The mechanism difference between CO2 and pH stimuli for a dual responsive wormlike micellar system.

To indicate the difference between pH and CO2 stimuli mechanisms, a dual responsive system is constructed with the aid of N-[3-(dimethylamino)propyl]docosanamide (NDPD) and sodium salicylate (NaSal), which is responsive to pH and CO2. The dual responsive system is characterized by rheometry, cryo-TEM and 1H NMR spectroscopy. After bubbling CO2 or adjusting the pH, the rheological properties indicate the formation of wormlike micelles. The cyro-TEM images also confirmed wormlike micelles. The effect of temperature is also clarified. By comparing the rheological properties of the wormlike micelles with pH and CO2 stimuli conditions, combined with cryo-TEM and 1H NMR results, the stimuli mechanisms of pH and CO2 to the dual responsive system are shown. Through this work, we expect to deepen our understanding of the responsiveness of a self-assembled system.