Ammonium Form of Nafion Plasticized by Dimethyl Sulfoxide

Abstract

The work addresses the properties of electro-transport in highly ion-conductive polymer electrolytes based on Nafion-115 membranes in the NH 4 + ionic form plasticized with dimethyl sulfoxide (DMSO). The ionic conductivity and the activation energy of the conductivity were found to exhibit three types of behavior as a function of the plasticizer. The first region (when the ratio of moles of DMSO molecules per mole of NH 4 + (n) < 6) is characterized by low conductivity values (10 −7 -10 −4 S cm −1 ) and high energy barriers (0.76 and 0.43 eV for n = 0 and 2.6, respectively). In the second region (n = 6-12), the electrolyte has a high conductivity and a low activation energy of conductivity (∼0.1 eV). With an increase in the DMSO content, the conductivity appreciably increases and reaches ∼ 0.4 mScm −1 . In the third region (n ≥ 12) the transport parameters are comparable to those of the second region, but the conductivity is practically independent of the DMSO content. The observed behavior was explained on the basis of the results obtained with the help of IR spectroscopy, differential scanning calorimetry, small-angle X-ray scattering and quantum-chemical modeling.

Li-Nafion Membrane Plasticised with Ethylene Carbonate/Sulfolane: Influence of Mixing Temperature on the Physicochemical Properties

“…Based on changes in T g and diffraction profiles of swollen membranes, it can be assumed that the penetration of the solvent into the amorphous regions of the polymer results in a new amorphous structure that includes not only macromolecules but also low-molecular-weight solvent. Unlike water, molecules of some polar organic solvents can interact with PFSA chains and penetrate amorphous regions to weaken interchain interactions [ 4 , 45 , 50 ]. Moreover, it is known that saturation with water does not cause any noticeable changes in the Nafion diffraction profile [ 46 ].…”

“…The widespread applications of this ionomer material are due to its excellent transport properties, high thermal and chemical stability, combined with stable mechanical behaviour. Ion exchange reactions can be used to convert PFSA ionomers from their original acid form to a salt form using various cations without loss of strength or thermal and chemical stability [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. These properties allow PFSA salts to be used as polymer electrolytes with unipolar cation conductivity.…”

“…Similar to the initial protonated form, the lithiated Nafion (Li-Nafion) membrane is poorly conductive in its dry state. However, upon saturation with dipolar aprotic solvents, a polymer electrolyte offering good transport properties can be obtained [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. The introduction of solvent molecules enhances nanoscale phase separation.…”

Structural Characterization and Physicochemical Properties of Functionally Porous Proton-Exchange Membrane Based on PVDF-SPA Graft Copolymers

“…Numerous studies and review papers have been devoted to the study of PEM [ 1 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ] and suggest that the characteristics of the PEM has a significant effect on the performance and durability of the PEMFCs. Among all commercial samples for the PEMFC applications, the most used membranes are perfluorosulfonic acid (PFSA) due to its stability, long-term performance, mechanical strength, and low conduction resistance [ 13 , 14 ].…”