Robert Lee Wells

Phase behavior and network formation in a cationic surfactant-fatty alcohol-water system

Optical microscopy and differential scanning calorimetry were used to study the behavior of dilute aqueous systems containing mixtures of a long-chain cationic surfactant and long-chain fatty alcohols. Both alcoholrich particles with a lamellar structure and crystalline fibers containing considerable surfactant were observed, the fibers becoming more prevalent with decreasing values of the alcohol-to-surfactant ratio r. For values of r exceeding about two, separate fibrous and particulate regions were seen, the latter forming continuous networks throughout individual samples and hence contributing to the viscoelastic properties known to characterize these formulations. Studies of system behavior as a function of temperature showed that melting temperatures of the fibers and particles were about 55 C and 60 C, respectively.