From nonionic to zwitterionic: Novel CO2-responsive zwitterionic wormlike micelles based on zwitterionic surfactant and bola-type asymmetric diamine

CO 2 enhanced oil recovery (CO 2 -EOR) is one of the CO 2 utilization methods which can also geo-sequestrate greenhouse gases. Due to the weak adsorption on rock surface and excellent viscoelasticity performance, CO 2 -responsive zwitterionic wormlike micelles (WLMs) has been recognized as a promising method to control CO 2 channeling. A novel CO 2 responsive zwitterionic WLMs was developed by blending N -octadecyl- N , N -dimethyl-3-ammonio-2-hydroxy-1-propane-sulfonate (OHSB), N , N , 2 , 2 -tetramethyl-1,3-propanediamine (TADPA) and sodium salicylate (NaSal). The responsive behaviors induced by varying agents (CO 2 and HCl) are systematically studied by rheology tests and cryo-TEM measurements. The molecular structures of products are confirmed by 1 H and 13 C NMR. Moreover, the responsive mechanism is discussed in detail. The OHSB/NaSal/TADPA system shows morphological transformations between spherical micelles (a good flowing capacity) and WLMs (conducive to plugging) before and after purging CO 2 . The viscoelasticity and molecular structure of the system with CO 2 bubbling is different from that with HCl titration, because TADPA molecules can react with CO 2 to form a novel zwitterionic product: NH + (CH 3 ) 2 -CH 2 -C(CH 3 ) 2 -CH 2 -NHCO 2 − (TAH + DPACO 2 − , 78.95 %–83.52 %). This work provides a new strategy for the design of CO 2 -responsive zwitterionic WLMs and their applications in CO 2 utilization schemes, including clean fracturing, mobility control, and CO 2 foam flooding, etc.