NEW FLUORINE-CARBON COMPOUND PREPARED BY THE DIRECT FLUORINATION OF MESOPHASE PITCH

Mesophase pitch derived from coal tar was directly fluorinated by fluorine gas in order to prepare a new fluorine-carbon compound at temperatures between 50-degrees-C and 130-degrees-C. The obtained compound (pitch fluoride) was yellowish white. The composition of the compound was estimated to be between CF1.30 and CF1.59 by elemental analysis. Though the X-ray diffraction pattern of the pitch fluoride showed that its structure was similar to that of graphite fluoride, (CF)n with low crystallinity. it had some properties differing from (CF)n. First, the pitch fluoride was soluble in some fluorosolvents, such as C6F6, C6H5CF3, etc., while the graphite fluorides are insoluble in any solvent. Second, its thermal behavior was quite different from that of (CF)n; (CF)n decomposes at temperatures higher than 500-degrees-C to amorphous carbon and gaseous fluorocarbons, such as CF4, C2F6, etc., while the decomposition products of pitch fluoride were mainly solid fluorocarbons. An attractive feature of these compounds is that the thin film of the decomposed pitch fluoride could be formed on metal substrates by means of the vacuum-vapor-deposition method. The thin film of the decomposed pitch fluoride had a larger contact angle (113-degrees) than PTFE (109-degrees) against water, indicative of lower surface energy.