Surface and foaming properties of an anionic CO2-switchable tail surfactant

Abstract CO2-switchable materials in general and CO2-switchable surfactants in particular are of great interest in environmental research. There is a great potential to make processes more environmentally friendly by enhancing reusability and circularity and thus reducing material costs and energy consumption by replacing common non-switchable surfactants with their switchable counterparts. Inspired by this, the present work deals with the surface and foaming properties of aqueous solutions of the novel anionic CO2-switchable tail surfactant sodium 4-(methyl(octyl)amino)butane-1-sulfonate. In the presence of N2, the unprotonated surfactant is able to stabilize foams. By switching, i.e. by protonating the CO2-responsive trialkyl amine group in the surfactants hydrocarbon chain, the amphiphilic nature of the surfactant is reduced which is indicated by an increase of the plateau surface tension and a higher CMC compared to the non-protonated surfactant. Furthermore, the ability of the protonated surfactant to stabilize foams is reduced.