Effect of NaCl on Aggregation Number, Microviscosity, and Cmc ofN-Dodecanoyl Amino Acid Surfactant Micelles

摘要: Microviscosity, micellar aggregation number (N), and critical micelle concentration (cmc) were determined in solutions of sodiumN-dodecanoyl-glycinate (Lau-Gly), -valinate (Lau-Val), -leucinate (Lau-Leu), -phenylalaninate (Lau-Phe) as a function NaCl using fluorescent probes (auramine, pyrene). The microviscosity increased with increasing reached saturated value. In addition, two breakpoints found on the curve vs by comparison data ofNand solution viscosity. first second explained, respectively, beginnings growth intermicellar interaction. value ofNincreased steeply above breakpoint viscosity began to increase at breakpoint. concentrations order Lau-Phe < Lau-Leu Lau-Val ∼ Lau-Gly. absolute slope Corrin–Harkins plot cmc was smaller for Lau–Leu –Phe than Lau-Gly -Val. Larger values (1.2 2), which suggested contribution salting out effect cmc, observed high interaction occurred lower size amino acid residue when surfactant larger valine; that is, hydrophobicity dominant factor rather steric hindrance.