PATTERNS OF PHASE-BEHAVIOR IN POLYMER AND AMPHIPHILE MIXTURES

A relatively unexplored area of research, the phase behavior of amphiphile and polymer mixtures in water is examined as a function of temperature and composition. The miscibility of ethoxylated alcohol amphiphile [CH3(CH2)i-1O(CH2CH2O)(j)H] and poly(ethylene oxide) in water decreases strongly upon increasing the strength of the amphiphile (i + j) or increasing the molecular weight of the polymer. As the amphiphile is stretched from the weakly associating C4E1 to the micelle-forming surfactant C-8E4, the separate upper and lower miscibility gaps of C4E1/polymer/water collide and merge to form a continuous two-phase region from low to high temperatures. A similar trend is observed upon increasing polymer molecular weight. Some of the phase behavior patterns resemble those found for mixtures of two polymers in a solvent.