Dielectric properties of some ethoxylated primary amines in nonaqueous medium. Effect of added alcohol on dipole moment and CMC values

The dielectric relaxation behaviour of primary decylamine, dodecylamine, he xadecylamine and octadecylamine ethoxylates in benzene solutions has been s tudied over the frequency range 0.2 to 18 GHz at 20, 30 and 40 degrees C. T he critical micelle concentration (CMC) values of these surfactants have be en determined from the dipole moment-concentration plots through the least- squares regression analysis. The effects of the hydrophobic chain length (R ), the hydrophilic polyoxyethylene (POE) chain length and added butanol on the determined CMC values, have been investigated. The thermodynamic parame ters (Delta F, Delta H and Delta S) which represent the change of free ener gy, activation energy and entropy upon micelle formation, were obtained and discussed in terms of the molecular behaviour.