Interfacial tension between demixed symmetrical polymer solutions: Polystyrene-poly(dimethylsiloxane)-propylbenzene system

Interfacial tension between demixed symmetrical polymer solutions of polystyrene-poly(dimethylsiloxane)-propylbenzene was measured as a function of temperature near the critical point at a fixed critical temperature (60.0°C) for molecular weights from 9000 to 1.0 × 10⁵. The interfacial tension increased as the molecular weight was lowered. The order of magnitudes of the interfacial tension was in good agreement with the theoretical prediction proposed previously by Nose. The critical exponents β and μ were estimated as near the values found for ordinary binary mixtures or liquids. Cloud point curves and coexistence curves were also obtained and properties related to incompatibility were also briefly discussed.