Fluorocarbon Compounds Research Articles

Pathochemical Toxicity of Perfluorocarbon-5070, a Liquid Test Performance Fluid Previously Used in Dialyzer Manufacturing, Confirmed in Animal Experiment

In the light of clustered deaths in late 2001 associated with hemodialysis (HD), this article analyzes the pathochemical toxicity of the perfluorocarbon-5070 (PF-5070), a liquid used as test performance fluid for detecting capillary leaks during dialyzer manufacturing. Residual PF-5070 in some Athane dialyzers of the involved brands was infused in the injured patients during hemodialysis. The clinical presentation was in contrast with other previously described severe reactions to HD. Foam material was discovered in the right ventricle and caval vein of the patients who underwent postmortem examination. Deaths were attributed to gas embolism without the external causes identified. To explore the pathochemical toxicity of the inert liquid PF-5070, an animal model was developed. In a rabbit model, single slug intravenous injections as bolus of increasing doses of PF-5070 were performed. In a first set of experiments, three groups of three rabbits were administered increasing doses of PF-5070 at 4, 40, or 160 microl/kg. After intravenous injection, the animals were observed for clinical signs of adverse effects and underwent autopsy after death. Doses were normalized to animal body weight to allow comparison with supposed patient exposure. Five of nine rabbits died soon after PF-5070 dosing: One rabbit died within 4 h in the 4 microl/kg group, one rabbit died within 30 min in the 40 microl/kg group, and three rabbits died within 30 min in the 160 mul/kg group. In a second set of experiments, six rabbits were injected with a lethal dose of PF-5070 to analyze clinical symptoms and pathophysiology. All rabbits died on the day of dosing and displayed neurologic disorders (paralysis, nystagmus, rigidity, convulsions), then breathing abnormalities (rapid breathing, salivation, dark mucous membrane), and fatal collapse. Autopsy of rabbits showed evidence of gas retention in the lung tissue and gas bubbles in the right cardiac cavities. Histologic findings included alveolar hemorrhage with pulmonary edema, cerebellum, and cortex patchy areas of infarction. Single-dose intravenous administration of PF-5070 reproduced in a rabbit model the pathophysiologic effects observed in the hemodialysis patients. Severity of the symptoms observed in the animals was dose-dependent. Clinical and pathologic findings can be explained by the capacity of perfluorocarbon to emulsify blood at body temperature, to increase partial pressure in the pulmonary capillary bed, and to form bubbles in the pulmonary capillary circulation, thus blocking lung and visceral perfusion. Such experimental findings indicate the toxicity of PF-5070 administered intravenously and make the pathochemical toxicity link with the hemodialysis-related deaths caused by the presence of residues of PF-5070 in the Althane dialyzers. We conclude, in light of this outbreak and the subsequent investigations, that liquid PF-5070 is a highly toxic compound when administered intravenously because of its emulsifying properties. The use of PF-5070 or any liquid fluorocarbon compounds in medical devices with blood contact and particularly in the dialyzer manufacturing should be considered with caution.

The effect of moisture content on retention of fluorocarbon tracers on sand

Several fluorocarbon compounds have been evaluated as geothermal tracers in sand column tests using damp, dry, and untreated ‘washed sea sand’. Fluorocarbons evaluated in these tests included two hydrofluorocarbon freons: trifluoromethane (R23) and 1,1,1,2-tetrafluoroethane (R134a), and five perfluorocarbons: perfluorodimethylcyclobutane, perfluoromethylcyclopentane, perfluoromethylcyclohexane, perfluorodimethylcyclohexane and perfluorotrimethylcyclohexane. Transport of the fluorocarbon compounds was explored in flowing helium at 23 and 60 °C. This work found that fluorocarbon retention is strongly affected by sand moisture content. The fluorocarbon compounds flowed with the bulk fluid when the sand was damp, but were significantly retained by the solid phase when the sand was thoroughly dried. The data suggest that the fluorocarbons may be conservative tracers in geothermal conditions up to mild superheat but they may not be conservative at geothermal conditions with a high degree of superheat.

Influence of vapors of volatile organic compounds on spectral shift of bending vibrations of freely suspended ferroelectric liquid-crystal films

The influence of the vapors of volatile inert fluorocarbon compounds on the mechanical properties of freely suspended ferroelectric liquid-crystal films has been studied. It was shown that spectral shift of bending vibrations of freely suspended films depends on the mass variations of the associated ambient gas as well as on the adsorption of the vapors of volatile fluorocarbon compounds onto the film surface. It was also shown that adsorption layers similar to surfactants decrease the film surface tension by 11%–35% (4–12.5 dyn/cm).

Perspective on Fluorocarbon Chemistry.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Perspective on fluorocarbon chemistry.

Fluorocarbons, organic molecules with carbon skeletons and fluorine "skins", differ fundamentally from their hydrocarbon counterparts in interesting and useful ways. A selection of the myriad applications fluorocarbons and their derivatives have found in modern life is described and related to molecular properties. Salient aspects of the nature and reactivity of fluorocarbon compounds are highlighted by comparison with their more familiar hydrocarbon analogues.

Temperature Dependence of Hamaker Constants for Fluorocarbon Compounds

The effect of temperature on the liquid−vapor surface tension of fluorocarbon and hydrocarbon compounds starting from van der Waals interactions (calculated according to Lifshitz's theory) is studied. The correlation obtained is based on the reversibility of the process of separation of two liquid slabs, creating an intermediate vapor phase. The resulting surface tension can be expressed as a function of two surface potentials having simple dependences on temperature. Reasonable distances of closest approach between the slabs are obtained for all cases, including dispersion contributions between the molecules of water as a special case.

Microvascular gas embolization clearance following perfluorocarbon administration

Effective treatment of vascular gas embolism may be possible with emulsified fluorocarbon compounds. We tested the hypothesis that a fluorocarbon emulsion delivered before gas embolization would enhance bubble motion through the vasculature, favoring more rapid clearance. Air microbubbles were injected into the rat cremaster microcirculation in six groups of rats receiving Perftoran, an emulsified fluorocarbon, or saline immediately before, 2 h before, or after bubble injection. Embolism dimensions and dynamics were observed by using intravital microscopy. Surface area at lodging was equal between groups. Bubbles having smaller volume embolized smaller diameter vessels in the Perftoran pretreatment groups. A higher incidence of bubble dislodgement and larger distal displacement occurred in these two groups, with a 36% decrease in the time to bubble clearance and restoration of blood flow. Intravascular emulsified fluorocarbon administration before gas embolization affected initial bubble conformation, increased bubble dislodgement, and resulted in bubble displacement further into the periphery of the microcirculation. These dynamic events did not occur if embolization preceded fluorocarbon administration.

Interactions of fluorocarbon-modified poly(acrylic acid) with a cationic fluorocarbon surfactant

Abstract The physicochemical properties of mixed systems of fluorocarbon-modified poly(acrylic acid) (FA) with a cationic fluorocarbon surfactant, bis(2-hydroxyethyl)(2-hydroxy-3-perfluoro-octylpropyl)methylammonium chloride (DEFUMAC), have been investigated by surface tension, fluorescence, solubility, and 19F NMR spin–lattice relaxation measurements. The result obtained from the surface tension measurement indicates that surface DEFUMAC–FA complexes are formed by strong electrostatic attraction at pH 10, while they are formed by hydrogen bond at pH 4. However, hydrophobic interaction is hardly observed at both pHs. In the bulk properties estimated from fluorescence and solubility measurements, DEFUMAC–FA complexes exhibit large solubility capacity for fluorocarbon compounds when the content of fluorocarbon in FA increases. Moreover, the result obtained from the spin–lattice relaxation time measurement suggests that the mobility of hydrophobic end group of DEFUMAC for DEFUMAC–FA complex at pH 10 is more restricted than that at pH 4.

Permeation of single and mixed gases through composite membranes prepared by plasma polymerization of fluorocarbon compounds

The permeations of simple permanent gases and their mixtures through plasma-polymerized composite membranes were studied. Composite membranes were prepared by the plasma polymerization of fluorocarbon monomers such as pentafluorotoluene (PFT) and pentafluoropyridine (PFP) onto porous Celgard. For pure gases, the permeability coefficients were mainly affected by diffusivity rather than solubility. The permeability coefficient decreased as the kinetic molecular diameter of the penetrant molecules increased, and the permeability coefficients were independent of pressure. For mixed gases, the permeability coefficient was not affected by the composition of penetrants for the whole range of composition.

Study on thermal degradation mechanisms of comb polyacrylates containing long fluorocarbon side chains by TG/FTIR

Thermal degradation of two series of polyacrylates containing long fluorocarbon chains [abbr.: PF n A (HCF 2 (CF 2 ) n-1 -CH 2 O-C(=O)-, n = 4, 6, 8, 10) and abbr.: PFF n EA (CF 3 (CF 2 ) n-1 -CH 2 CH 2 -O-C(=O)-, n = 6, 8, 10)] was investigated by TG /FTIR. Thermal degradation behavior of polymers changed depending on the type of tie groups, which link the fluorocarbon chains to the main chain, and also on the length of fluorocarbon chains. It was clarified that the apparent activation energies (ΔE α ) of PF n A series obtained by Ozawa's method varied in the order of PF 4 A > PF 6 A > PF 8 A > PF 10 A, while those of PFF n EA series having tie group of -CH 2 -CH 2 -O-C(=O)- were almost constant. The results for PF n A series (tie group: -CH 2 -O-C(=O)-) are attributable to the shield effect of long fluorocarbon chains on the back-biting reaction in the thermal degradation of comb polymers rather than the change of C-C bond dissociation energy in the main chain. It was found that TG curves of PFF n EA series were shifted to the lower temperature region than those of PF n A. This result can be attributable to the scission of side groups followed by the evaporation of fluorocarbon compounds and carbon dioxide.

Plasma surface treatment of poly(acrylonitrile) films by fluorocarbon compounds

This paper concerns the use of the low-pressure plasma process to confer an hydrophobic character to poly(acrylonitrile) films, without altering their bulk properties. Plasma based fluorination processes using saturated fluorine compounds such as CF 4, C 6F 14 and mixtures CF 4/H 2 were used. Such treated polyacrylonitrile films were characterized by XPS analysis, infrared (ATR) spectroscopy and contact angle measurements. The use of CF 4 led to the fluorination of the film surfaces. Indeed, XPS spectra showed the presence of -CHF-, -CF 2- and -CF 3 groups. Moreover, the contact angle θ which was 63° for untreated PAN films increased to 115°. Fluorine incorporation in the PAN disappeared when hydrogen is added to CF 4. In the case of treatment by C 6F 14, fluorination was accompanied by a polymerization, as evidenced by XPS with the disappearance of the N 1s photopeak corresponding to the C≡N functions in PAN. By considering the deposition of F- containing layer thickness, it was possible in this latter case to follow the surface modifications by ATR-i.r. spectroscopy.

Intermediate species profiles in low pressure premixed flames inhibited by fluoromethanes

We have investigated premixed 10 torr methane/oxygen flames containing CH 3F, CH 2F 2, CHF 3, and CF 4. Profiles of temperature and CH∗ chemi-luminescence were acquired, and laser-induced fluorescence (LIF) was used to obtain profiles of the intermediate species H, OH, CH, CF, CHF, CF 2, and CF 2O. The fluoromethanes were added in amounts such that each flame had the same flux of fluorine atoms. In the flames containing CH 3F, CH 2F 2, and CHF 3, the methane flow was adjusted to give an equivalence ratio of 1.07 for all three inhibited flames. The experimental intermediate profiles were compared to predicted profiles calculated from a hydrofluorocarbon kinetic mechanism recently developed at NIST. No fluorinated intermediates were detectable in the CF 4 inhibited flame, indicating that this agent does not react significantly under the flame conditions studied. The temperature profiles, H atom profiles, and OH profiles for the other three fluoromethane inhibited flames are nearly identical, indicating that flames containing different fluorocarbon compounds, but identical proportions of fluorine atoms, have similar structures. The kinetic model correctly predicts the location of the reaction zone in the flames containing CH 2F 2 and CH 3F. In the CHF 3 flame, however, the location of the reaction zone is predicted to be too far above the burner surface, and concentrations of H and OH are too low. The discrepancy appears to be due to pressure dependence and third body efficiencies of the agent thermal decomposition. Furthermore, relative amounts of CF, CH, CF 2, and CHF in the different flames are not very well predicted. In general, partially fluorinated methyl and methylene radicals appear to have a greater than predicted propensity to lose hydrogen atoms rather than fluorine. We propose modifications to the fluorine mechanism to correct the discrepancies observed in the low pressure experiments, while simultaneously achieving good agreement with atmospheric pressure flame speed data in CH 4/air/CHF 3 flames, and, except in rich conditions (φ > 1.25) CH 4/air/CH 2F 2 flames.

Fluorinated Amorphous Carbon Thin Films for Multilevel Interconnections of Integrated Circuits.

Fluorinated amorphous carbon thin films (a-C:F) for low-dielectric-constant interlayer dielectrics were deposited by helicon-wave plasma-enhanced chemical vapor deposition using fluorocarbon compounds as a source material. The a-C:F films could be grown from C4F8 at a high deposition rate (above 400nm/min) and they were thermally stable up to 300°C. The addition of bias power to the substrate made it possible to completely fill gaps in the wiring (space 0.35μm, height 0.65μm) with the a-C:F film. To protect the a-C:F film during further processing, we deposited a SiO2 film to add mechanical strength and resistance to the oxygen plasma used to remove resist materials. The adhesion between the a-C:F and SiO2 films was dramatically improved by inserting an adhesion promoter consisting of a-C:H and Si-rich SiO2.

Application of Fluorinated Amorphous Carbon Thin Films for Low Dielectric Constant Interlayer Dielectrics

Fluorinated amorphous carbon thin films (a-C:F) for use as low-dielectric-constant interlayer dielectrics are deposited by helicon-wave plasma-enhanced chemical vapor deposition using fluorocarbon compounds as a source material. The a-C:F films can be grown from C4F8 at a high deposition rate (above 400 nm/min) and they are thermally stable up to 350°C. The addition of bias power to the substrate makes it possible to completely fill gaps in the wiring (space 0.35 µm, height 0.65 µm) with the a-C:F film. To protect the a-C:F film during further processing, a SiO2 film is deposited to add mechanical strength and resistance to the oxygen plasma used to remove resist materials. The adhesion between the a-C:F and SiO2 films is dramatically improved by inserting an adhesion promoter consisting of a-C:H and Si-rich SiO2. By using the a-C:F and SiO2 dielectrics and chemical mechanical polishing (CMP) process, globally planarized 3-level metallization is achieved. The a-C:F dielectric can reduce inter-line capacitance close to a half value as compared with the conventional SiO2 dielectrics.

Investigation of the low-pressure plasma-chemical conversion of fluorocarbon waste gases

The kinetics of the plasma-chemical conversion of a number of saturated, as well as of unsaturated, fluorocarbon compounds is studied in an oxygen-based rf discharge by FTIR spectroscopy. Unsaturated fluorocarbons are rapidly converted into CF4 and C2F6, which, in the presence of silica walls, are finally converted quantitatively into SiF4 (etch reaction). The results of this investigation are used to design a plasma-chemical reactor for the conversion of fluorocarbon exhaust gases into SiF4 in the vacuum line of a technological low-pressure plasma reactor. Furthermore, it is shown that the primary conversion product SiF4 can be effectively converted into CaF2 in a heterogeneous reaction with a CaO/Ca(OH)2 absorber, also in the low-pressure line of the pumping system.

Characterization of fluoroelastomer networks: II. SEC, FTIR, and ODR analysis

The role of an accelerator in the nucleophilic cure of fluorocarbon compounds was further examined by preparing materials without a crosslinker. Under the previously used curing conditions, ODR reveals the formation of a secondary, accelerator-induced network that is unstable at slightly higher temperature, i.e., ≥190°C. Increased crosslink density and color are observed with the cure time, indicating slow curing reactions and likely formation of conjugated unsaturation. SEC of selective solvent-soluble fractions derived from specimens obtained from the key cure stages shows initially a falling refractive-index response. However, this change is followed by a shift in MWDs toward lower average molecular weights. On the other hand, infrared examination shows a continuous increase in the 1718 cm−1 absorption, but no major presence for the 1680 cm−1 absorption seen in the previous study in the presence of a crosslinker. The concurrent increase in the 3114 cm−1 peak confirms the presence of a CFCH double bond. The solvent-soluble portions and bulk specimens have very similar infrared features. © 1996 John Wiley & Sons, Inc.

5518633 Process for treating aqueous media containing metal ions: Brown Cary; Craven John S; Martz Gregory A; Merkle James; Vick William L; Wagner Melissa, Waverly, United States assigned to E I Du Pont de Nemours and Company

Several fluorocarbon compounds have been evaluated as geothermal tracers in sand column tests using damp, dry, and untreated ‘washed sea sand’. Fluorocarbons evaluated in these tests included two hydrofluorocarbon freons: trifluoromethane (R23) and 1,1,1,2-tetrafluoroethane (R134a), and five perfluorocarbons: perfluorodimethylcyclobutane, perfluoromethylcyclopentane, perfluoromethylcyclohexane, perfluorodimethylcyclohexane and perfluorotrimethylcyclohexane. Transport of the fluorocarbon compounds was explored in flowing helium at 23 and 60 °C. This work found that fluorocarbon retention is strongly affected by sand moisture content. The fluorocarbon compounds flowed with the bulk fluid when the sand was damp, but were significantly retained by the solid phase when the sand was thoroughly dried. The data suggest that the fluorocarbons may be conservative tracers in geothermal conditions up to mild superheat but they may not be conservative at geothermal conditions with a high degree of superheat.

Fluorinated Amorphous Carbon Thin Films Grown from C4F8 for Multilevel Interconnections of Integrated Circuits

AbstractFluorinated amorphous carbon thin films (a-C:F) for use as low-dielectric-constant interlayer dielectrics were deposited by helicon-wave plasma-enhanced chemical vapor deposition using fluorocarbon compounds as a source material. The a-C:F films could be grown from C4F8 at a high deposition rate (above 400 nm/min) and they were thermally stable up to 300°C. The addition of bias power to the substrate made it possible to completely fill gaps in the wiring (space 0.35 μm, height 0.65 μm) with the a-C:F film. To protect the a-C:F film during further processing, we deposited a SiO2 film to add mechanical strength and resistance to the oxygen plasma used to remove resist materials. The adhesion between the a-C:F and SiO2 films was dramatically improved by inserting an adhesion promoter consisting of a-C:H and Si-rich SiO2.

Aggregation Behavior of Mixed Fluorocarbon and Hydrocarbon Molecules in Aqueous Organic Solvents. Nonideality and Ideality of Mixing

The emission spectra of naphthalene labeled hydrocarbons (NpHCn) and fluorocarbons (NpFCn) and anthracene labeled hydrocarbons (AnHCn) and fluorocarbons (AnFCn) in aqueous organic mixed solvents were investigated. The fluorescence spectrum of NpHC 16 in dimethyl sulfoxide-water (DMSO-H20) is dominated by excimer emission due to formation of aggregates. Addition of a fluorocarbon compound with chain length of seven perfluoromethylenes results in a reduction in the excimer emission and an enhancement of monomer emission, suggesting formation of coaggregates. In contrast, addition of a perfluorocarbon compound with chain length of 12 perfluoromethylenes results in no change in the fluorescence spectrum of NpHC16. Similarly, NpFC7 and NpFC12 in DMSO-H20 also exhibit excimer emission exclusively. Fluorescence studies show that hydrocarbon compounds coaggregate with NpFC7 but do not coaggregate with NpFC12. Selective excitation of the naphthalene moiety in the mixture solution of NpHC16 with AnFC7 or in the mixture solution of NpFC7 with AnHC12 exclusively leads to the emission of the anthracene moiety, suggesting that efficient energy transfer between the naphthalene and the anthracene chromophores occurs. On the other hand, for the mixture of NpHC16 with AnFC12 or NpFC12 with AnHC12, no energy transfer was detected. All these observations indicate that fluorocarbon compounds with short chains can mix with hydrocarbon compounds ideally, while those with long chains behave nonideally. The mixed critical aggregation concentrations of NpHC16 with NpFC7 and with NpFC12 are measured as a function of overall composition of the mixtures, which give insight into the magnitude of the nonideality of the mixings.

Hydrophobic effects on photochemical and photophysical processes: evidence for aggregation of perfluorocarbon in aqueous–organic solvents

The emission spectra and photodimerization of fluorinated alkyl 2-naphthoates (NpFCn) and 9-anthrylmethyl perfluoroalkanoates (AnFCn) in aqueous–organic binary solvents have been investigated. The fluorescence spectra of NpFCn in dimethyl sulfoxide–water mixture (DMSO–H2O) are dominated by excimer emission. Addition of long chain fluorocarbon compounds to the solution results in a reduction in the excimer emission and an enhancement of monomer emission. Selective excitation of the naphthalene moiety in the mixture solution of NpFCn and AnFCn leads to strong emission from AnFCn. Photoirradiation of NpFCn yields a ‘cubane-like’ photodimer with a relatively high quantum yield. All these observations suggest that hydrophobic interactions force molecules with long fluorocarbon chains to form aggregates in aqueous–organic binary solvents.