Amphiphile regulated ionic-liquid-based aqueous biphasic systems with tunable LCST and extraction behavior

Ionic liquid (IL)/H 2 O mixtures with tunable lower critical solution temperature (LCST) behavior exhibit tantalizing prospect in the field of liquid-liquid phase separation and purification. Herein, different types of amphiphiles were evaluated for the facile regulation of IL ([P 4444 ][DMBS]) based aqueous biphasic systems (ABSs). Interestingly, the addition of zwitterionic 3-(1-dodecyl-3-imidazolio) propanesulfonate (DIPS) remarkably increases the phase separation temperature of IL aqueous solution, while the addition of anionic sodium dodecyl benzene sulfonate (SDBS) and dodecyl-benzenesulphonic acid (DBSA) results in decreasing of the phase separation temperature. The tunable phase separation temperature ranges from 10 to 90 °C, which almost cover the full usable temperature range of ABSs. The regulation mechanism of amphiphile additives on the LCST behavior of IL/H 2 O mixtures was investigated through isothermal titration calorimetry , 1 H NMR spectroscopy and molecular dynamics simulations . Briefly, the addition of zwitterionic DIPS increased LCST through electrostatic shielding effect, while the addition of anionic SDBS and DBSA decreased LCST through ion exchange effect. As a proof of concept, the amphiphile regulated ABSs were demonstrated to selectively separate aliphatic and aromatic amino acids .