PHASE-SEPARATION IN CONCENTRATED MIXTURES OF POLYMERS AND SURFACTANTS

The phase behaviour of concentrated mixtures of non-ionic polymers and surfactants has been studied and compared with a simple theory for de pletion of polymers from the surface of a colloidal particle. In syste ms where there is no association between the polymer and surfactant, p hase separation occurs to give polymer-rich and surfactant-rich phases . Where there was an initial association between the polymer and surfa ctant, separation occurred at higher concentrations. The phase separat ion has been treated as depletion flocculation, a theory for which giv es the approximate distributions of polymer and surfactant in each pha se. The effects of temperature, electrolyte and hydrocarbon chain leng th of the surfactant can be understood by comparison with their effect s on the cloud points of the pure surfactants.