Radiation-chemical synthesis and properties of tetrafluoroethylene telomeres in fluorine-containing solvents

The kinetics of radiation telomerization of tetrafluoroethylene in a series of fluorine-containing solvents was studied. A comparative analysis of their reactivity was carried out. The structure and some properties of the telomeres were studied by IR spectroscopy, thermogravimetric and elemental analysis, and electron microscopy.     

An NMR, DSC, and IR spectroscopy study of the composite formed during low-temperature postradiation polymerization of C2F4 in the presence of a 3D graphene material

By solid-state magic angle-spinning nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), and IR spectroscopy, polytetrafluoroethylene (PTFE) samples obtained by low-temperature (T = ?196°C) postradiation polymerization of tetrafluoroethylene (C₂F₄) and C₂F₄ mixtures with a 3D graphene material formed by the microwave exfoliation of graphite oxide films (MEGO) have been investigated. It has been shown that the melting point of PTFE in the PTFE-MEGO composite is 332.5°C, which is 8.8°C above the melting point of pure PTFE obtained under the same conditions. According to the measured values of specific enthalpy of melting ΔH _m (51.5 and 45.4 J/g), the degrees crystallinity (x _c) of 0.63 and 0.55 have been calculated for the pure polymer and the composite, respectively. It has been also found that none of the PTFE-containing samples examined has terminal CF₃ groups typical of PTFE prepared by conventional suspension polymerization.     

Effect of Tetrafluoroethylene Concentration on Thermophysical Characteristics and Structure of Products of Its Radiation Telomerization in Flutec PP3

High Energy Chemistry - The influence of monomer concentration on the properties of radiation-synthesized tetrafluoroethylene telomers in perfluoro-1,3-dimethylcyclohexane has been studied by...     

Radiation-initiated synthesis of tetrafluoroethylene telomers in 1,2-dibromotetrafluoroethane at a constant pressure of the monomer in the reactor

The kinetics of radiation-initiated telomerization of tetrafluoroethylene in a 1,2-dibromotetrafluoroethane solution at a constant concentration (pressure) of the monomer in the reactor was studied. The properties, molecular structure, and morphology of the telomers were studied by IR spectroscopy, scanning electron microscopy, and elemental and thermal gravimetric analyses. The synthesized telomers show promise for the development of fluoropolymeric nanocomposites and protective hydrophobic and antifriction coatings.     

Hydrophobization of Porous Ceramic Materials Based on Quartz Fibers with Solutions of Tetrafluoroethylene Telomers

Russian Journal of Applied Chemistry - Hydrophobization of highly porous heat-shielding ceramic materials based on quartz fibers was studied. Radiation-synthesized tetrafluoroethylene telomers...     

Slow oscillations of magnetoresistance in quasi-two-dimensional metals

Slow oscillations of the interlayer magnetoresistance observed in the layered organic metal beta-(BEDT-TTF)(2)IBr(2) are shown to originate from the slight warping of its Fermi surface rather than from independent small cyclotron orbits. Unlike the usual Shubnikov-de Haas effect, these oscillations are not affected by the temperature smearing of the Fermi distribution and can therefore become dominant at high enough temperatures. We suggest that the slow oscillations are a general feature of clean quasi-two-dimensional metals and discuss possible applications of the phenomenon.     

Platinum nanoparticles on fullerene black as effective catalysts of hydrogenation

Fixation of platinum from H₂PtC_l6 on fullerene black through non-conjugate double bonds or hydroxyl groups created on their base in the presence of an organic base with postreduction by formate ions allows platinum particles of size 3–4 nm to be obtained. These compositions catalyze 1-decene and nitrobenzene hydrogenation and exceed in activity the traditional catalyst Pt/C with platinum particle size of 70–80 nm. The average size of the fixed platinum particles affects the catalytic activity stronger than the specific surface area and the electron conduction of the carrying agent.     

Addition theorems of partial vector solutions of the Lame equation in a spheroidal basis

Institute of Superhard Materials, National Academy of Sciences of Ukraine, Kiev. Translated from Prikladnaya Mekhanika, Vol. 31, No. 2, pp. 86–92, February, 1995.     

Radiation synthesis of tetrafluoroethylene telomers in chlorosilanes and their use for modification of aluminoborosilicate glass fabric

The kinetics of radiation-initiated telomerization of tetrafluoroethylene in dichlorodimethylsilane and chlorotrimethylsilane have been studied, and the molecular structure and properties of the telomers have been revealed. It has been shown that the introduction of ~3.5 wt % product telomer into aluminoborosilicate glass fabric gives a fluorinated glass-reinforced polymer material with good hydrophobicity.