Transport Properties for Aqueous Solution of Sodium Sulfonate Surfactants. 1. Mutual diffusion measurements: evaluation of the equilibrium parameters for the micellization process.

Isothermal mutual diffusion coeffs. (D) have been measured for binary aq. solns. of sodium alkylsulfonates at 25°C. The diffusion coeff. values drop as the concn. of micelles in the system increases. As the length of the hydrocarbon chain increases, the obsd. drop in D becomes increasingly sharp and shifts to lower concns. When the micellization process is treated as a chem. equil., diffusion coeffs. lead to the calcn. of the thermodn. parameters assocn. no., n, and the equil. const., K. These parameters are briefly discussed in connection with the alkyl chain length of the surfactants.