A NONIONIC MICROEMULSION WITH ADSORBING POLYELECTROLYTE

Structure and interactions were investigated when small amounts of a h ydrophobically modified poly(sodium acrylate) (HMPA) were added to a d roplet microemulsion-lamellar system comprising nonionic surfactant. A s demonstrated by small angle neutron scattering and NMR self-diffusio n the aggregate structure was unaffected by HMPA, accounting for a tem perature shift in the phase boundaries. Viscoelastic gels are formed i n the droplet microemulsion-HMPA mixtures above a certain polyelectrol yte concentration. HMPA is soluble in the lamellar phase at high dilut ion. Upon increasing the bilayer concentration a phase separation is i nduced where excess bilayers form a separate phase. The lamellar phase with HMPA collapses when adding salt, probably as a result of bridgin g. A viscous microemulsion solution can be transformed to a viscoelast ic gel upon increasing the temperature. A dramatic change in surfactan t aggregate structure is responsible for this spectacular effect.