The effect of poly(N,N-dimethylacrylamide) on the lamellar phase of Aerosol OT/water

The effect of a water-soluble uncharged polymer on the stability of the lamellar phase of the Aerosol OT (AOT)/water system is studied. The lamellar phase still exists when water is replaced by an aqueous solution of poly(N,N- dimethylacrylamide) (R_gƼ᎒² Å). Since the coil dimensions are (much) larger than the thickness of the water layers (d_wᅣ Å), the polymer molecules do not enter the lamellar phase. Instead segregation in small domains occurs, and in equilibrium with the AOT-rich phase another separate phase containing the polymer is formed. The polymer-rich phase exerts an osmotic pressure that reduces the water content in the AOT-rich phase, and by compression the repeat distance is reduced.