G. A. Kichigina

Tetrafluoroethylene telomers: Radiation-initiated chemical synthesis, properties, and application prospects

Systematic studies devoted to the radiation-chemical synthesis of solutions of tetrafluoroethylene telomers in various solvents are summarized. The properties and application prospects of tetrafluoroethylene telomers are considered. Radiation initiation allows new functional products with a broad spectrum of properties to be obtained and new technological approaches with the use of fluorinated polymers to be developed.

Radiation Telomerization of Tetrafluoroethylene in Butyl Chloride Solution

The kinetics of the radiation-initiated polymerization of tetrafluoroethylene (TFE) in butyl chloride has been studied. The rate of the process, the properties and yield of telomers obtained depend on the initial concentration of TFE (2.6–22 wt %) in the solution and the dose of γ-irradiation. The analysis of the measured IR absorption spectra and a possible scheme of the process allow to suggest that the main product of the reaction is C4H8Cl(C2F4)n−1CF2CF2H with the formation of small amounts of C4H9(C2F4)n−1CF2CF2H and Cl(C2F4)n−1CF2CF2H. The average number of links in the telomer (n) increases from 7.6 to 16.1 when the concentration of the monomer in the solution varies in the range of 7–22 wt %. The length of the chain of the soluble telomers (n) does not depend on the initial concentration of TFE and makes ∼7.

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.

Radiation-initiated telomerization of tetrafluoroethylene in 1,2-dibromotetrafluoroethane

The kinetics of the radiation telomerization of tetrafluoroethylene in 1,2-dibromotetrafluoroethane has been studied. It has been shown that the process occurs very efficiently in the perfluorinated solvent; small doses of γ-radiation (~2 kGy) are required for the complete conversion of the monomer. Telomers with a chain length of 120–360 tetrafluoroethylene units and high thermal stability are formed in the reaction. The structure and properties of the telomers have been studied by IR spectroscopy, thermogravimetry, and elemental analysis.

The Specifics of Radiation Telomerization of Tetrafluoroethylene in Chlorinated Solvents and Telomer Properties

Radiation telomerization of tetrafluoroethylene in butyl chloride, chloroform, and carbon tetrachloride has been investigated. The chain length of telomers and their solubility and thermal stability depend on the initial monomer concentration and telogen properties. In the case of telomerization in chloroform and carbon tetrachloride, the yield, the chain length, and the thermal stability of the telomers are significantly higher than those in butyl chloride, in which the process is less efficient but soluble telomers having a short chain length and exhibiting quite high thermal resistance are produced. The molecular structure of the telomers has been studied by IR spectroscopy.

Hydrophobization of polyester textile materials with solutions of tetrafluoroethylene telomeres synthesized in acetone and butyl chloride: Properties and structure of coatings

This article is devoted to the analysis of the surface properties of polyester textile materials modified with the tetrafluoroethylene telomeres synthesized in acetone and butyl chloride in order to impart high hydrophobicity to the materials. The particularities of the morphology of the formed hydrophobic coatings in the case of the use of various solutions of tetrafluoroethylene telomeres have been demonstrated using atomic force microscopy (AFM). The dependencies of the characteristics of the hydrophobicity of the modified textile materials on the structure of the coatings have been analyzed. The resistance of the coatings to the operational impacts has been determined.

Low-temperature radiation telomerization of tetrafluoroethylene in hexafluoroisopropanol

The kinetics of low-temperature (180–270 K) postradiation telomerization of tetrafluoroethylene in hexafluoroisopropanol has been investigated. The efficiency of the process is determined by the initial concentration of the monomer in the solvent and the dose of preliminary irradiation. It has been shown that the telomerization reaction proceeds via the radical mechanism during the devitrification of the system. Active centers that initiate the process and their yield at 77 K have been studied by the ESR technique. Some properties of the product telomers have been studied.

Radiation telomerization of tetrafluoroethylene in chlorinated telogens at a constant reactor pressure

The kinetics of the radiation-initiated telomerization of tetrafluoroethylene (TFE) in the solutions of telogens (butyl chloride, chloroform, methylene chloride, and carbon tetrachloride) at a constant monomer pressure in the reactor was studied. In the course of the Γ-irradiation of the reaction mixture, TFE telomers containing repeatedly soluble and insoluble fractions were formed. In chloroform, methylene chloride, and carbon tetrachloride, the rapidly occurring process of the synthesis of insoluble telomer made the main contribution to the total yield of products. For the solutions of TFE in butyl chloride, the rates of formation of soluble and insoluble telomers were almost the same. The average chain length and the thermal stability of the resulting telomers were evaluated.

The self-sustained-wave regime of cryocopolymerization for filler-containing systems

For a filler-containing monomer, features of solid-phase self-sustained-wave regimes of cryocopolymerization initiated by the brittle failure of preradiolyzed samples are studied. Experiments performed with the model system acetaldehyde-alumina allow the proposal that the procedure can be created for the manufacture of polymer composite materials at low and ultralow (4.4–77 K) temperatures during the traveling-wave regime with the use of energy of cosmic and solar radiation for activation of the frozen monomer matrix.

Use of solutions of radiation-synthesized telomers of tetrafluoroethylene to modify glass fiber

In this work, we have suggested a new approach to fabricating fluorine-containing glass fibers based on the infiltration of glass-fiber filler by radiation-synthesized telomer solutions of tetrafluoroethylene. The radiation-chemical synthesis of tetrafluoroethylene telomers has been carried out in some solvents, their thermal stability has been studied, and the effectiveness of various telomers has been evaluated.