title: Microemulsions with surfactant TX100, cyclohexane, and an ionic liquid investigated by conductance, DLS, FTIR measurements, and study of solvent and rotational relaxation within this microemulsion.
abstract: Room-temperature ionic liquids (RTILs), N,N,N-trimethyl-N-propyl ammonium bis(trifluoromethanesulfonyl) imide ([N(3111)][Tf(2)N]), were substituted for polar water and formed nonaqueous microemulsions with cyclohexane by the aid of nonionic surfactant TX-100. The phase behavior of the ternary system was investigated, and microregions of [N(3111)][Tf(2)N]-in-cyclohexane (IL/O), bicontinuous, and cyclohexane-in-[N(3111)][Tf(2)N] (O/IL) were identified by traditional electrical conductivity measurements. Dynamic light scattering (DLS) revealed the formation of the IL microemulsions. The FTIR study of O-H stretching band of TX100 also supports this finding. The dynamics of solvent and rotational relaxation have been investigated in [N(3111)][Tf(2)N]/TX100/cyclohexane microemulsions using steady-state and time-resolved fluorescence spectroscopy as a tool and coumarin 480 (C-480) as a fluorescence probe. The size of the microemulsions increases with gradual addition of [N(3111)][Tf(2)N], which revealed from DLS measurement. This leads to the faster collective motions of cation and anions of [N(3111)][Tf(2)N], which contributes to faster solvent relaxation in microemulsions.
authors.affiliation: Department of Chemistry Indian Institute of Technology, Kharagpur 721302, WB, India.
authors.forename: Rajib
authors.initials: R
authors.lastname: Pramanik
authors.forename: Souravi
authors.initials: S
authors.lastname: Sarkar
authors.forename: Chiranjib
authors.initials: C
authors.lastname: Ghatak
authors.forename: Vishal Govind
authors.initials: VG
authors.lastname: Rao
authors.forename: Palash
authors.initials: P
authors.lastname: Setua
authors.forename: Nilmoni
authors.initials: N
authors.lastname: Sarkar