PROBE DIFFUSION IN THE PRESENCE OF NONIONIC AMPHIPHILES - TRITON X-100

We used quasi-elastic light scattering spectroscopy to measure the mutual diffusion coefficient D(m) of Triton X-100 micelles and the diffusion coefficient D(p) of polystyrene latex probe particles in Triton X-100: water solutions, for Triton X-100 concentrations up to 100 g/L. From the zero-concentration limits and linear concentration (of surfactant) dependences of D(p) and D(m), at 298 K we obtain a hydrodynamic radius of 45 angstrom for a Triton X-100 micelle. By using both mutual and optical probe diffusion methods, we were able to determine the amount of surfactant in a typical micelle [(65 +/- 5) X 10(3) Da, corresponding to a mean aggregation number N almost-equal-to 100] and the hydration of a micelle (2.6 g(H2O)/g(TX-100)).