Overlap Concentration of Sodium Polystyrene Sulfonate in Solution.

The overlap concentration * of sodium polystyrene sulfonate in water is calculated using multichain atomistic and coarse grained (CG) simulations for a range of chain lengths. Fully atomistic molecular dynamics simulations are carried out for = 32-192 monomers. The CG model was parameterized to match the end-to-end distance from the atomistic simulations at small and allows us to simulate a much larger . Treating the hydrophobic backbone by inclusion of attraction between monomers is an essential addition to the CG model. The simulation * are in agreement with experimental data, yet at *, the chains are not fully stretched, even for as large as 1200. This implies that none of the experimental systems are in the scaling regime and to reach the scaling regime for NaPSS chains much longer than = 1200 are required.