Dynamics of the swollen lamellar phase

We investigate the dynamical behavior of lamellar phases in ternary amphiph ilic systems of water, oil and amphiphile. The interaction between the amph iphilic monolayers is described by the steric interaction due to thermal fl uctuations for uncharged, and by electrostatic interactions for charged sys tems. The dynamics of the system is determined by the hydrodynamics of the fluid layers. The basic parameters of our model are the viscosities of the two solvents, the average thicknesses of the oil and water layers. and the bending rigidity. The model allows to consider different monolayer interact ions across the oil and water lavers. Relaxation rates are calculated for a rbitrary wave vectors parallel and perpendicular to the average monolayer p lane. We find that there is a quite complex crossover behavior from a q(par allel to)(2) law for small parallel wave vectors to a q(parallel to)(3) law for large q(parallel to). We discuss the relevance of our result for the i nterpretation of dynamic light-scattering and neutron-spin-echo experiments for these systems.