PVdF-HFP + IL(1-butyl-3-methylimidazolium tetrafluoroborate; [BMIM][BF(4)]) polymeric gel membranes containing different amounts of ionic liquid have been synthesized and characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared (FTIR), differential scanning calorimetry, thermogravimetric analysis (TGA), and complex impedance spectroscopic techniques. Incorporation of IL in PVdF-HFP polymer changes different physicochemical properties such as melting temperature (T(m)), thermal stability, structural morphology, amorphicity, and ionic transport. It is shown by FTIR, TGA (also first derivative of TGA, "DTGA") that IL partly complexes with the polymer PVdF-HFP and partly remains dispersed in the matrix. The ionic conductivity of polymeric gel membranes has been found to increase with increasing concentration of IL and attains a maximum value of 1.6 × 10(-2) S·cm(-1) for polymer gel membrane containing 90 wt % IL at room temperature. Interestingly, the values of conductivity of membranes with 80 and 90 wt % of IL were higher than that of pure IL (100 wt %). The polymer chain breathing model has been suggested to explain it. The variation of ionic conductivity with temperature of these gel polymeric membranes follows Arrhenius type thermally activated behavior.

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H nuclear magnetic resonance relaxometry is applied to investigate the translational and rotational dynamics of ionogels composed of an ionic liquid (IL): 1-ethyl-3-methyl-imidazolium-thiocyanate (EMIM-SCN) confined in a nanoporous SiO matrix. The relaxation studies were performed in the frequency range of 4 kHz-40 MHz and the temperature range of 223-248 K for different concentrations of the IL; the ratio (no. of moles of IL/no. of moles of SiO) yields: 1/2, 3/5 and 7/10. A thorough analysis of this large set of experimental data was performed assuming the existence of two fractions of the liquid: a core fraction (near the pore center) and a surface fraction (near the confining walls). It was shown for all concentrations that the confinement does not significantly affect the translational motion near the pore center compared to the dynamics in bulk. The diffusion coefficients in the surface fraction are considerably smaller compared to the core fraction (from one to two orders of magnitude) and the difference becomes larger with increasing temperature. The diffusion coefficients become smaller for higher concentrations - this effect is not large, but visible. Very importantly, it was shown that, despite the interactions with the surface, the diffusion in the surface fraction remains of 3D character. As far as rotational dynamics in the surface fraction is concerned, it slows down compared to the bulk (and the core fraction), but this effect is of the order of factor 2-3.

Polymer electrolytes, (PEO:LiClO4)+x IL (1‐Buty‐3‐methylimidazolium hexafluorophosphate) with varying concentration of IL; x = 0,5,10,15,20 wt % have been prepared by solution cast technique and characterized by X‐Ray diffraction, differential scanning calorimetery, FTIR, conductivity and dielectric relaxation measurements in the frequency range of 100 Hz–5 MHz. Temperature dependence of relaxation frequency and conductivity were found to be typical of thermally activated process both at T > Tm and T < Tm. Composition dependence of conductivity, dielectric relaxation, and degree of crystallinity has also been studied. On addition of IL, the degree of crystallinity after a decrease at 5 wt % IL increases slightly at 10 wt % and then finally decreasing. Variation of conductivity and relaxation frequency with composition could only be partly explained on the basis of variation of degree of crystallinity. An additional feature of ion–ion interaction (contact ion pair formation between IL or salt cations and their associated anions) has been invoked which was supported by FTIR studies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011

Ion-polymer and ion-ion association in polymer electrolyte films of PEO complexed with salt LiClO 4 , ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF 6 ) and (LiClO 4 + BMIMPF 6 ) have been studied by laser Raman spectroscopy. The cations (Li + and/or BMIM + ) of the dopant salt/IL are shown to complex with the ether oxygen of the polymer backbone (i.e. C-O-C bond of PEO). The polymer-cation complexation results in the appearance of an additional peak at ∼1131 cm −1 apart from the C-O-C stretching vibrations of PEO at ∼1062 and 1141 cm −1 . This peak due to polymer-cation complexation is relatively strong for LiClO 4 than BMIMPF 6 , indicating stronger interaction for the former. In the PEO : LiClO 4 and PEO : BMIMPF 6 spectra, Raman peaks at 937 and 747 cm −1 , respectively related to Li + · · · ClO − 4 and BMIM + · · · PF − 6 'contact ion pairs', have also been observed as a result of ion-ion association. In the polymer electrolyte PEO : LiClO 4 + BMIMPF 6 which contained two different anions, viz. ClO − 4 and PF − 6 , an interesting observation of the formation of 'cross contact ion pairs' viz. Li + · · · PF − 6 and BMIM + · · · ClO − 4 is also reported.