Chapter 9 - Limiting Viscosity Number (Intrinsic Viscosity) and Related Properties of Very Dilute Solutions

Abstract

The properties of very dilute polymer solutions are determined by the conformational states of the separate polymer molecules, which may be expressed in molecular dimensions (e.g., the mean square end-to-end distance of a polymer molecule) or in the limiting viscosity number (intrinsic viscosity). This chapter deals mainly with the properties of very dilute polymer solutions. It is under these conditions only that isolated linear polymer molecules can be studied. An isolated linear macromolecule generally tends to assume a random coil configuration. Only for very stiff polymers a rod-like configuration is assumed. Several types of measurements can be used to determine the dimensions of the random coil configuration. Conversely, if the appropriate relationships have been established, the same measurements can be used to determine the average molar mass of a given polymer. The principal types of measurements on very dilute polymer solutions are viscosity measurements, light scattering measurements, small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS), and osmotic pressure measurements. This chapter also considers the quantitative relationships of the isolated macromolecule and of the macromolecule in very dilute solutions. Furthermore, it describes the limiting viscosity number, which is also known as intrinsic viscosity.