Poly(acrylic acid) (PAA) is widely used as a superabsorbent polymer, a scale inhibitor, and a dispersant.1 For example, the dispersion of CaCO3 slurries with PAA forms nanoparticles that are subsequently used for paper coating. Around 32 billion lbs of CaCO3 per year is produced for this usage. The mechanism of CaCO3 dispersion relies on the electrostatically driven adsorption of the negatively charged PAA onto the cationic surface of the mineral.2 As shown below, the average molecular weight and the polydispersity index (PDI ) Mw/Mn) strongly influence the quality of the dispersion. By decreasing the PDI, less dispersant is needed, and the viscosity is decreased. For this reason, the preparation of monodisperse PAA on a large scale is of high significance