ELECTROCHEMICAL CARBYNE FROM PERFLUORINATED HYDROCARBONS - SYNTHESIS AND STABILITY STUDIED BY RAMAN-SCATTERING

The synthesis of electrochemical carbyne from perfluorinated hydrocarb ons was optimized. The relative yield of carbyne was monitored by Rama n spectroscopy using the C=C stretching mode. The position and relativ e intensity of this band depend on the type of fluorocarbon and reduci ng agent used. Optimum conditions were attained for electrochemical re duction of poly(tetrafluoroethylene) with K- or Na-amalgams. Poly(tetr afluoroethylene) oriented by mechanical stretching gives partly orient ed polyyne chains with a conjugation length of 16 carbon atoms. Electr ochemical carbyne is stabilized against interchain crosslinking (graph itization) by interspersed microcrystalline alkali metal fluoride (rea ction byproduct). Carbyne decomposes spontaneously if the alkali metal fluoride is extracted from the composite by leaching out with water. The final salt-free product is a highly disordered carbon material res embling diamond-like amorphous carbon; it graphitizes after thermal an d pressure treatments.