Colloids with reversible stability switched by tris[2-(dimethylamino)ethyl]amine

The addition of salt can irreversibly disrupt the stability of both emulsions and polymer latex. The reversible conversion of amines into organic ammonium salts can be induced by CO₂ stimulation, thereby enabling the switching of colloids. The switchable amine, tris[2-(dimethylamino)ethyl]amine (Me₆TRAN), was selected for the study. The electrical conductivity of an aqueous solution of Me₆TRAN is modulated by the introduction and removal of CO₂. The critical micelle concentration of sodium dodecyl benzene sulfonate (SDBS) was observed to decrease from 1.0 × 10⁻³ to 5.0 × 10⁻⁴ M upon the introduction of Me₆TRAN, as confirmed by surface tension measurements conducted under CO₂. The emulsion of crude oil, which comprised of SDBS and Me₆TRAN, underwent reversible destruction and restoration upon exposure to CO₂ and N₂. The PMMA latex exhibited a clear phase separation subsequent to CO₂ sparging, but attained homogeneity upon N₂ sparging. This study is anticipated to introduce a novel avenue for emulsion or polymer latex that can undergo demulsification and emulsification through CO₂ stimulation.