Kinetic pathways of multiphase surfactant systems

Relaxation following a temperature quench of two- (L-alpha and L-3) and three-phase (L-alpha, L-3 and L-1) samples has been studied in a sodium dodecyl sulfate-octanol-brine system. In the three-phase case we have observed samples that ale initially mainly of the sponge phase, with lamellar and micellar phases on the top and bottom of the sample, respectively. Upon decreasing the temperature, most of the volume of the sponge phase is replaced by the lamellar phase. During equilibration we have observed three regimes of behavior within the sponge phase: (i) first there is disruption in the L-3 texture, then (ii) after the sponge phase homogenizes there is a L-alpha nucleation regime; finally (iii), a bizarre plume connects the L-alpha phase with the L-1 phase. The relaxation of the two-phase sample proceeds instead in two stages. First L-alpha drops nucleate in L-3 forming an onion "gel" structure. Over time the L-alpha structure compacts while equilibrating into a two-phase L-alpha-L-3 sample. We offer possible explanations for some of these observations in the context of a general theory for phase kinetics in systems with one fast composition variable and one slow.