CHARACTERIZATION OF LINEAR COPOLYMERS BY METHODS SENSITIVE TO THE REFRACTIVE-INDEX INCREMENT

For linear copolymer molecules, the refractive index increment depends on the chemical composition of the molecules. However, the polydispersity in chemical composition of the sample introduces a great complexity in the data analysis in order to obtain a true molecular weight distribution. Even when the mean chemical composition does not depend on the output of an instrument depends quadratically on the refractive index increment of the sample, such as in a light-scattering measurement. For that purpose, the light-scattering expressions are written in terms of polydispersity in chemical composition, which in turn is modeled using linear copolymerization equations. The microstructure effects, which are related to the order in which two different kinds of monomers appear along the chain, are not as yet taken into account in this approach.