Influence of Salts on Morphology of Structures in Surfactant-Polymer Solutions Explored by Coarse Grained Dynamic Simulation

In this study, a coarse-grained molecular dynamic simulation was employed to test the influence of salts in morphology of structures in surfactant-polymer solutions. The surfactant was cetyltrimethyl ammonium chloride (CTAC) and the polymer was polyacrylamide (PAM). Six different salt concentrations were studied in the mixed surfactant-polymer solutions, and pure surfactant solutions with salts were also tested as control groups. By analyzing the shapes of micelles and the CTA+ aggregation number of micelles, we noted that the proper salt concentration can facilitate the formation of large micelles. In too high or too low salt concentration solutions only spherical or short rodlike micelles exist. The existence of PAM can also facilitate the formation of large micelles because polymers act as “bridges” and increase the probability of touch and coalescence of micelles.