Properties of vesicles formation of single-chain branched carboxylate anionic surfactant in aqueous solutions

A branched anionic surfactant 3, 5, 7-trimethyl decanol polyoxyethylene ether carboxylate (AEC(7)-Na) was successfully synthesized with the purity of 91% by one step oxidation process. The products were characterized by Fourier transform infrared (FT-IR) spectra and nuclear magnetic resonance spectroscopy ((HNMR)-H-1). The aggregation properties of raw material 3, 5, 7-trimethyl decanol polyoxyethylene ether (AEO(7)), alcohol ether carboxylic acid (AEC(7)-H) and carboxylate (AEC(7)-Na) in aqueous solution have been studied by surface tension, electrical conductivity, contact angle, steady-state fluorescence and transmission electron microscopy. AEC(7)-Na shows excellent surface properties with gamma(cmc) being 27.19 mN/m owing to the presence of branched chain and good wetting ability on the low energy surface which was testified to be no match for AEO(7). In low concentration, acid soap dimers were produced in AEC(7)-Na aqueous solutions and with increasing concentration, vesicles were formed spontaneously below the CMC which was known to be thermodynamically stable. In addition, vesicles to micelle transition could occur nearby the CMC. It is unique for single-tailed alcohol ether carboxylate to form vesicles. (C) 2017 Published by Elsevier B.V.