Abstract: The diffusion behavior of polystyrene with narrow molecular weight distribution at 20℃ in 1, 4-dioxane was investigated by the photon correlation spectroscopy. The cumulant method was employed for the analysis of the intensity-intensity autocorrelation function measured over a wide range of the scattering vector. The diffusion coefficient D was determined as the function of concentration Cin the molecular weight range of 3. 0×10⁴-1. 20×10⁶. In a low concentration range, D was found to be linearly dependent on C, which has been found for some other systems. The dependence of Don molecular weight at infinite dilution can be written as an empirical formula D₀=k_DM_M^-γ, the exponent γ(0. 576 ±0. 01) is in good agreement with the result of the scaling theory.

Key words: Molecular diffusion, Polystyrene, Dynamic light scattering