Reorientational dynamics of glycerol derived from temperature‐dependent multi‐nuclear magnetic resonance relaxation data

Friedrich, Anke; Dölle, Andreas; Zeidler, Manfred

doi:10.1002/mrc.1254

Cited by 14 publications

(11 citation statements)

References 24 publications

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“…As a result, the curve of T 1 vs. temperature in a phase takes on a negative slope at lower temperature and a positive slope at higher temperature, with the minimum value at ot c = 0.62, as demonstrated in the case of glycerin. 28,30,31 For easy comparison with the data of the RTILs, our The cooling and heating rates were 1 mK s À1 . No peak was found in the cooling process.…”

Section: Resultsmentioning

confidence: 99%

NMR study on relationships between reorientational dynamics and phase behaviour of room-temperature ionic liquids: 1-alkyl-3-methylimidazolium cations

Imanari

Uchida

Miyano

et al. 2010

Phys. Chem. Chem. Phys.

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We measured longitudinal and transverse relaxation times (T(1) and T(2)) for (1)H, (13)C-T(1) and (13)C spectra for room-temperature ionic liquids of 1-alkyl-3-methylimidazolium bromide [C(n)mim]Br (n = 2, 3, 4) as a function of temperature. Their values and spectra reveal close relationships between their unique phase behaviours and the dynamics of carbons constituting the cations. Carbons in these cations are classified into groups according to their dynamics, namely imidazolium carbons, an N-methyl carbon, a terminal methyl carbon of the alkyl group and others of the alkyl group. The temperature dependences of T(1) values for these groups differ greatly, resulting in a variation in the characteristic thermal behaviours of the salts. Values of (1)H-T(1) and (13)C-T(1) suggest that some carbons continue to move even in the crystalline and/or solid states. Using (13)C-T(1) data, we also estimated the temperature dependences of the correlation times for the segmental motions of carbons in the liquid states.

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Section: Resultsmentioning

confidence: 99%

NMR study on relationships between reorientational dynamics and phase behaviour of room-temperature ionic liquids: 1-alkyl-3-methylimidazolium cations

Imanari

Uchida

Miyano

et al. 2010

Phys. Chem. Chem. Phys.

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“…distributions of correlation times). To account for such deviations the spectral density suggested by Cole and Davidson (CD) [41][42][43] has been frequently used in place of eqn (3)…”

Section: Evaluation Of Correlation Times From Spin-lattice Relaxation...mentioning

confidence: 99%

Activation of transport and local dynamics in polysiloxane-based salt-in-polymer electrolytes: a multinuclear NMR study

Kunze

Karatas

Wiemhöfer

et al. 2010

Phys. Chem. Chem. Phys.

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We have investigated a new improved lithium ion conducting salt-in-polymer electrolyte system consisting of a polysiloxane backbone with oligoether side chains and added LiCF(3)SO(3) (LiTf), which has a conductivity at 30 degrees C of up to 1.3 x 10(-4) S cm(-1) and up to 6.9 x 10(-5) S cm(-1) after cross-linking, which is employed to enhance mechanical stability. The mechanisms governing local dynamics and mass transport have been studied on the basis of temperature dependent spin-lattice relaxation time and pulsed field gradient diffusion measurements for (7)Li, (19)F and (1)H, respectively. The correlation times characterizing the local ion dynamics reflect the complexation of the cations by the polyether side chains of the polymer and show the anion as the more mobile species. In contrast, (7)Li and (19)F diffusion coefficients and their activation energies are rather similar, suggesting the formation of ion pairs with similar activation barriers for cation and/or anion long-range transport. In general, the activation energies describing local reorientation are significantly smaller than those characterizing long range diffusion, suggesting that the long-range transport of both cations and anions is a much more complex process than a simple succession of free ion jumps, and involves (1) the coupling of conformational side-chain reorientations to the cation movement, and (2) the correlated diffusion of cations and anions within dimers or clusters. An important practical conclusion from our results is that the relatively high ionic conductivity in polysiloxane-based polymer electrolytes could even be increased if salt dissociation could be enhanced further.

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“…distributions of correlation times). To account for such deviations the spectral density suggested by Cole and Davidson (CD) [54][55][56] has been frequently used in place of Eq. (5)…”

Section: Information About Local Motions From Spin-lattice Relaxationmentioning

confidence: 99%

Transport Mechanisms of Ions in Graft-Copolymer Based Salt-in-Polymer Electrolytes

Kunze

Schulz

Wiemhöfer

et al. 2010

Zeitschrift Für Physikalische Chemie

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Polymer Electrolyte / Nuclear Magnetic Resonance / Spin Relaxation / Pulsed Field Gradient NMR / ConductivitySalt-in-polymer electrolytes based on graft copolymers with oligoether side chains and added LiCF 3 SO 3 (LiTf) are investigated concerning the transport and dynamics of the ionic species with respect to applications as Li ion conductors. Polymer architectures are based on polysiloxane or polyphosphazene backbones with one or two side chains per monomer, respectively. NMR methods provide information about molecular dynamics on different length scales: The mechanisms governing local dynamics and long range mass transport are studied on the basis of temperature dependent spin-lattice relaxation rates and pulsed field gradient diffusion measurements for 7 Li, 19 F and 1 H, respectively. The correlation times characterizing local ion dynamics reflect the complexation of the cations by the oligoether side chains of the polymer.7 Li and 19 F diffusion coefficients and their activation energies are rather similar, suggesting the formation of ion pairs and clusters with similar activation barriers for cation and/or anion long-range transport. Activation energies of local reorientations are generally significantly smaller than activation energies of long range diffusion. Long range transport is affected by (1) the coupling of conformational side chain reorientations to the cation movement, and (2) the correlated diffusion of cations and anions within ion pairs. Ion pairs and their dissociation play a major role in controlling the resulting conductivity of the material. Guidelines for material optimization in terms of a maximized conductivity can thus be derived by identifying a compromise between high ionic mobility and good Li complexation by the coordinating side chains.

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Reorientational dynamics of glycerol derived from temperature‐dependent multi‐nuclear magnetic resonance relaxation data

Cited by 14 publications

References 24 publications

NMR study on relationships between reorientational dynamics and phase behaviour of room-temperature ionic liquids: 1-alkyl-3-methylimidazolium cations

NMR study on relationships between reorientational dynamics and phase behaviour of room-temperature ionic liquids: 1-alkyl-3-methylimidazolium cations

Activation of transport and local dynamics in polysiloxane-based salt-in-polymer electrolytes: a multinuclear NMR study

Transport Mechanisms of Ions in Graft-Copolymer Based Salt-in-Polymer Electrolytes

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