Kinetic pathways of multiphase surfactant systems

Relaxation following a temperature quench of two- (L-alpha and L-3) and thr ee-phase (L-alpha, L-3 and L-1) samples has been studied in a sodium dodecy l sulfate-octanol-brine system. In the three-phase case we have observed sa mples that ale initially mainly of the sponge phase, with lamellar and mice llar phases on the top and bottom of the sample, respectively. Upon decreas ing 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 nu cleation 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 int o a two-phase L-alpha-L-3 sample. We offer possible explanations for some o f these observations in the context of a general theory for phase kinetics in systems with one fast composition variable and one slow.