Role of Solubilized Water in Micelles Formed by Triton X-100 in 1-Butyl-3-methylimidazolium Ionic Liquids

We demonstrate here the aggregation behavior of a nonionic surfactant Triton X-100 in two 1-butyl-3-methylimidazolium ionic liquids (the hydrophilic IL [bmim][BF4] and the hydrophobic IL [bmim][PF6]) by surface tension measurements. The effects of added water on the microstructure of Triton X-100 in ILs micelles are investigated. When small amounts of water are added to Triton X-100 in [bmim][PF6] micelles, the water molecules are first bound to the ethylene oxide (EO) units of Triton X-100 and then form the water pool in the core of the microemulsion. When water molecules are added to the Triton X-100 in [bmim][BF4] micelles, there is no microemulsion formed; these water molecules are first solubilized in [bmim][BF4]. When the solubilization is saturated, the water molecules start to bind to the EO group of Triton X-100; these results are confirmed by UV-vis, FTIR, and H-1 NMR spectra.