Oligomeric surfactants display the novel properties of low surface activity, low critical micellar concentration and enhanced viscosity, but no CO2 switchable oligomeric surfactants have been developed so far. The introduction of CO2 can convert tertiary amine reversibly to quaternary ammonium salt, which causes switchable surface activity. In this study, epoxidized soybean oil was selected as a raw material to synthesize a CO2-responsive oligomeric surfactant. After addition and removal of CO2, the conductivity analyzing proves that the oligomeric surfactant had a good response to CO2 stimulation. The viscosity of the oligomeric surfactant solution increased obviously after sparging CO2, but returned to its initial low viscosity in the absence of CO2. This work is expected to open a new window for the study of bio-based CO2-stimulated oligomeric surfactants.
Keywords: CO2 switching; emulsion; oligomeric surfactant; soybean oil; surface activity; viscosity.