Showing papers on "Nafion published in 1981"
TL;DR: In this article, the morphology of the ionomer resin from which Nafion perfluorinated membrane products are made was studied with wide-angle and small-angle x-ray diffraction.
Abstract: The morphology of the ionomer resin from which Nafion perfluorinated membrane products are made was studied with wide-angle and small-angle x-ray diffraction. A reflection observed in the small-angle x-ray scan from hydrolyzed polymer is attributed to ionic clustering. The effects of equiv wt, cation form, temperature, water content, and tensile drawing on this reflection were studied and are discussed.
1,284 citations
TL;DR: In this article, self-diffusion coefficients for sodium ion, cesium ion, and water have been measured for Nafion® 120 perfluorosulfonate ion exchange membranes.
Abstract: Membrane self‐diffusion coefficients for sodium ion, cesium ion, and water have been measured for Nafion® 120 perfluorosulfonate ion exchange membranes. Values have been determined as a function of temperature, and as a function of membrane water content by studying samples in heteroionic forms. The diffusional properties of this polymer are found to differ from those of conventional polystyrenesulfonates in several respects, and the free volume theory which describes ionic diffusion in the latter is inappropriate to treat Nafion. Results indicate that cations may exist in two distinct regions in the polymer; the proportion of total cations in each region may depend on the ions size and charge density. A structural model of Nafion, which correlates the membrane's spectroscopic and diffusional properties, is proposed to explain the results.
511 citations
TL;DR: RubRubinstein and Allen J. Bard as discussed by the authors, 1981, 103 (17), 5007-5013, 10.1021/ja00407a006, 11.13.2009
Abstract: Journal of the American Chemical Society is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Polymer films on electrodes. 5. Electrochemistry and chemiluminescence at Nafion-coated electrodes Israel Rubinstein, and Allen J. Bard J. Am. Chem. Soc., 1981, 103 (17), 5007-5013• DOI: 10.1021/ja00407a006 • Publication Date (Web): 01 May 2002 Downloaded from http://pubs.acs.org on February 13, 2009
283 citations
63 citations
TL;DR: In this paper, the authors measured the proton magnetic resonance relaxation times and heat capacity of water in perfluoroethylene sulfonic acid (Nafion), chlorosulfonated polyethylene (SPE), and sulfonate polysulfone (SPS) as a function of temperature.
Abstract: The proton magnetic resonance relaxation times and heat capacity of water in perfluoroethylene sulfonic acid (Nafion), chlorosulfonated polyethylene (SPE), and sulfonated polysulfone (SPS) were measured as a function of temperature. Only the relaxation data for water present in Nafion conformed to the BPP model. The data indicate that the presence of fine pores, ∼12 A in diameter, causes water–surface interactions to play a significant role. For materials with the same pore size, a difference in spin-lattice relaxation time T1 may be correlated to the Flory–Huggins parameter χ calculated for the interaction of water with the neutral portion of the polymer backbone. Only a part of the water present in Nafion and SPE undergoes freezing, while no transition was observed for water in SPS for temperatures down to −60°C. For Nafion and SPE, the heat of fusion ΔHf calculated from combined FID data and the DSC study was ⋍20 cal/g.
57 citations
TL;DR: Henning et al. as discussed by the authors used tetrathiafulvalenium in a polyelectrolyte (Nafion) matrix to produce polymers with poly(n) films on electrodes.
Abstract: Journal of the American Chemical Society is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Polymer films on electrodes. 6. Bioconductive polymers produced by incorporation of tetrathiafulvalenium in a polyelectrolyte (Nafion) matrix Timothy P. Henning, Henry S. White, and Allen J. Bard J. Am. Chem. Soc., 1981, 103 (13), 3937-3938• DOI: 10.1021/ja00403a061 • Publication Date (Web): 01 May 2002 Downloaded from http://pubs.acs.org on February 13, 2009
56 citations
40 citations
TL;DR: Colloidal silver particles were produced and characterized in the perfluorosulfonate membrane, Nafion 120, and analysis of the rate of this reaction indicates that only a small fraction of the particles' surface is accessible to the reactants.
29 citations
26 citations
TL;DR: In this article, the swelling properties of Nafion and six radiation-grafted cation exchange membranes in various solvents were investigated and it was found that the swelling of the membranes was strongly related to the type of ion exchange group and was not influenced by the perfluorinated nature of the polymer.
20 citations
TL;DR: In this paper, the effects of β and γ radiation on the Nafion perfluorinated ion-exchange polymer have been examined and the radiolysis products have been identified.
Abstract: The effects of β and γ radiation on the Nafion perfluorinated ion-exchange polymer have been examined and the radiolysis products have been identified. The polymer degrades by simple chain scission, and the rate of degradation is not affected by the state of polymer hydration of the nature of the ion which occupies an exchange site.
01 Jan 1981
TL;DR: In this paper, a transmission electron micrograph of Nafion stained with silver ions is shown, where the polar groups self-associate to form hydrophilic clusters in a sea of nonpolar material.
Abstract: Ionomers are two-phase materials which show considerable promise as ion-selective membranes. Nafion,† in particular, is being used on a limited commercial basis in chloralkali separation processes. Its chemical structure, shown in Figure 1, is typical of ionomers. Pendant side chains, each containing an ionizable group, are essentially spaced uniformly along a linear chain composed of relatively nonpolar groups. The number of nonpolar units is far greater than the number of polar-ionizable groups. This leads to the particular two-phase structure. Polar groups self-associate to form hydrophilic clusters in a sea of nonpolar material. In general, ionomeric structure has been studied by X-ray diffraction, dielectric and mechanical spectroscopies, and by electron microscopy.(1–3) The polar clusters of Nafion have also been investigated by infrared(4) and NMR(5) spectroscopies. Figure 2 shows a transmission electron micrograph of Nafion stained with silver ions. The clusters appear as dark dots.