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

Abstract

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.