Determination of molecular parameters of linear and circular scleroglucan coexisting in ternary mixtures using light scattering.

A combination of static and dynamic light scattering (SLS and DLS) is applied here to determine molecular parameters for coexisting linear and circular scleroglucan polymers of similar molecular weights, dissolved in water, that is, forming a ternary system. The weight-average molecular weights, M(w), were determined to be 3.2 x 10(5) and 3.9 x 10(5) g/mol for the circular and linear molecules, respectively, whereas the z-average radius of gyration, R(g), was found to be equal to 41 nm for the circular molecules and 136 nm for the linear ones. These values are within a physically reasonable range in view of the heterogeneity of the samples. This study confirms that decomposition of total scattering intensities deduced from the dynamic properties can be used to determine molecular parameters of populations of molecules of equal M(w) but different morphologies present in ternary mixtures.