Size and shape of the molecules in artificially branched polystyrene

Abstract

A sample of copolymer of divinylbenzene and styrene has been prepared and fractionated. Using the techniques of light scattering and viscometry the relations between the molecular size, intrinsic viscosity, and weight‐average molecular weight have been determined. The results may be interpreted in terms of the already existing theory of branched polymers. The curve of logarithm of intrinsic viscosity plotted against logarithm of molecular weight shows clearly the effect of branching in the polymer chains, the intrinsic viscosities of the higher molecular weight fractions being low compared to those of pure polystyrene. The mean square radius of the molecules as determined by light scattering shows similar effects, though complications obscure the picture. Some of the other solution properties of the branched materials also are peculiar. The results show that the semiquantitative determination of branching is possible in this way.