Wettability fluorination

Lithium fluoride is an essential component of the fluorine cell electrolyte 1% LiF in the KF 2HF electrolyte improves the wettability of the carbon anodes and lowers the tendency of the cells to depolarize (18). Thermoluminescent radiation dosimeters used in personnel and environmental monitoring and in radiation therapy contain lithium fluoride powder, extmded ribbons, or rods (19). 

Today it is claimed that the surface fluorination of polymers using F2 gas mixtures enhances a wide range of properties, e.g., low permeability to nonpolar liquids4 improved permselectivity,5-6 excellent wettability and adhesion,7 low friction coefficient (especially for elastomers),8 and chemical inertness.9 Obviously, these properties depend on the chemical composition ofthe fluorinated layer, which in turn is determined by the chemical structure ofthe base polymer, the composition of the F2 gas mixture, and the fluorination parameters. 

It is well known that addition of PP fibers to concrete increases water absorption. It is, however, interesting to note that with fluorinated fibers, the water absorption is very similar to unfilled concrete, suggesting an improvement in wettability and chemical adhesion between fiber and matrix. 

In equation 5, C is amorphous carbon and CF2 changes to many perfluorocarbons, such as CF4, C2F6, etc., by secondary reactions. The surface coverage of graphite fluoride on the anode depends on the relative reaction rates of equations 4 and 5. Equation 6 has been introduced to analyze the wettability of the carbon surface with graphite fluoride formed on it.2 It shows the relationship between the fraction of effective surface for equation 3 per unit surface area of carbon (a) and the contact angle (0) of a fluorine gas bubble on the surface of the carbon electrode.2... 

The authors demonstrated also the conversion of peroxides into OH functions which greatly improve the wettability of materials. It is interesting to note that the activation of the polymer by ozone is operated in fluorinated solvents (Freon 113) in which the polymer is not soluble but ozone is very soluble. 

Elemental sodium, as well as other alkali metals, reacts with perfluorocarbon polymers by removing fluorine from them. This reaction has a practical application for improving surface wettability and adhesive bonding of perfluorocarbon polymers to other substrates.57... 

The strong bonding of the fluorine ligand to most other atoms has given rise to a major interest in fluoro-coatings for surfaces and this has in turn fostered much work on the effective use of plasmas in which SFg or CF4 other kinetically inert (and hence rather safe reagents) are used as the source of F atoms. Such fluorocoatings can profoundly affect not only the susceptibility of the material to chemical attack but also the physical behavior, such as wettability and lubricity. 

Surface fluorination in various fluorinated media are currently used nowadays as processes that allow the modifications of many classes of materials, such as metals, intermetallics, semiconductors, carbons, superconductors, oxide ceramics. The above selected examples have illustrated some physical properties that can be drastically modified, including conduction, adhesion, passivation, superconductivity, hy drophobicity / wettability. 

Figure 11. Effect of progressive fluorination of oj-CH3 group on wettability by n-alkanes [32]...

Our results on the wettability of surfaces covered with highly fluorine-substituted alkyl groups stimulated several research laboratories to apply these surface properties to polymeric coating materials for textile fibers and fabrics as a means of imparting to them nonstaining, oil-, and water-resistant properties. Such products are becoming very prominent today and the contact angle is used for product control and trade specifications [1]. 

Fluorinated compoimds I, III, IV, and V were dissolved in tetra-hydrofuran solutions of the PVeC copolymer in concentrations up to 1% by weight of the polymer. Of these additives, the 3-methyl glutarate (in), ethane sulfonate (V), and tricarballylate (I) derivatives failed to modify the wettability of the polymer surface. However, the tetra-chlorophthalate derivative (IV) caused a marked decrease in the wettability of the polymer (see Table IV, last column). In Figure 3 the graph of cos 6 vs. 7lv° n-alkanes on the resulting surface shows that... 

Fluorine can be demonstrated by placing approximately 0.5 g of the plastic in a small test tube and pyrolyzing it in a Bunsen flame. After cooling, add a few milliliters of concentrated sulfuric acid. The presence of fluorine is indicated by a characteristic non-wettability of the wall of the test tube. (Make a comparison experiment with a sample of known fluorine content.)... 

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