Aging mechanism of unsaturated long-chain amidosulfobetaine worm fluids at high temperature

Both fundamental and technological research interests have highlighted in recent years a remarkable growing focus on surfactant wormlike micelles. Nevertheless, long-term thermal stability, as well as the corresponding aging mechanism of viscoelastic worm fluids was rarely examined. We report for the first time the high-temperature aging effect on wormlike micellar solutions formed by an unsaturated C-22-tailed amidosulfobetaine surfactant in the absence and presence of a reducer, by means of rheological methods, cryo-TEM observations, IR and H-1 NMR measurements. It was found that the aging effect mainly resulted from the degradation of the carbon-carbon double bond in the surfactant tail rather than its amido head group; and the addition of a small amount of reducing agent could effectively improve thermal stability of the worm fluids.