Reversible multi-induced transformation between wormlike micelles and gels

A novel CO 2 responsive self-assembled surfactants system was prepared using N - [3 - (dimethylamino) propyl] docosanamide (NDPD) and sodium salicylate (NaSal). Rheological measurements were performed to study the phase behaviors of NDPD/NaSal system. It was found that gels and wormlike micelles can be formed in the NDPD/NaSal system. The phase behaviors were found to be influenced by changing temperature or by involving different anions. Through increasing the temperature, gels can transform to wormlike micelles . When HCl and CO 2 were used to adjust pH, NDPD/NaSal system performed decidedly different rheological behaviors at the same pH. By theoretical calculation, it was found that the binding energy between NDPD and Cl − is larger than that of NDPD and HCO 3 − , indicating a stronger shielding ability of Cl − ions. Due to the weakened electrostatic repulsion interactions, the internal structure of NDPD/NaSal switchable system wrapped more tightly through adding HCl compared with adding CO 2 .