Fluorocarbon

Fluorocarbons are a group of substances in general industrial use of language users and processors, not a specific chemical substance group. As a community, these substances contain perfluorinated carbon chains, but not always exclusively. The most important feature is the water-repellent (hydrophobic ) nature of these substances. The term derives from the English fluorocarbon ( s ).

Properties

Perfluorocarbons caused by complete replacement of the hydrogen atoms in hydrocarbons by fluorine. These are among the hydrofluorocarbons ( HFCs) called. The end of such a long-chain compound

... - ( CF2 ) n- CF3

Only shows water repellency ( hydrophobicity ), when n is greater than 3. This effect generally occurs in fluorous phases.

In polymeric compounds so that there is the possibility, in place of the fluorination of the backbone ( such as in polytetrafluoroethylene, PTFE) installed laterally shorter perfluorinated radicals, to produce a sufficient hydrophobicity as corresponding polyacrylates containing Fluorcarbonacrylaten as copolymerisation. Fluorocarbons contain a few exceptions, no other halogens.

Applications

By the hydrophobic character of the fluorocarbons are those suitable for the manufacture of very effective surfactants and metal cleaners. Derivatives of perfluorinated alkane sulfonic acids are also used for impregnation ( water and oil repellent) of textiles, leather and paper.

As polymeric compounds both thermoplastics and elastomers ( fluorine rubber, perfluororubber ) are known. Remarkable are the high heat and chemical resistance, continuous operating temperatures of 250 ° C and higher, the electrical insulating properties, non-flammability, low adhesion to most materials and - by extension - a very good lubricity. Applications include because of the high prices of the materials mainly areas in the high power range: Linings of cookware, chemical apparatus and pipes, insulation of cables and wires, gaskets, O- rings, films and tubes, apparatus and engine, air and space travel. Fishing Lines of fluorocarbons with the same refractive index as water are virtually invisible to fish and allow for higher quotas. In the U.S., they are widely used. As strings for musical instruments contribute fluorocarbons to improved sound at.

One of the most prominent representative is polytetrafluoroethylene ( PTFE), known worldwide under the trade name Teflon ®, a thermoplastic with a high melting point of about 300 ° C. It is chemically hardly vulnerable and finds many applications in the home and technology. Derivatives of perfluorinated Carbonen also be used in doping in order to store more oxygen in the blood can.

Examples

Polyvinylidene fluoride ( PVDF), formula ( -CH2- CF2 - ) n, less heat resistant than PTFE, but excellent in resistance to Bewitterungseinflüssen and long lifetime (≥ 20 years). Therefore, PVDF is also used in paints for coating of facade elements in the construction industry such as steel or aluminum in coil coating process.

Perfluoroalkoxy polymers ( PFA), thermoplastic copolymers of tetrafluoroethylene with perfluorinated vinyl ethers having high heat resistance and long-term temperature of use higher than 250 ° C.

Polychlorotrifluoroethylene (PCTFE ), formula ( - CF2 - CFCl - ) n, Thermoplastic, because of the chlorine component not as durable as PTFE, but can be more easily processed.

Copolymers of perfluoroalkyl methacrylates and are also referred to as fluorocarbons. These connections for the water-repellent finishing of textiles are known.

Fluoroelastomers, such as fluorine rubber are not crystalline, elastomeric polymers such as silicones, perfluorinated or fluorinated copolymers of different monomers and optionally with ethylene or propylene. Fluorinated ethylene propylene copolymer ( FEP) is used, for example, in water-repellent coatings for flexible substrates. The higher the fluorine content, the better the heat resistance. Applications are also seals and O- rings in the engine.

Perfluoropolyether ( PFPE ) is used as resistant lubricant and as an inert heat transfer during vapor phase soldering.