HIGHLY ORGANIZED MULTILAMELLAR STRUCTURES FORMED BY POLYELECTROLYTE NETWORK - SURFACTANT COMPLEXES. Yu. Khandurina, V. Rogacheva, A. Zezin, Polymer Chemistry Department, Moscow State University, Russia

The structure of polymer-surfactant complexes based on cross-linked polyelectrolytes and oppositely charged surfactants of various nature was studied by wide and small-angle X-ray and small-angle neutron scattering. Such complexes are formed as a result of interaction between slightly cross-linked highly swollen polyelectrolyte gel and surfactant in aqueous media. The transfer of surfactant ions into the network proceeds as a frontal heterogeneous cooperative reaction followed by the localized collapse of the initial gel and the formation of "core-shell" type systems, in which weakly swollen polymer-surfactant complex "shell" coexists with highly swollen surfactant free gel interior. The complexes contain equimolar amounts of surfactant ions and ionized polyelectrolyte units and are stabilized by both electrostatic and hydrophobic interactions.

The X-ray diffraction data allow to represent the polyelectrolyte surfactant complex structure as a system of surfactant lamellas inserted into the oppositely charged network. The formation of these constructions occurs by the intergrowth of surfactant lamellas into the gel interior and is accompanied by a macroscopic orientation of multilamellar structure. Thus, the processes under investigation are closely related to selfassembly phenomena in complex macromolecular systems. The parameters of lamellas and internal lamellar structure of polycomplexes depend on the nature of polymer network and surfactant (aliphatic chain length and ionic group nature) and on the external conditions (temperature, pH, water content, etc.). Aliphatic surfactant radicals of the sufficient length produce a crystalline hexagonal packing inside lamellar aggregates.