The gel to coagel phase transition of monoglyceride−water systems has been studied by nuclear magnetic resonance and differential scanning calorimetry. It is shown that the molecular arrangements within the bulk β-crystal of monoglyceride and the coagel phase are identical. The mobility of the glycerol backbone is high in the gel phase. On a decrease of temperature the mobility drops and then crystallization of the gel into a coagel phase takes place where hydrogen bonds among the glycerol groups are formed. A prerequisite for this is that d and l isomers of monoglyceride rearrange within the bilayers through chiral discrimination. The gel to coagel transition can be discussed in the frame of the Avrami theory of crystallization kinetics. The values of the Avrami exponent indicate a transition from a 2-dimensional to a 3-dimensional crystal growth on increasing the monoglyceride concentration. In the case of a 2-dimensional crystal growth the phase transition is diffusion controlled. Moreover, on applying shear to the gel phase, the phase transition evolves from a random to a spontaneous nucleation mechanism.

The structure of AOT microemulsions in various bulk solvents is investigated by SAXS and conductivity measurements. The intermicellar interactions are analyzed with the sticky hard-sphere model taking into account the discret nature of the solvent. A model is proposed to explain the decrease in the interdroplet attractions with the increase of volume fraction of reverse micelles. It is based on the existence of depletion forces between reverse micelles. It allows the determination of a theoretical relation between the stickiness parameter and the reverse micelle volume fraction which is compared to experimental data. The percolation threshold of reverse micellar systems is then qualitatively determined in three different solvents.

The decreases of the exchange micellar rate constant, determined from stopped flow kinetic study, and of the sticky parameter, determined by small angle X-ray scattering, with the water volume fraction are strongly correlated. This phenomenon is explained according to the contact value of the micelle−micelle correlation function and the surfactant monolayer rigidity. It is shown that the attractive interactions govern the decrease of the exchange process with the increase in the number of droplets.

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