The effect of pressure and temperatue on the micelle formation of dodecylbenzyldimethyl-ammonium chloride solution (The co-operative researches on the fundamental studies of the liquid phase reactions at high pressures)

Abstract

The electrical conductivity of the dodecylbenzyldimethylammonium chloride (DBAC) solution has been measured at high pressure up to 5, 000 atm and at temperature range 25 to 45℃. The critical micelle concentration (c.m.c.) of DBAC increases at high pressure. However, it decreases gradually at higher pressures above 1, 000 atm. The partial molal volume charge, ΔV, for the micelle formation at one atmosphere is calculated from the thermodynamic relationship between c.m.c. and pressure. The value of ΔV decreases gradually with the increase of temperature : -2.cc/mole at 45℃. From the linear relationship between -log (c.m.c.) and 1/T at one atmosphere, it was shown that the value of the partial molal enthalpy change, ΔH, is, constant, -1.28 kcal/mole, at temperature range 25 to 45℃. By using the value of ΔV and ΔH, the partial molal entropy change, ΔS, is calculated to be about +4.5 cal/mole deg.