Behavior of Sulfonated Polystyrene in Dilute Solutions

The current study explores the behavior of sulfonated polystyrene in dilute solutions. Ionizable polymers are often cast from solutions because of their high Tg induced by clustering of the ionic groups. Solution structure however often determines the structure of the polymer films and their properties. Here using molecular dynamics simulations, we probed the conformation of single polystyrene sulfonate at different sulfonation fractions. Sulfonation was varied from 0 to 95% across the transition from ionomer to poly electrolytes. Measurements were carried out in water (ε = 78), THF (ε = 7.5), toluene (ε = 2.8), and cyclohexane (ε = 2.0). The radius of gyration, the static structure factor of the polymer, and counterion condensation were calculated. In high dielectric solvents such as waster, we observe a decrease of counterion and a faster rate of chain collapse than in the lower dielectric solvents such as toluene. In all solvents, the chain's structure is also affected by the sulfonation fraction, where we observe that low sulfonation are slower to collapse fully, if at all.