Perfluorocarbons chemical reactivity

The effect of the polymer backbone on the intrinsic chemical reactivity of metal complexes has been studied in aqueous solution and in Nafion (perfluorocarbon sulfonic acid) film 44). Using a model catalyst-substrate system, the independent kinetic effects of reaction site homogeneity, substrate diffusion into the polymer film, and changes on activation parameters have been addressed. The ligand substitution reaction (6), was chosen for this purpose (Py = pyridine and its derivatives). 

In addition to their separation properties, perfluorocarbons have advantages as solvents they are chemically unreactive, non-flammable and have a low toxicity. But their low reactivity leads to long lifetimes and as these solvents are still volatile (see boiling points in Table 7.1), there is a high chance that atmospheric contamination will occur. 

Although perfluorocarbon sulfonic acid groups are very stable chemically as well as thermally, perfluorocarbon sulfonyl halide, especially sulfonyl chloride groups, are quite reactive. For example, sulfonyl chloride groups react with oxidants, reductants, various amines, phenol compounds, iodine compounds, etc. and give carboxylic acid, sulfinic acid, sulfonic acid amide, -CF2I and so forth. Some examples of how this feature can be used to generate various kinds of membranes will next be described... 

Fluorine substitution on carbon confers particular reactivity because of its particular properties Fluorine as the most electronegative element forms very strong CF bonds which are sized to "cover" perfluorocarbons tightly. Polytetrafluoroethylene (Teflon) is one practical example illustrating the exceptional chemical and thermal stability of saturated perfluorocarbons in a sharp contrast to explosive tetrafluoroethylene or to fluoroacetylenes. 

Mechanism for Chemical Surface Modification. Since PTFE films having no significant absorption at 193 nm were not excited upon the irradiation with an ArF laser, hydrazine is only photodissociated by the irradiation. Photolysis of hydrazine upon the ArF irradiation has been investigated in detail by Hawkins (31) and Lindberg (32). The irradiation of hydrazine in a gas phase produces reactive species such as N2H3, NH2, and H radicals and NH nitrene in high efficiency. By assuming that these species attack the PTFE surface, we studied a preliminary reaction path for these reactive species and perfluorocarbons, that is, which species can react with perfluoroalkyl molecules. 

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