Controlled modification of polyvinylidene fluoride as a way for carbyne synthesis

Abstract

In the present work, the possibility of carbyne synthesis by modifying polyvinylidene fluoride (PVDF) with synchrotron radiation was investigated for the first time. The analysis of the kinetic dependences of the CF2 groups' loss in PVDF was done, and the mechanism of dehydrofluorination of PVDF under the action of monochromatic X-ray radiation of various energies was elucidated. As a result, the two-stage model for the process of PVDF carbonization was proposed. According to it, first one fluorine atom and one hydrogen atom are split off and removed in the form of an HF molecule with the formation of a double carbon-carbon bonds (CFCH). Second, the formation of carbyne occurs, in which carbon atoms are connected in a chain by means of either double carbon-carbon bonds (CC) or alternation of carbon single and triple bonds (CC). A joint analysis by high-resolution near-edge X-ray absorption fine structure (NEXAFS) spectra and X-ray photoelectron spectra made it possible to put forward a hypothesis that, by irradiating the polymer with photons of monochromatic X-ray radiation with a given energy, it is possible to achieve the formation of uniform layers of amorphous carbyne of various depths, which offers a challenge of producing a next generation of devices for carbon and 1D nanoelectronics.