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.