Assessment of Branching in Polymers by Size Exclusion Chromatography with Light Scattering, Viscosity, and Refractive Index Detection

Abstract

Abstract The objective of this work was to assess the methods for determining the degree of long-chain branching in polysaccharides by light scattering and viscosity techniques in combination with size exclusion chromatography (SEC). The samples used were branched dextrans and the reference linear polymers were pullulans. The first method involved determining the ratio of the radii of gyration for branched and linear polymers having the same molecular weight by SEC with multi-angle laser light scattering (MALLS). In the second and third methods, branching was determined by the ratio of the intrinsic viscosities (IV) of branched and linear polymer having the same molecular weight for the SEC slices as well as for the whole polymer, using different values for the structure and solvent factor, e. The average frequencies obtained for long-chain branching for the whole polymers by light scattering, as well as by viscometry and for the slices by viscometry, agreed well with each other and with those reported fr...