CO2 regulates phase transition of sodium oleate and 3-(diethylamino)-propylamine in aqueous solution
We reported that the phase conversion of the micelles in aqueous solution prepared by sodium oleate (NaOA) and 3-(diethylamino)-propylamine (DEAPA) in the presence of carbon dioxide. This micellar structure is very sensitive to CO2 and the pH value of the solution is continuously reduced with the continuous introduction of carbon dioxide. When pH > 10.2, the mixed solution of NaOA and DEAPA is mainly in the form of spherical micelles; when the 10.2 > pH > 9.6, the mixed solution mainly in the worm-like micelles (WLM), where the solution has a significant viscosity change; when the 9.6 > pH > 9.1, the NaOA and DEAPA mixed solution becomes the aqueous two-phase system (ATPS), which is composed of two layers, the upper layer is the vesicle structure and the lower layer is the WLM structure; when the pH between 9.1 > pH > 9.0, NaOA and DEAPA mixed solution form vesicles, thus realizing the regulation of CO2 on the micellar structure transition of NaOA and DEAPA mixed solution. Such these microstructures transition could be confirmed by Rheology measurement, DLS and Cryo-TEM.