EQUILIBRIUM AND KINETIC-STUDIES ASSOCIATED WITH THE BINDING OF SODIUM DODECYL-SULFATE TO THE POLYMERS POLY(PROPYLENE OXIDE) AND ETHYL(HYDROXYETHYL) CELLULOSE

Equilibrium measurements associated with the binding of sodium dodecyl sulfate (SDS) with the polymers poly(propylene oxide) (PPO) and ethyl(hydroxyethyl)cellulose (EHEC) have been carried out using emf and isothermal titration calorimetry. Gel filtration was also used to study the SDS/PPO system. In the SDS/PPO system, ''free'' micelles occur in solution well before the polymer becomes fully saturated with bound surfactant aggregates. A quick calculation shows that the SDS/PPO complex consists of one micellar-type aggregate bound to two to three polymer molecules. In the SDS/EHEC system, a gel-like polymer network is formed, which with further addition of SDS breaks down to a ''string of beads'' like the complex involving one polymer molecule and several micellar-type aggregates. In this system, free micelles occur in solution only after the polymer becomes fully saturated with bound aggregates. We have also carried out ultrasonic relaxation measurements on both systems in an attempt to study the kinetics of the monomer surfactant reversible arrow bound aggregated surfactant exchange process.