The rheological behavior of sodium dodecyl sulfate/N-hexylamine aqueous solution at high concentrations

Abstract In order to study the interaction between the sodium dodecyl sulfate (SDS)/ n-hexylamine (NHA) composite aqueous solution, the supramolecular system had been constructed at the optimal molar ratio of 1:1 at high mass concentration. Based on the experimental results, supramolecular system formation mechanism was proposed according to the determination of its rheology, Cryo-TEM, Dynamic light scattering (DLS). SDS and NHA form vesicles via hydrogen bonding and electrostatic repulsion. The phase behavior of the system transforms from unilamellar vesicles under relative low mass concentration to multilamellar vesicles when the mass concentration increases to 200mM. Meanwhile, temperature and inorganic salts were used to observe the effects of hydrogen bonding and electrostatic repulsion on vesicles. When temperature rises to 55℃, the vesicle basically disappears. When inorganic salt concentration reaches 150mM, the vesicle gradually transforms into fibrous structure. From the perspective of fluidity state, the influence of temperature on vesicles is more than that of inorganic salts.