Nonionic water-in-oil (w/o)−microemulsions of the type water/c-hexane, n-hexane/Igepal were examined by SANS in both shell and core contrast. Variation of the water to surfactant ratio W 0 in the droplet regime yields a linear relation between W 0 and the droplet water core radius and R/nm = 0.19 W 0 + 0.70. Small angle neutron scattering (SANS) data for W 0 = 10 samples show that droplet aggregation occurs with a fractal dimension of D ≤ 1.3 as a percolation-like transition is crossed by decreasing temperature. Data analysis and model calculations, done in both q and r space, are consistent with the formation of linear aggregates of discrete spherical droplets.

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A percolation transition in microemulsions can be induced by high electric fields. We report on the dynamics of the processes. Comparison of time‐resolved conductivity, birefringence and light scattering measurements gives information on the structure changes. The differences of ionic and nonionic microemulsions are emphasized.