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

Abstract

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.