Surface and thermodynamic parameters of sodium N-acyl sarcosinate surfactant solutions

Surface tension as a function of concentration and temperature was measured for solutions of N-acyl sarcosinates, RCON(CH3)CH2COONa. From the intersection points in the (gamma-log c) curves, the critical micelle concentration (CMC) was determined at 20, 35, 50, and 65 degrees C. Structural effects on the CMC, maximum surface excess, and the minimum area per molecule at the aqueous solution/air interface are discussed. The free energy, enthalpy, and entropy of micellization and adsorption of surfactant solutions also were investigated.