Analysis of the diffusion in pseudobinary systems: Applications of Gouy interferometry parameters lo polydisperse systems

The theory of diffusion in n-component. systems has been applied to study t he mutual diffusion of polydisperse polymeric systems. General relations fo r n-component systems have been obtained for the experimental Gouy paramete rs, D-A and Q(0). Through the use of the Flory equation for diffusion coeff icients of monodisperse polymers, the expressions of D-A and Q(0) at infini te dilution, D-A(infinity) and Q(0)(infinity), for a general molecular weig ht distribution have been obtained. These relations have been used to analy ze the effect of polydispersity on Gouy diffusion parameters, and the relat ive information content of Q(0)(infinity) is stressed. A procedure is sugge sted to determine the molecular weight and to estimate the results of the f ractionation through the Gouy interferometry. The results of this analysis have been applied to polyethyleneglycol, polyacrylic acid, and sodium polya crylate diffusion data.