Temperature studies of coacervating cationic soap solutions

The micellar molecular weights (MMW) and the critical micelle concentration (CMC) of the homogeneous phase of the cationic coacervating soap system, Hyamine-1622, as a function of NaCl concn and temp were determined from light scat-tering and refractive index measurements. At constant temp, an overall two-stage growth proc-ess is indicated in this system. At low NaCl concn, the micelle grows to a limiting isotropic structure. At higher NaCl concn, the micellar growth is an exponential function of the NaCl concn. Temp studies of the CMC provide the basis for calculating values of the heats of micel-lization, ΔHm in a limited range of NaCl concn (0-0.06M). The temp dependence of the MMW at fixed NaCl concn in the range of 17-47 C is an exponential function and plots of log (MMW) vs. 1/T give straight lines with positive slopes. At low NaCl concn (0-0.8M), where there is an effective charge on the micelles, these slopes are small. At high NaCl concn, where the micelles approach zero effective charge (theta conditions), the slopes increase abruptly and remain approx constant over a wide range of NaCl concn (0.08-0.24M).