How does the chain extension of poly (acrylic acid) scale in aqueous solution? A combined study with light scattering and computer simulation

This work addresses the question of the scaling behavior of polyelectrolytes in solution for a realistic prototype. We show results of a combined experimental (light scattering) and theoretical (computer simulations) investigation of structural properties of the sodium salt of poly (acrylic acid) (Na-PAA). Experimentally, we determined the molecular weight (MW) and the hydrodynamic radius (RH) by static and dynamic light scattering for six different Na-PAA samples in aqueous NaCl-containing solution (0.1–1 mol/l) of polydispersity DP between 1.5 and 1.8. On the computational side, three different variants of a newly developed mesoscopic force field for Na-PAA were employed to determine RH for monodisperse systems of the same MW as in the experiments. The force field effectively incorporates atomistic information and one coarse-grained bead corresponds to one PAA monomer. We find that RH matches with the experimental data for all investigated samples. The effective scaling exponent for RH is found to be ar...