Surfactant Aggregates in Ionic Liquids and Reactivity in Media

In this paper the association of different families of amphiphilic compounds in room temperature ionic liquids in micelles, vesicles and reverse microemulsions was demonstrated. First the formation of nonionic polyoxyethylene-type surfactant micelles in the ionic liquid 1-butyl-3-methyl-imidazolium tetrafluoroborate is clearly evidenced using tensiometry and dynamic light scattering measurements. Critical micellar concentrations, object sizes and aggregation numbers are given and compared to aqueous and formamide systems. Then, vesicular aggregation of glycerophospholipid DPPC in two ionic liquids bmimBF(4) and emimNTf(2) was evidenced. Lastly, the phase diagram and microstructure of the ternary system ionic liquid (benzylpyridinium bis(trifluoromethanesulfonyl) imide)/nonionic surfactant (octylphenol ethoxylate)/toluene were studied. Phase stability and small-angle neutron scattering data show the formation of ionic liquid-in-oil microemulsion droplets. These reverse microemulsions were used as nanoreactors to perform a Matsuda-Heck reaction. The reaction yields obtained were greater in microemulsions (67%) than in bulk IL (33%) highlighting a strong effect of confinement. The reactivity in these confined media led to promising results.