization techniques. Selective sulfonation of PS blocks by using the complex of sulfur trioxide (SO3) and triethyl phosphate (TEP) in 1,2-dichloroethane (DCE), followed by neutralization with sodium methoxide, was performed to yield the corresponding well-defined neutral/ionic block copolymers of sodium poly(styrenesulfonate) (NaPSS) and PtBS. A number of techniques including matrix-assisted laser desorption ionization time-of-flight mass spectroscopy (MALDI/TOF/MS), Fourier transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance spectroscopy (NMR) were employed to characterize these materials.