Interaction of ionic liquid with water with variation of water content in 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF_6])/TX-100/water ternary microemulsions monitored by solvent and rotational relaxation of coumarin 153 and coumarin

摘要

The interaction of water with room temperature ionic liquid (RTIL) [bmim][PF_6] has been studied in [bmim][PF_6]/TX-100/water ternary microemulsions by solvent and rotational relaxation of coumarin 153 (C-153) and coumarin 490 (C-490). The rotational relaxation and average solvation time of C-153 and C-490 gradually decrease with increase in water content of the microemulsions. The gradual increase in the size of the microemulsion with increase in w_0 (w_0=[water]/ [surfactant]) is evident from dynamic light scattering measurements. Consequently the mobility of the water molecules also increases. In comparison to pure water the retardation of solvation time in the RTIL containing ternary microemulsions is very less. The authors have also reported the solvation time of C-490 in neat [bmim][PF_6]. The solvation time of C-490 in neat [bmim][PF_6] is bimodal with time constants of 400 ps and 1.10 ns.