Polymeric perfluorinated sulfonic

The polymeric perfluorinated sulfonic acid has been used as a matrix for a system which combines semiconductor CdS crystallites and a Pt hydrogen-evolution catalyst In a photocatalytlc hydrogen generator (73-74). Upon photolysis of the platinized CdS particles In the presence of a sacrificial electron donor, Na.S, the production of hydrogen gas by water reduction was observed. The number of moles of produced with a typical NAFION/(MS system exceeds the moles of CdS present by a factor greater than 100. 

Polymeric resin sulfonic acids including sulfonic acid resins complexed with Lewis acids and perfluorinated polymer resin acids (Nafion-H and Nafion-silica nanocomposites). 

Olah, G. A., Arvanaghi, M., Krishnamurthy, V. V. Heterogeneous catalysis by solid superacids. 17. Polymeric perfluorinated resin sulfonic acid (Nafion-H) catalyzed Fries rearrangement of aryl esters. J. Org. Chem. 1983,48, 3359-3360. 

There are two types of polymeric electrolyte, based on their conduction mechanisms. The first group is the polyelectrolyte in which the polymer itself contains an anionic or cationic group, usually on a side chain. The counter-ions for these groups are typically small, inorganic ions that are mobile within the polymer matrix. Nafion, a perfluorinated sulfonated ionomer made by du Pont, is an example of this type of electrolyte [1]. Nafion has been used as the electrolyte in several amperometric gas sensors. 

The development of polyaryls, in particular polyetherketones (PEEK), as a substitute of perfluorinated polymers was mainly based on cost and stability considerations [1]. Sulfonated polyetherketones has been found to be durable under fuel cell operation conditions over several thousand hours [185]. Victrex Company is the main producer of PEEK polymer and its sulfonation can be performed directly on the polymer backbone or by polymerization of sulfonated monomers [7]. Hoechst-Aventis and Eumatech commercialize sulfonated PEEK (sPEEK) and sulfonated poly(phtalazinone ether ketone) (sPPEK) membranes for fuel cell applications [3]. 

Nafion-H, a polymeric perfluorinated resin sulfonic acid, in refluxing nitrobenzene for 12 h (71%) [38]. 

Nafion-H (144), a perfluorinated resin-sulfonic acid, is an efficient Bronsted-acid catalyst which has two advantages it requires only catalytic amounts since it forms reversible complexes, and it avoids the destruction and separation of the catalyst upon completion of the reaction [94], Thus in the presence of Nafion-H, 1,4-benzoquinone and isoprene give the Diels-Alder adduct in 80% yield at 25 °C, and 1,3-cyclohexadiene reacts with acrolein at 25 °C affording 88 % of cycloadduct after 40 h, while the uncatalyzed reactions give very low yields after boiling for 1 h or at 100 °C for 3.5 h respectively [95], Other examples are given in Table 4.24. In the acid-catalyzed reactions that use highly reactive dienes such as isoprene and 2,3-dimethylbutadiene, polymerization of alkenes usually occurs with Nafion-H, no polymerization was observed. 

Since PTFE was first synthesized more than 50 years ago, fluoropolymers have been produced by radical polymerization and copolymerizaton processes, but without any functional groups, for several reasons. First, the synthesis of functional vinyl compounds suitable for radical polymerization is much more complicated and expensive in comparison with common fluoroolefins. In radical polymerization of one of the simplest possible candidates—perfluorovinyl sulfonic acid (or sulfonyl fluoride—there was not enough reactivity to provide high-molecular-weight polymers or even perfluorinated copolymers with considerable functional comonomer content. Several methods for the synthesis of the other simplest monomer—trifluoroacrylic acid or its esters—were reported,1 but convenient improved synthesis of these compounds as well as radical copolymerization with TFE induced by y-irradiation were not described until 1980.2... 

Surfactants used in the polymerization are water-soluble, halogenated surfactants. They are in particular fluorinated surfactant such as ammonium, substituted ammonium, quarternary ammonium, or alkali metal salts of perfluorinated or partially fluorinated alkyl carboxylates, monoalkyl phosphate esters, alkyl ether or polyether carboxylates, alkyl sulfonates, and alkyl sulfates. 

Figure 5. Cluster-network model for Nafion perfluorinated membranes. The polymeric ions and absorbed electrolyte phase separate from the fluorocarbon backbone into approximately spherical clusters connected by short, narrow channels. The polymeric charges are most likely embedded in the solution near the interface between the electrolyte and fluorocarbon backbone. This configuration minimizes both the hydrophobic interaction of water with the backbone and the electrostatic repulsion of proximate sulfonate groups. The dimensions shown were deduced from experiments. The shaded areas around the interface and inside a channel are the double layer regions from which the hydroxyl ions are excluded electrostatically.

Nafion is a perfluorinated ion-exchange polymer. It is an ionomer with a chemically resistant polymeric backbone and highly acidic sulfonic acid group... 

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