Ultracentrifugal study of a non-ionic surface-active agent in D2O

The micellar weight of a non-ionic surface-active agent, dodecyl hexaoxyethylene glycol monoether, in D2O has been determined by the Archibald method of approach to sedimentation equilibrium as a function of temperature. The apparent micellar weight remained constant in the temperature range 5 to 15°C at ca. 50,000 and then increased rapidly with temperature to 840,000 at 35.0°C. Examination of the system by sedimentation velocity and viscosity experiments suggested that changes in the size of the kinetic units occurred as a function of temperature and concentration.