Unique phase behavior of a room-temperature ionic liquid, trimethylpropylammonium bis(fluorosulfonyl)amide: surface melting and its crystallization.

The phase behavior of a representative ammonium-based ionic liquid, trimethylpropylammonium bis(fluorosulfonyl)amide ([N1113][FSA]), was investigated using a laboratory-made differential scanning calorimeter (DSC). The apparatus possesses extremely high sensitivities with stability of ±2 nW in thermal flux and ±1 mK in temperature and a very slow scanning rate of 0.001 mK s-1 in the slowest scanning speed.

Ultraslow dynamics at crystallization of a room-temperature ionic liquid, 1-butyl-3-methylimidazolium bromide.

We studied the crystallization process of 1-butyl-3-methylimidazolium bromide ([C(4)mim]Br) using measurements of supersensitive scanning calorimetry, free induction decay (FID) signals of (1)H NMR, and direct observation. These three methods provided consistent, complementary results, which showed extremely slow dynamics at crystallization. This sample does not crystallize during the cooling process, loses mobility, and changes to a coagulated state, which is not the thermodynamic glass state.

Phase behaviors of room temperature ionic liquid linked with cation conformational changes: 1-butyl-3-methylimidazolium hexafluorophosphate.

We have investigated phase-transition behaviors of a typical room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim]PF(6)), using calorimetric and Raman spectroscopic techniques. Although there was some confusion on its phase behaviors in previous reports, our measurements with a laboratory-made calorimeter at a slow scanning rate (5 mK/s) have definitely revealed that [C(4)mim]PF(6) has three crystalline phases. From the Raman spectroscopic study, the conformations of the butyl group for these crystalline phases are assigned to gauche-trans, trans-trans, and gauche'-trans conformations in lower-energy order.

Thermodynamic and FTIR studies of supercooled water confined to exterior and interior of mesoporous MCM-41.

The thermal properties of water confined to both exterior and interior of cylindrical mesoporous MCM-41 (pore diameter d = 1.8-3.6 nm) were analysed by differential scanning calorimetry and FTIR spectroscopy.

Melting and freezing behaviors of prototype ionic liquids, 1-butyl-3-methylimidazolium bromide and its chloride, studied by using a nano-Watt differential scanning calorimeter.

1-Butyl-3-methylimidazolium bromide ([bmim]Br) and its chloride ([bmim]Cl) are representative prototypes of ionic liquids. We investigated the melting and freezing behaviors of [bmim]Br and [bmim]Cl by using a homemade differential scanning calorimeter (DSC) with nano-Watt stability and sensitivity. The measurements were carried out at heating and cooling rates slow enough to mimic quasi-static processes.