Adsorption and aggregation behavior of surface active trisiloxane room-temperature ionic liquids

Three novel surface active room-temperature ionic liquids (RT-ILs), Si(3)N-CA(n)(n = 1, 2, 3), were synthesized, in which trisiloxanes were introduced as hydrophobic group to reduce the ionic liquids’ melting points. Their surface activity and aggregation behavior in aqueous solution were systematically investigated through measurement of surface tension, conductivity, dynamic light scattering (DLS), transmission electron microscopy (TEM), and cyro-transmission electron microscopy (Cyro-TEM). The surface tension of the aqueous trisiloxane RT-ILs solutions measured at the critical aggregate concentration (CAC) were observed to be about 20 mN m−1, much lower than those of traditional N-alkyl ionic liquids. With a combination of DLS data and TEM measurements, formations of multilamellar vesicles in trisiloxane RT-ILs solutions appear to occur at a concentration above the CAC.