Thermodynamic and hydrodynamic properties of dilute solutions of cyclic and linear polystyrenes

Abstract

The thermodynamic and hydrodynamic properties of cyclic and linear polystyrenes, ranging from 10000 to 180000 molecular weight, in dilute solutions of cyclohexane have been measured by small-angle neutron scattering (SANS) and dynamic light scattering. The diffusion coefficient D(c) was measured at θA2=0 as a function of concentration c. The hydrodynamic radii were determined and found to be slightly smaller for cyclic than for linear macromolecules. The slope kD, defined by D(c) = D(0)(1 + kDc), was found to be negative and was, within experimental error, independent of molecular architecture. The molecular weight dependence of the radius of gyration, the hydrodynamic radius, and kD is discussed.