Flow injection analysis estimation of diffusion coefficients of pauci‐ and polydisperse polymers such as polystyrene sulfonates

Flow injection analysis, often used for determination of diffusion coefficients of nonpolymeric substances, has now been applied to the characterization of pauci‐ and polydisperse polymers in solution. A relative method was found useful for obtaining moderate quality evaluations of diffusion coefficients and related parameters of polymers. The width at half‐height W1/2 of the trace peak is found to be proportional to the number average molecular weight M̄n of pauci‐ and polydisperse polymers, allowing estimation of M̄r and diffusion coefficients. For sodium polystyrene sulfonates at substantially infinite dilution in 1.0 g L−1 Na2SO4, a linear relation has been observed between the logarithms of the molecular weight M̄n and the mean diffusion coefficient D in the M̄n range of 1000–90,000 g mol−1 or the D range of 30 × 10−7 to 2 × 10−7 cm2 s−1.