Design and functionalization of magnetic ionic liquids surfactants (MILSs) containing alkyltrimethylammonium fragment

A series of magnetic ionic liquids surfactants (MILSs) containing alkyltrimethylammonium fragment {dodecyltrimethylammonium bromotrichloroferrate (III) ([DTA][FeCl 3 Br]), tetradecyltrimethylammonium bromotrichloroferrate (III) ([TTA][FeCl 3 Br]), cethyltrimethylammonium bromotrichloroferrate (III) ([CTA][FeCl 3 Br]), and stearyltrimethylammonium bromotrichloroferrate (III) ([STA][FeCl 3 Br])} were synthesized and characterized by FT-IR, Raman and MS (ESI) spectra. The physical properties including thermal stability, density and magnetic susceptibility were determined, which revealed that the MILSs had good thermal stability ( T d  > 210 °C) and considerable magnetic susceptibility ( x g  > 3.2 × 10 −5  emu·g −1 ). The critical micelle concentration (CMC) values of MILSs aqueous solutions based both on electrical conductivity method and surface tensiometry demonstrated that MILSs had better surface active than the corresponding nonmagnetic parent surfactants {dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), cethyltrimethylammonium bromide (CTAB) and stearyltrimethylammonium bromide (STAB)}. Moreover, the surface tensiometry in a magnetic field revealed that the MILSs showed a magnetically induced reduction in surface tension. With surface active and magneto-responsivity bi-functional properties, allow these MILSs pretend to be manipulated noninvasively and reversibly by an applied external magnetic field in further potential applications such as colloid and surface chemistry.