By dynamic light scattering (DLS) and transmission electron microscopy (TEM), it is shown that spherical vesicles are formed spontaneously in the mixed systems consisting of sodium dodecyl benzene sulfonate (SDBS) and N′-dodecyl-N,N-dimethylacetamidinium bicarbonate (DAB). These vesicles can be successfully tuned by alkali, but not CO2-switch due to the unsuitable pKa of DAB. In SDBS/DAB system, alkalinity increase can substantially expand the vesicle size in DAB-rich zone, but same effect is indistinguishable in SDBS-rich zone. Only DAB solution can also form vesicles when the solution pH is close to the pKa of DAB.
Practical applications: The vesicles can be spontaneously formed by mixing DAB and SDBS aqueous solution at various concentrations and mole fractions. These vesicles can expand gradually as the solution pH increases. They can be used as pH-response vesicles for application in drug-delivery, size-selective release, biochemical reactions, and so on.
Mixing SDBS and DAB aqueous solution can spontaneously form vesicles at various concentration and mole fraction. The vesicles cannot be tuned by CO2/Ar stimuli. The pH increase by adding NaOH can expand the vesicle size in DAB-rich zone, but the same effect is indistinguishable in SDBS-rich zone.