Universality of Osmotic Equation of State in Star Polymer Solutions

We experimentally measure the osmotic pressures of linear polymers and three-, four-, and eight-arm star polymers in a good solvent via membrane osmometry. These results reveal that the osmotic equations of state in the star polymer solutions are universally described by the same scaling function that describes linear polymer solutions. This universality is achieved by canceling increasing overlap concentrations and decreasing osmotic pressure, owing to the increased arm number. We further clarify the molar mass and arm number dependencies of the gyration radius and interpenetration factor, ensuring universality in star polymer solutions.