Molecular Mass Dependence of Interfacial Tension in Complex Coacervation

Although an important design parameter in complex coacervation, the molecular mass dependence of the interfacial tension far from the critical point has yet to be studied in detail. Here we perform careful experiments supplemented with coarse-grained molecular dynamics simulations to elucidate this dependence. Subsequently, we derive the dependence and show that it is independent of the functional form of the non-ideal interactions assuming that (1) the concentration of polymer is the supernatant is negligible, a good assumption far from the critical point, and (2) that the non-ideal interactions have no explicit molecular mass dependence.