Designing the head group of CO2-triggered switchable surfactants†
Abstract
The synthesis of a small library of nitrogen-based CO2-switchable cationic surfactants with different head groups is described. These switchable surfactants can be switched on by addition of CO2 and switched off by the removal of CO2. The structure of the switchable head group affects the surfactant's basicity, solubility, heat of protonation, rate and extent of switching, and ability to reversibly stabilize and demulsify oil–water emulsions.