Self-assembly and rheological behavior of oleic acid-based pseudo-tetrameric surfactants

Traditional tetrameric surfactants exhibit a variety of self-assembled aggregation behaviors and excellent rheological properties. In recent years, the use of non-covalent interactions to construct pseudo-oligomeric surfactants has attracted extensive attention. We constructed dynamic oleic acid-based pseudo-tetrameric surfactants through electrostatic interaction between tetrameric quaternary ammonium salts (3- n -3, n  = 2, 3, 6, 8) and the environmentally friendly sodium oleate. The series of surfactants showed higher viscoelasticity with increasing concentration, which is similar to the traditional tetrameric surfactants. With the addition of the tetrameric salts, the zero-shear viscosity of the original sodium oleate solutions increased by a factor of more than 80,000. The rheological properties can be flexibly modulated by controlling the middle spacer length of the tetrameric quaternary ammonium salt. The wormlike micelles of dynamic oleic acid-based pseudo-tetrameric surfactants will expand the potential applications of ionic liquids in home care products, oil field stimulation fluids, and nanobiotechnology.