Micellization of decyldimethylbenzylammonium chloride at various temperatures studied by densitometry and conductivity

The critical micelle concentration (cmc), ionization degree of micellization, β, and standard free energy of micellization, ΔG0m, of decylbenzyldimethylammonium chloride in aqueous solution at 15, 25, 35, 45 and 55°C have been estimated from conductivity data. A shallow minimum of the cmc value appears at around 35°C. The apparent molar volumes of the monomeric and micellized surfactant were estimated from density data measured at 15, 25 and 35°C. It is suggested that release of water molecules from the hydration shell of the counter-ions may be an important contribution to the observed apparent expansion of the surfactant upon micellization.