Confinement of polysoaps in nonionic surfactant lyotropic bilayers

We study the confinement of hydrophobically modified polyacrylate (HMPA) in lamellar (L_α) and sponge (L₃) phases of a ternary lyotropic system, comprising n-dodecyl pentaethylene glycol monoether (C₁₂EO₅), hexanol and brine. The unmodified polymer cannot be inserted into the membrane solution, but the confinement of HMPA can be achieved with a sufficient amount of hydrophobe substitution. The resulting stapled polymer structure induces pronounced changes in the phase behavior of the surfactant solution as well as in the membrane properties. Neutron scattering and visual observation were used to obtain phase diagrams and information on membrane properties. We found that the confinement of HMPA 1) induces two new phases: a vesicle-like phase and two coexisting L_α phases, 2) reduces the monophasic L_α, area, and 3) increases the rigidity of the bilayers. The effects of the hydrophobe substitution level and polymer concentration are systematically explored.