Dielectric relaxation studies of ion motions in electrolyte-containing perfluorosulfonate ionomers. 3. Zinc sulfate and calcium chloride systems

Mauritz, Kenneth A.; Hu, Yun

doi:10.1021/ma00191a042

Cited by 24 publications

(17 citation statements)

References 3 publications

(3 reference statements)

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“…The phenomenon of Pt electrode/Nafion™ ionomer interface in HClO 4 was investigated by in situ surface-enhanced FTIR spectroscopy [29] and in situ infrared reflection absorption spectroscopy (IRRAS) [30]. Many studies have been carried out to characterize the behaviour of absorbed water in the membrane such as nuclear magnetic resonance (NMR) [31,32] infrared spectroscopy (IR) [33] differential scanning calorimetry (DSC) [34] and dielectric relaxation [35][36][37]. Recently, the intermolecular interaction energies between a water molecule and four models of pendant chains of perflorosulphonated ionomers were analyzed using molecular orbital calculation [38].…”

Section: Introductionmentioning

confidence: 99%

Intermolecular Interactions Between Methanol/Water Molecules and Nafion™ Membrane: An Infrared Spectroscopy Study

Tsai

Hwang

2007

Fuel Cells

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The intermolecular interactions between methanol/water and Nafion™ membranes have been investigated using IR spectroscopy. The evolution of IR spectra of the Nafion™ membranes, immersed in various concentrations of methanol solution depends strongly on the methanol concentration. The O–H bending vibration modes at 1,636, 1,660 and 1,672 cm–1 associated with the hydrogen bonding of (H3O+…SO3–) as well as (CH3OH2+…SO3–), and at 1,702, 1,717 and 1,711–1,736 cm–1 associated with the hydrogen bonding of (CF2…H–O–CH3), (CF2…H–OH), (CF2…+H3O) and (CF2…H–OSO2–) were observed. The vibration mode of (CF2…H–O) was found to be appearing obviously at 3,821–3,900 cm–1 when the Nafion™ membrane was immersed in the methanol solution with concentration higher than 6 M. On the other hand, the wavenumber of the O–H stretching peak increases with an increase in the methanol concentration. Results of IR spectra revealed that the methanol molecules show better capability to penetrate into the hydrophobic domain of the Nafion™ membrane than water. The intermolecular interaction between the hydrophobic domains of Nafion™ and methanol molecules becomes more observable at a higher methanol concentration.

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Section: Introductionmentioning

confidence: 99%

Intermolecular Interactions Between Methanol/Water Molecules and Nafion™ Membrane: An Infrared Spectroscopy Study

Tsai

Hwang

2007

Fuel Cells

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“…As expected, σ DC increases with temperature in both reference sample and composite. Moreover, the n parameter values of 0.17 tend low compared to those obtained for ionic conductors, 0.5 < n < 1, [82] and they are independent from both temperature and graphene nanoplatelets addition. In contrast, the values of σ DC are affected by GNPs: indeed, at room temperature they increase 4 times with respect to those measured in the reference sample at room temperature, and this effect grows with temperature.…”

Section: Dielectric Responsementioning

confidence: 60%

Elucidation of Conduction Mechanism in Graphene Nanoplatelets (GNPs)/Cement Composite Using Dielectric Spectroscopy

Goracci

Dolado

2020

Materials

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Understanding the mechanisms that govern the conductive properties of multifunctional cement-materials is fundamental for the development of the new applications proposed to enhance the energy efficiency, safety and structural properties of smart buildings and infrastructures. Many fillers have been suggested to increase the electrical conduction in concretes; however, the processes involved are still not entirely known. In the present work, we investigated the effect of graphene nanoplatelets (1 wt% on the electrical properties of cement composites (OPC/GNPs). We found a decrease of the bulk resistivity in the composite associated to the enhancement of the charge transport properties in the sample. Moreover, the study of the dielectric properties suggests that the main contribution to conduction is given by water diffusion through the porous network resulting in ion conductivity. Finally, the results support that the increase of direct current in OPC/GNPs is due to pore refinement induced by graphene nanoplatelets.

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“…As hydration occurs in the polar SO 3 H aggregates, the α relaxation would naturally respond more rapidly to the removal of water molecules by thermal means. Relaxation times, proton hopping pathways and proton conductivity Parameters were extracted from the fit of the H-N equation to the experimental data to quantify and correlating relaxation and d.c. conduction processes in Nafion ® (12)(13)(14)(15)(16)(17). Figure 5 shows changes in the relaxation times for both β and α peaks upon annealing at 140 o C.…”

Section: Resultsmentioning

confidence: 99%

Broadband Dielectric Spectroscopic Studies of Annealed Nafion® Membranes

Mauritz

Hassan

2009

ECS Trans.

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The dynamics of macromolecular motions as coupled to proton migration in annealed Nafion ® membranes was explored using broadband dielectric spectroscopy. These fundamental molecular processes are of interest at temperatures above 100 o C; in particular, spectral changes were investigated in real-time at 140º C. Loss permittivity vs. frequency spectra of both β and α relaxations showed increased relaxation times with annealing and that water de-sorption was mainly responsible for these behaviors. Spectra were analyzed using the Havriliak-Negami equation and relaxation/conductivity parameters were obtained from equation fitting to experimental data to understand the nature and coupling of conduction and relaxations as annealing progressed in the instrument. A parameter N, reflecting the connectedness of charge hopping pathways, indicated tortuous random pathways. As N decreased with increased annealing time, the conductivity network appears to accumulate more charge traps.

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Dielectric relaxation studies of ion motions in electrolyte-containing perfluorosulfonate ionomers. 3. Zinc sulfate and calcium chloride systems

Cited by 24 publications

References 3 publications

Intermolecular Interactions Between Methanol/Water Molecules and Nafion™ Membrane: An Infrared Spectroscopy Study

Intermolecular Interactions Between Methanol/Water Molecules and Nafion™ Membrane: An Infrared Spectroscopy Study

Elucidation of Conduction Mechanism in Graphene Nanoplatelets (GNPs)/Cement Composite Using Dielectric Spectroscopy

Broadband Dielectric Spectroscopic Studies of Annealed Nafion® Membranes

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