Carbyne — the third allotropic form of carbon

The history of the discovery of carbyne, the chemical and physical methods used to obtain it, the analysis of its structure, and some of its properties are briefly considered. The prospects for its practical applications are discussedThis publication is based on a number of works on carbyne submitted for the Russian State Prize in the field of science and technology in 1993; performed at the A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences and the M. V. Lomonosov Moscow State University.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 450–463, March, 1993.     

m‐Xylylene bismaleimide: a versatile building block for high‐performance thermosets

m‐Xylylene bismaleimide, Compimide ? ? Compimide® is a registered trademark.
MXBI (hereafter MXBI), was developed as a building block for formulating bismaleimide resins with improved processability. MXBI on its own, or in combination with 4,4′‐bismaleimidodiphenylmethane (Compimide MDAB, hereafter MDAB) and with 2,2′‐diallylbisphenol‐A as a co‐monomer, provides very low‐melting resin blends, which can be processed at temperatures around 60–80°C via RTM (Resin Transfer Moulding), VARIM (Vacuum Assisted Resin Infusion Moulding), prepregging, and wet filament winding (FW). Uncured and cured resin properties were evaluated. The mechanical property spectrum of the MXBI/MDAB/diallylbisphenol‐A system with varying MXBI/MDAB ratio shows almost equivalent contributions of MXBI and MDAB to the mechanical properties of a system. Higher MXBI proportions are responsible for lower resin viscosities and hence superior processability. Copyright © 2015 John Wiley & Sons, Ltd.     

Inhomogeneous depth distribution of fluorine atoms in PVDF upon radiative carbonization

Under the action of ionizing radiation on a PVDF film, fluorine and hydrogen atoms bound to its linear carbon chain with single chemical bonds detach. Free atoms and HF molecules diffuse toward the film surface and escape from it. As a result of irradiation of the sample surface, a fluorine concentration depth profile arises. The fluorine distribution in the PVDF films subjected to long-term X-ray exposure was studied using X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. Both methods yield close values of the fluorine concentration at a depth of ～10 nm.     

Influence of structural defects on the intensity of carbon emission spectra

The influence of atomic ordering defects on the integrated characteristics of photoelectron and Auger spectra of various carbon objects is studied. The analysis of the data indicates that there is a correlation between the type of hybridization of valence electrons and the relative intensity of photoemission of the core electrons and Auger emission. The results obtained on a fullerene sample support the existence of fractional types of hybridization.     

IR Spectra of Carbynoid Films Prepared by Dehydrofluorination of Polyvinylidene Fluoride

IR and X-ray photoelectron spectra of the products of chemical carbonization of polyvinylidene fluoride were recorded and discussed.     

Modification of X-ray excited photoelectron and C KVV Auger spectra during radiative carbonization of poly(vinylidene fluoride)

Modifications of the photoelectron and C KVV Auger spectra during the long-term surface degradation of partially crystalline PVDF under simultaneous soft X-ray and electron followed by ion irradiation are reported. Deep radiative carbonization brings about the formation of carbynoid structures (chain-like carbon) in the surface, while the number of interchain cross-links is insignificant. As a result, the shape of the electron emission spectra of carbon in the carbonized sample essentially differs from that of graphite and PVDF. The ion bombardment of the carbonized sample destroys one-dimensional structure due to the formation of cross-links. Thus, carbon atoms transit into sp²-hybrid state and, therefore, the photoelectron and Auger spectra show features characteristic for microcrystalline graphite.     

On the theory of stoichiometric binary compound films by reactive magnetron sputtering

The theoretical model of reactive sputtering of binary compounds has been improved; the model makes it possible to calculate the stoichiometry condition for these compounds by taking into account the adhesion of molecules of the reacting gas at the regions of the surface occupied by a binary compound, followed by their diffusion to free titanium atoms. It is shown that surface diffusion of reacting gas molecules facilitates the formation of a stoichiometric binary compound, stabilizes the sputtering process, increases its rate, and makes the synthesis of the binary compound on a getter prevailing over cathode sputtering of this compound.     

Structural transformations of the cumulene form of amorphous carbyne at high pressure

Structural transformations of the cumulene form of amorphous carbyne which are induced by heating at high pressure (7.7 GPa) are investigated. These can be described by the sequence amorphous phase — crystal — amorphous phase — disordered graphite. Raman scattering shows that predominately the chain structure of carbyne remains at the first three stages. It was found that the intermediate crystalline phase is an unknown modification of carbon whose structure is identified as cubic (a=3.145 Å). A mechanism of structural transformations in carbyne that involves the formation of new covalent bonds between chains is discussed. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 237–242 (25 August 1997)     

Synthesis of nanocrystalline titanium dioxide films in a cylindrical magnetron-type gas discharge and their optical characterization

The plasma-dynamic and spectral characteristics of a cylindrical magnetron-type gas discharge are studied experimentally. The radiation spectrum of the plasma is recorded in real time in the range 350–820 nm. Appropriate conditions for synthesis of TiO₂ binary compound are found. They are provided by maintaining the intensities of the spectral lines of reactants and a plasma-forming gas at a desired level. The feasibility of monitoring the TiO₂ film synthesis conditions from the spectral characteristics of the discharge plasma and from the variation of the discharge voltage is considered. Ellipsometric and spectral data for nanocrystalline titanium dioxide films indicate that the refractive index of the film depends on its thickness.     

On the possibility of synthesizing one-dimensional carbon during radiative carbonization of PVDF

The modification of x-ray photoelectron spectra (XPS) and C KVV spectra of a partially crystalline polyvinylidene fluoride (PVDF) film under the long action of soft x-rays and secondary electrons followed by argon ion bombardment of its surface is investigated. Deep radiative carbonization leads to the formation of carbynoid structures (chain carbon) on the PVDF surface. Hence, the carbon XPS of the carbonized sample differs from those obtained for graphite and PVDF. Ion bombardment shows the instability of the carbonized sample surface, giving rise to formation of sp ² hybrid bonds of carbon atoms. The obtained results are indirect experimental evidence that, before ion bombardment, sp-type bonds are dominant on the carbonized PVDF surface.