Structure and dynamics of microemulsions. Part 1.—Effect of additives on percolation of conductance and energetics of clustering in water–AOT–heptane microemulsions

Percolation of conductance in the H2O–AOT–heptane system as a function of water content at constant temperature and with variation of temperature at constant composition, in the presence of a large number of additives, are reported. Non-conjugated hydroxy bile salts enhanced percolation whereas cationic surfactants, salts and cholesterol suppressed the process. Various other additives had no effect or assisted the process. The conductance results obeyed the scaling law. Viscosity measurements implied association of microdroplets (cluster formation) during percolation. The energetics of clustering were evaluated by the determination of the dispersion concentration dependent percolation threshold at different temperatures. The enthalpy and entropy of clustering compensate.