A pH, thermal and light triple-stimuli responsive micellar solution formed by a cationic surfactant and -hydroxycinnamic acid.

Controlling the viscoelastic characteristics of wormlike micelles is of great significance to both basic theory and practical applications. In this article, a novel multi-stimuli responsive wormlike micellar solution was prepared by mixing cationic surfactant 3-hexadecyloxy-2-hydroxypropyltrimethylammonium bromide (RHTAB) with -hydroxycinnamic acid (OHCA). Rheological studies, nuclear magnetic resonance (H-NMR) spectroscopy, UV-vis spectroscopy, and cryogenic-transmission electron microscopy (cryo-TEM) were utilized to investigate the wormlike micellar system's multi-responsive activity. The results showed that the self-assembled structure and viscoelasticity of the mixed system could be regulated by pH, temperature, and light irradiation. With the increasing -OHCA concentration, of the mixed solution increases first and then decreases and the turning point is presented at 30 mM -OHCA, indicating the transformation of spherical micelles to wormlike micelles, and then to short micelles. The microstructure of the mixed systems could be reversibly altered by adjusting the pH between 6.41 and 3.90, which was ascertained by cryogenic-transmission electron microscopy (cryo-TEM). The relationship of temperature and obeys the Arrhenius law, attributed to the decreasing micellar contour length. of a 40 mM RHTAB/15 mM OHCA solution sharply increases after UV irradiation, mainly because the -isomer could insert into the micelle more easily, and the transition mechanism was studied by UV-vis and H NMR. The multi-responsive self-assembled system may open a new vista for building multi-functional aggregates to adapt to various environmental changes.