Osmotic Pressure of Semidilute Solutions of Branched Polymers

Abstract

Osmotic pressures for branched polymers in a good solvent were measured over a wide range of concentrations. Two types of branched polymers, star-shaped poly(α-methylstyrene)s having three branches and comb-shaped polystyrenes having 15—16 branches, were studied. The data were analyzed using the scaling law. The difference in the reduced osmotic pressure between star-shaped polymers having three branches and the corresponding linear polymers results from the difference in radii of gyration. In branched polymers having many branches, there is a region from which the segments of other molecules are excluded as a result of high segment density.