Radiation-chemical synthesis of tetrafluoroethylene telomers and their use for preparation of thin protective fluoropolymer coatings

The specific features and possibilities of preparation of protective coatings and composite materials based on fluoromonomers using high-energy rays (⁶⁰Co γ-rays, fast electrons) were analyzed. The emphasis was placed on synthesis and application of tetrafluoroethylene telomers in acetone. The structure and properties of telomers were examined by IR and NMR spectroscopy, as well as by X-ray diffraction analysis and diathermy. The radiation initiation allows preparation of new products with a broad spectrum of functional properties and opens wider prospects for technological application of fluoromonomers.     

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 synthesis of telomers at a constant tetrafluoroethylene concentration in acetone

Radiation-initiated polymerization of tetrafluoroethylene (TFE) in acetone has been carried out in a specially designed reactor, which makes it possible to maintain a constant concentration of the monomer in a solution during synthesis. The features of the telomerization process at different initial concentrations (pressures) of TFE have been studied. Concentrated solutions of telomers have been obtained. The carrying out of the process at different pressures in the reactor makes it possible to obtain telomers differing in molecular mass and thermal resistance.     

Gas chromatographic properties of tetrafluoroethylene telomers

The paper describes an investigation of the gas chromatographic properties of tetrafluoroethylene telomers of general formula F(CF₂)_nI, Br(CF₂)_nBr, Br(CF₂)_nI, I(CF₂)_nI and (CF₃)₂CF(CF₂)_nI. The telomers are well resolved on columns with squalene, silicone oil or tritolyl phosphate stationary phases, and relative retention volumes are given for these three columns. The temperature dependence of the relative retention volumes of F(CF₂)_nI and Br(CF₂)_nBr telomers has been investigated. The relative retention volumes are correlated with the telomer boiling points, and with structural features of the telomers.     

Radiation synthesis of tetrafluoroethylene telomers with functional hydroxyl and amino end groups in Freon 113

The kinetics of radiation telomerization of tetrafluoroethylene in Freon 113 with ethanol and ammonia additives have been studied by kinetic calorimetry. Tetrafluoroethylene telomers with terminal hydroxyl and amino groups have been obtained. The molecular structure, properties, and composition of the telomers have been investigated by IR spectroscopy, thermogravimetry, and elemental analysis.     

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.     

Structure of fluoropolymer products prepared from solutions of tetrafluoroethylene telomers

The molecular and morphological structures of fluoropolymer products obtained by deposition of tetrafluoroethylene telomers from acetone solutions on substrates have been studied by IR and NMR spectroscopy, X-ray powder diffraction, and atomic force microscopy. The molecular structure of the basic element of the sample is similar to that of PTFE, even though this element is composed of shorter chains carrying CH₃-C=O-CH₂ end groups. The supramolecular structure of the sample differs from that of PTFE by the character of disorder and a lower degree of crystallinity. Coatings obtained from solutions of tetrafluoroethylene telomers are of the island pattern with strongly overlapped regions.     

Surface modification of cellulose-containing materials with solutions of tetrafluoroethylene telomers

Russian Journal of Applied Chemistry - Modification of cellulose-containing materials (wood veneer, paper) with solutions of radiationsynthesized tetrafluoroethylene telomers was studied. Treatment...     

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.     

Determination of the molecular masses of tetrafluoroethylene telomers by gel-permeation chromatography

Gel-permeation chromatography has been employed to study the molecular-mass distribution of tetrafluoroethylene telomers prepared through γ irradiation of 0.05–0.56 mol/l monomer solutions in acetone. The molecular-mass-retention-volume V _R calibration dependence has been plotted from chromatograms of perfluoroenanthic and perfluoropelargonic acids (F(CF₂-CF₂) _n COOH; n = 3 or 4, respectively). The measured V _R-log n curve is located parallel to that plotted earlier for oligo(oxyethylene glycol)s (OH-(CH₂-CH₂O) _n -OH) and is shifted along the volume axis. The shift value is determined by the ratio between logarithmic volumes of chain units of these oligomers. The shift agrees with the assumption that the retention volumes of oligomers with the same spatial chain structure are proportional to the logarithm of the ratio between their van der Waals volumes. This assumption is supported by the quantum-chemical calculation of the molecular volumes of oligomers composed of (CH₂-CH₂) _n , (CH₂-CH₂O) _n , and (CF₂-CF₂) _n fragments. As the concentration of tetrafluoroethylene in the initial solution is increased, the average length of (CF₂-CF₂) _n chains increases from \(\bar n\) ≈ 3 to \(\bar n\) ≥ 8. The maximum values of n = 12–15 are determined by the solubility limit of telomers in THF.     

Preparation and properties of composites based on caramelized aluminoborosilicate fabric and tetrafluoroethylene telomers

New composites based on activated caramelized aluminoborosilicate glass fabric and radiationsynthesized tetrafluoroethylene telomer solutions were prepared, and their properties were studied. The properties of materials prepared from standard commercial and caramelized glass fabrics were compared.     

Quantum-chemical simulation of the nanostructure of colloid particles and gels of tetrafluoroethylene telomers in acetone

The telomers H(C₂F₄) _n CH₂COCH₃, where n = 3,7; their complexes with acetone molecules; and the entities composed of two complexes were calculated by the quantum-chemical method of the density functional theory using the software program Priroda. The existence of two configurations of the complexes with the bond energies of 2 to 6 kcal/mol per acetone molecule was established. The bonding of acetone molecules with the macroradical during the chain transfer reaction ensures the spatially correlated arrangement of telomers and leads to the formation of a network, which determines the internal structure of both colloid particles and the gel into which the colloid particles transform with an increase in the network density.     

NMR identification of the terminal groups of the telomers of tetrafluoroethylene with tetrahydrofuran

¹H, ¹³C, and ¹⁹F high-resolution NMR spectra with heteronuclear spin-spin decoupling and without it were recorded for identification of the terminal groups of oligomers obtained by radical polymerization of tetrafluroethylene (TFE) in tetrahydrofuran (THF) solutions. The analysis of the spectra and their comparison with the quantum-chemically calculated spectra of possible polymerization products led to the conclusion that the terminal groups of oligomers are the α radical of THF and the hydrogen atom. The structure of oligomers found in this study opens up an opportunity of synthesizing from them polymers consisting of a flexible main chain with substituents in the form of rigid perfluorinated rods.     

Application of infrared spectroscopy to investigation of the structure of tetrafluoroethylene telomers in acetone and their intermolecular interaction

Measured FTIR spectra of the products of the radiation-chemical telomerization of tetrafluoroethylene in acetone have been compared with the spectra calculated by density functional theory for oligomers with the structural formula H(C₂F₄) _n CH₂COCH₃, n ≥ 3, and the dimer of the latter. Inhomogeneous broadening, splittings, and shifts of the CH, CC, and CO vibration bands in the terminal groups on the oligomers relative to the associates of acetone molecules confirm the structural formula of the oligomers and show that strong hydrogen bonds are formed between their end groups.     

Radiation-chemical processes in polyorganosiloxanes

Radiation-induced changes in polymethylphenylsilsesquioxane block copolymers were studied. It was found that a pregel was formed at doses of 30–50 kGy and gel formation mainly occurred in polydimethylsiloxane (PDMS) blocks. The UV spectrophotometry of samples in a cyclohexane solution demonstrated that, at doses of 10–50 kGy, a noticeable broadening of absorption bands due to phenyl groups was observed only in oligophenylsilsesquioxane and not in the block copolymers. Hydrogen atoms formed in the radiolysis of PDMS did not reach polyphenylsilsesquioxane blocks.     

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.