Fluorine Polymers Research Articles

Synthesis, Characterization, and Environmental Applications of Novel Per-Fluorinated Organic Polymers with Azo- and Azomethine-Based Linkers via Nucleophilic Aromatic Substitution.

This study reports on the synthesis and characterization of novel perfluorinated organic polymers with azo- and azomethine-based linkers using nucleophilic aromatic substitution. The polymers were synthesized via the incorporation of decafluorobiphenyl and hexafluorobenzene linkers with diphenols in the basic medium. The variation in the linkers allowed the synthesis of polymers with different fluorine and nitrogen contents. The rich fluorine polymers were slightly soluble in THF and have shown molecular weights ranging from 4886 to 11,948 g/mol. All polymers exhibit thermal stability in the range of 350-500 °C, which can be attributed to their structural geometry, elemental contents, branching, and cross-linking. For instance, the cross-linked polymers with high nitrogen content, DAB-Z-1h and DAB-Z-1O, are more stable than azomethine-based polymers. The cross-linking was characterized by porosity measurements. The azo-based polymer exhibited the highest surface area of 770 m2/g with a pore volume of 0.35 cm3/g, while the open-chain azomethine-based polymer revealed the lowest surface area of 285 m2/g with a pore volume of 0.0872 cm3/g. Porous structures with varied hydrophobicities were investigated as adsorbents for separating water-benzene and water-phenol mixtures and selectively binding methane/carbon dioxide gases from the air. The most hydrophobic polymers containing the decafluorbiphenyl linker were suitable for benzene separation, while the best methane uptake values were 6.14 and 3.46 mg/g for DAB-Z-1O and DAB-A-1O, respectively. On the other hand, DAB-Z-1h, with the highest surface area and being rich in nitrogen sites, has recorded the highest CO2 uptake at 298 K (17.25 mg/g).

Proton Polymer Electrolytes in Fuel Cell

The electrolyte is one of the main parts of a fuel cell. That is divided into liquid and solid and it is used in both Alkaline and acidulous PH. But with due to kind of electrolyte was used in it, it divides to these parts: 1) Polymeric fuel cell or proton changing. 2) Alkaline fuel cell. 3) Acid phosphoric fuel cell. 4) Melted carbon fuel cell. 5) Solid oxide fuel cell. Only free positive ions move for transfer positive stress through the membrane:For this reason, it is called a reformer membrane. Through the work of fuel cell. Electrolyte must be wet so it's conductance remain. So with attendance to the pressure used in fuel cells, for prevention of steam, the temperature must be kept between 70- 120˚c.In atmosphere pressure, the revenue temp must be lower than 100˚c. It is better to be between 60 to 70˚c. Until remain the quantity of water in the normal case(position). the water transfers in two way at polymeric electrolyte. One is electrical osmotic flow which transfers water and proton from anode to cathode. Another kind of transfer is, the influence of water reversed. (Diffusion flux).It means water will come back from the cathode to the anode. So a balance of water in polymeric electrode deepens on how flowing electrical osmotic and influence of reverse water. The compositions in the polymeric membrane: The electrolyte be used in this kinds of cells (proton polymer) is a solid membrane made of an organic substance that can change Ions. It made from sulfonic acid polymer impregnated with Fluorine or similar polymers. Among them (perfluoro carbon sulfonic acid) that is sedimented on webbed condition (situation). Fluorocarbon polymers are usually expensive and made of them need to special technology. One way to make these kinds of polymers is: fluorocarbon polymer must be extruded to thermoplastic fluoride sulfonyl. To keep properties of substances through the process materials should be in normal conditions. Polymeric electrolytes area different, but in most cases, they use from nafionTM. The thickness of the membrane made of NafionTM is 50 - 175micron. The structure of NafionTM comparatively is hard and permanent and it made from (3) three parts, three main part. 1)Teflon: like carbon-fluorine that have hundred unit of __CF2__CF__CF2__ connected to each other linear. 2) Transversal pat of chain __O__CF2__CF1__O__CF2__ that connects Teflon part to third polymer part. 3) Cluster Ions that consist of sulfuric acid Ions (SO3 -H+). Particulars of polymer membrane: one particular need to the membrane is the thinness of the membrane, when the membrane became thicker, the capacity of the cell be lowed (to be decreased).But thickness lower than 0.1 mm is good.The low resistance of membrane makes the increase of proton transfer capacity. We can use another polymer as membrane like polystyrene sulfonate. But this kind of materials has not (don’t have) suitable chemical resistance for a long time. Among suitable properties of proton interchange membrane, is lack of it sensitive during current and resistance connect or disconnect against separation (change to deference layer). Since low act temperature in these cells, it used from the catalyst in their structure. The best catalyst is platinum and another precious metal, which is deposited a little on the porous carbon.The porosity on electrode makes it easier to diffusion of reactants. For best hydrophobic polymer.platinum particles were deposited on a very thin carbon and they have a diameter about 2 nanometers and prepare spread effect surface for gas reactions. It is mentionable that use of Nanotechnology especially Carbon Nanotubes with direction and certain structure is one of basic forms in properties welfare of this materials in porous membranes for use. Nanopipes, Fueling and similar structures are more suitable for keeping hydrogen and hydrocarbons, to these cells expenses. Also, carbon structures (Nanomaterials-Graphite Nanofibre and Carbonic Nanotubes) are making a Hydrogen potentiality as fuel, they can increase the efficiency of these cells and be economical more and more. Of course in this essay, we explain in detail the way of providing skilled (efficient) polymeric membrane and less expense. After that, we study its problems.Polymeric Electrolyte and Polymeric Membrane with a property of proton interchange: 1) Compositions used in the polymeric membrane. 2) Properties of the polymeric membrane. 3) Way to prepare the polymeric membrane in lab scale. 4) Keeping the humid of the polymeric membrane. 5) Polymeric fuel cell with Catalyst Exothermic system in cold weather. 6) Make of membrane _electrode fuel cell. 7) The way of making membrane electrode cell in lab scale. Figure 1

Development of highly durable deep-ultraviolet AlGaN-based LED multichip array with hemispherical encapsulated structures using a selected resin through a detailed feasibility study

To replace mercury lamps with AlGaN-based deep-ultraviolet (DUV) LEDs, a simple and low-cost package with increased light extraction efficiency (LEE) is indispensable. Therefore, resin encapsulation is considered to be a key technology. However, the photochemical reactions induced by DUV light cause serious problems, and conventional resins cannot be used. In the former part of this study, a comparison of a silicone resin and fluorine polymers was carried out in terms of their suitability for encapsulation, and we concluded that only one of the fluorine polymers can be used for encapsulation. In the latter part, the endurance of encapsulation using the selected fluorine polymer was investigated, and we confirmed that the selected fluorine polymer can guarantee a lifetime of over 6,000 h at a wavelength of 265 nm. Furthermore, a 3 × 4 array module of encapsulated dies on a simple AlN submount was fabricated, demonstrating the possibility of W/cm2-class lighting.

Star Polymer Gels with Fluorinated Microgels via Star-Star Coupling and Cross-Linking for Water Purification.

Two types of star polymer gels containing perfluorinated microgels were created as purification materials to separate polyfluorinated surfactants (e.g., perfluorooctanoic acid) from water. One macrogel is prepared by the radical coupling of fluorine and/or amine-functionalized microgel star polymers alone, while another is done by the radical cross-linking of the star polymers with poly(ethylene glycol) methyl ether methacrylate. Importantly, the reactive olefin remaining within the microgel cores was directly employed for both coupling and cross-linking reactions. Swelling properties of star polymer gels were effectively controlled by the latter cross-linking technique. Analyzed by small-angle X-ray scattering, a star-star coupling gel typically consists of a three-dimensional network where star polymers are sequentially connected with the microgels at the constant interval of about 20 nm. Owing to the fluorous and acid/base cooperative interaction, star polymer gels carrying fluorine/amine-functionalized microgels efficiently captured polyfluorinated surfactants in water and successfully afforded the removal from water via simple mixing and filtration.

A comparative study of charge transport in quasi-solid state dye-sensitized solar cells using polymer or nanocomposite gel electrolytes

To improve the photovoltaic and durability performance of quasi-solid dye-sensitized solar cells (DSCs), we added selected gelators to the liquid electrolyte. Metal-oxide nanoparticles or fluorine polymers were employed to solidify 3-methoxypropionitrile-based liquid electrolytes containing an ionic liquid, 1,2-dimethyl-3-propyl imidazolium iodide, as a source of iodide. The electrochemical impedance spectroscopy and cyclic voltammetry were employed to study the kinetics of electrochemical and photoelectrochemical processes, including the elucidation of the electronic and ionic processes occurring in the various quasi-solid-state solar cells. Among tested gelators, a cell with TiO2 solidified electrolyte (P25, 17.5wt%) exhibited the best photovoltaic performance with power conversion efficiency 7.65% under simulated sunlight (100mWcm−2). The DSCs with a TiO2 solidified electrolyte showed endurance of stability superior to that of a pure liquid electrolyte.

Plasma chemical behaviour of reactants and reaction products during inductively coupled CF4 plasma etching of SiO2

A two-dimensional fluid model has been developed to study plasma chemical behaviour of etch products as well as reactants during inductively coupled CF4 plasma etching of SiO2. The plasma fluid model consisted of Maxwell's equations, continuity equations for neutral and charged species including gas-phase and surface reactions and an energy balance equation for electrons. The surface reaction model assumed Langmuir adsorption kinetics with the coverage of fluorine atoms, fluorocarbon radicals and polymers on SiO2 surfaces. Numerical results indicated that etch product species occupy a significant fraction of reactive ions as well as neutrals in the reactor chamber during etching, which in turn leads to a change in plasma and surface chemistry underlying the processing. In practice, the density of SiF4 was typically about 10% of that of the feedstock CF4, being comparable to that of the most abundant fluorocarbon radical CF2; moreover, the density of was typically about 5% of that of the most abundant fluorocarbon ion . The density and the distribution of such product species in the reactor chamber were changed by varying the ion bombardment energy on the substrate surfaces, gas pressure, mass flow rate and coil configuration, which arises in part from gas-phase reactions depending on plasma electron density and temperature. Surface reactions on the chamber walls and on the substrate also affect the product density and distribution in the reactor; in particular, the surface reactions on the SiO2 dielectric window as well as substrate surfaces were found to largely affect the product density and distribution.

Molecular dynamics simulations of RDX and RDX-based plastic-bonded explosives

Molecular dynamics simulations have been performed to investigate well-known energetic material cyclotrimethylene trinitramine (RDX) crystal and RDX-based plastic-bonded explosives (PBXs) with four typical fluorine-polymers, polyvinylidenedifluoride (PVDF), polychlorotri-fluoroethylene (PCTFE), fluorine rubber (F 2311), and fluorine resin (F 2314). The elastic coefficients, mechanical properties, binding energies, and detonation performances are obtained for the RDX crystal and RDX-based PBXs. The results indicate that the mechanical properties of RDX can be effectively improved by blending with a small amount of fluorine polymers and the overall effect of fluorine polymers on the mechanical properties of the PBXs along three crystalline surfaces is (0 0 1) > (0 1 0) ≈ (1 0 0) and PVDF is regarded to best improve the mechanical properties of the PBXs on three surfaces. The order of the improvement in the ductibility made by the fluorine polymers on different surfaces is (0 0 1) ≈ (0 1 0) > (1 0 0). The average binding energies between different RDX crystalline surfaces and different polymer binders are obtained, and the sequence of the binding energies of the PBXs with the four fluorine polymers on the three different surfaces is varied. Among the polymer binders, PVDF is considered as best one for RDX-based PBXs. The detonation performances of the PBXs decrease in comparison with the pure crystal but are superior to those of TNT.

Molecular dynamics study of binding energies, mechanical properties, and detonation performances of bicyclo-HMX-based PBXs

To investigate the effect of polymer binders on the monoexplosive, molecular dynamics simulations were performed to study the binding energies, mechanical properties, and detonation performances of the bicyclo-HMX-based polymer-bonded explosives (PBXs). The results show that the binding energies on different crystalline surfaces of bicyclo-HMX decrease in the order of (0 1 0) > (1 0 0) > (0 0 1). On each crystalline surface, binding properties of different polymers with the same chain segment are different from each other, while those of the polymers in the same content decrease in the sequence of PVDF > F 2311 > F 2314 ≈ PCTFE. The mechanical properties of a dozen of model systems (elastic coefficients, various moduli, Cauchy pressure, and Poisson's ratio) have been obtained. It is found that mechanical properties are effectively improved by adding small amounts of fluorine polymers, and the overall effect of fluorine polymers on three crystalline surfaces of bicyclo-HMX changes in the order of (0 1 0) > (0 0 1) ≈ (1 0 0). In comparison with the base explosive, detonation performances of the PBXs decrease slightly, but they are still superior to TNT. These suggestions may be useful for the formulation design of bicyclo-HMX-based PBXs.

Thin films with chemically graded functionality based on fluorine polymers and stainless steel

Thin films of stainless steel and poly(tetrafluoroethylene) were co-deposited, by radiofrequency magnetron sputtering, in an inert atmosphere in order to produce a functionally graded material as a coating on a traditional biomaterial, where non-ferromagnetic characteristics and improved wettability must be ensured. These thin films are intended to modify the surface of SS316L used in stents, where the bulk/thin film couple should be regarded as a single material. This requires excellent adhesion of the coating to the substrate. All coatings were deposited with an average thickness of 500 nm. The chemical and phase characterization of the surface revealed that, with the increase in F content, the thin film evolves from a ferritic phase (α) to an amorphous phase with dispersion of a new crystalline ceramic phase (FeF 2). For intermediate F content values, an austenitic (1 1 1) phase (γ) was present. Bearing in mind the envisaged application, the best results were attained for thin films with a fluorine content between 10 and 20 at.%.

Development of Synchrotron DSC/WAXD/SAXS Simultaneous Measurement System for Polymeric Materials at the BL40B2 in SPring-8 and its Application to the Study of Crystal Phase Transitions of Fluorine Polymers

A new system of rapidly-scanning DSC/WAXD/SAXS simultaneous measurements has been successfully developed at the BL40B2 in SPring-8, Japan. The combination of the ultra-bright and highly-directional X-ray beams with the highly-sensitive two-dimensional (2D) detectors such as an imaging plate (IP), a CCD detector and a flat panel (FP) detector has made it possible to perform the rapidly-scanning time-resolved measurements of WAXD and SAXS for the polymeric materials subjected to the various kinds of external field like temperature, tensile force, magnetic field, hydrostatic pressure, and so on. The experimental data about the phase transitions of vinylidene fluoride-trifluoroethylene copolymer with VDF 82 mol % content and poly(vinylidene fluoride) form I have been presented as actual examples, where the phase transitions of the polar crystal consisting of planar-zigzag chains to the gauche-type high-temperature phase have been confirmed definitely and the remarkable change in lamellar stacking structure could be detected in the temperature region immediately below the melting point.

Molecular Dynamics Simulations of trans-1,4,5,8-Tetranitro-1,4,5,8-tetraazadecalin-Based Polymer-Bonded Explosives

Molecular dynamics has been applied to investigate the low-sensitivity explosive TNAD (trans-1,4,5,8-tetranitro-1,4,5,8-tetraazadecalin)-based polymer-bonded explosives (PBXs) with four typical fluorine polymers, PVDF (polyvinylidenedifluoride), PCTFE (polychlorotrifluoroethylene), F(2311) (fluorine rubber), and F(2314) (fluorine resin). The elastic constants, mechanical properties (tensile modulus, bulk modulus, shear modulus, and Poission ratio), binding energies, and detonation performances are first reported for the TNAD-based PBXs. The results show that the mechanical properties of TNAD can be effectively improved by the addition of small amounts of fluorine polymers, and the overall effect of fluorine polymers on the mechanical properties of the PBXs along three crystalline surfaces is (001) > (010) > (100). On each crystal surface, improvement in the ductibility made by the fluorine polymers changes approximately in the sequence of PVDF > F(2311) > F(2314) > PCTFE. The binding energies between different TNAD crystalline surfaces and different polymer binders with the same chain segment or mass fraction both decrease in the order of (010) > (100) > (001). The binding properties of the polymers with the same chain segment on each crystal surface of TNAD increase as PVDF < F(2311) < F(2314) < PCTFE, while those of different polymers in the same content decrease in the sequence of PVDF > F(2311) > F(2314) > PCTFE. The detonation performances of the PBXs decrease in comparison with the pure crystal, but they are superior to those of TNT.

Molecular Dynamics Simulations for Pure ε-CL-20 and ε-CL-20-Based PBXs

Molecular dynamics has been employed to simulate the well-known high energy density compound epsilon-CL-20 (hexanitrohexaazaisowurtzitane) crystal and 12 epsilon-CL-20-based PBXs (polymer bonded explosives) with four kinds of typical fluorine polymers, i.e., polyvinylidenedifluoride, polychlorotrifluoroethylene, fluorine rubber (F(2311)), and fluorine resin (F(2314)) individually. The elastic coefficients, isotropic mechanical properties (tensile moduli, bulk moduli, shear moduli, and poission's ratios), and bonding energy are first reported for epsilon-CL-20 crystal and epsilon-CL-20-based polymer bonded explosives (PBXs). The mechanical properties of epsilon-CL-20 can be effectively improved by blending with a small amount of fluorine polymers, and the whole effect of the adding fluorine polymers to improve mechanical properties of PBXs along the three crystalline surfaces of epsilon-CL-20 is found to be (100) approximately (001) > (010). The interaction between each of the crystalline surfaces and each of the fluorine polymers is different, and the ordering of binding energy for the three surfaces is (001) > (100) > (010); F(2314) always has the strongest binding ability with the three different surfaces. F(2314) can best improve the ductibility and tenacity of PBX when it is positioned on epsilon-CL-20 (001) crystal surface. The calculations on detonation performances for pure epsilon-CL-20 crystal and the four epsilon-CL-20-based PBXs show that adding a small amount of fluorine polymer into pure epsilon-CL-20 will lower detonation performance, but each detonation parameter of the obtained PBXs is still excellent.

Preparation and Structure of Rhenium Fluoride Trioxide ReO3F, and the Polymorphism of Rhenium Trifluoride Dioxide, ReO2F3

AbstractThe methods of preparation of ReO3F are revised. ReO3F is an amorphous yellow solid that crystallizes into colorless needles after prolonged heating. Its structure is that of a fluorine and oxygen bridged chain with hexa coordinated rhenium atoms (a = 670.9(2), b = 596.6(2), c = 1030.6(4) pm, β = 90.057(7)°, space group P2/c. In presence of donor solvents ReO3F·2L (L = (C2H5)2O, (CH3)2O, THF) are formed. ReO2F3, if crystallized from HF, exists in two crystalline forms, both are fluorine bridged chain polymers. (ReO2F3‐I: a = 1539.7(3), b = 999.6(3), c = 924.4(2) pm, β = 95.25(1)°, space group P21/c; ReO2F3‐II: a = 544.9(1), b = 494.2(1), c = 1253.7(2) pm, β = 98.543(7)°, space group P21/c. ReO2F3 crystallizes from CFCl3 or SO2FCl as fluorine bridged cyclic trimer (a = 881.4(4), c = 822.1(6) pm, γ = 120°, space group P63/m, or fluorine bridged cyclic tetramer (a = 1107.8(2), b = 999.4(2), c = 1347.9(3) pm, space group Cmca).

Physical and chemical aspects of long-term biodeterioration of some polymers and composites.

A biodeterioration study was performed on synthetic polymeric materials including homogenous film made from poly(tetrafluorine ethylene), copolymer film made from tetrafluorine ethylene and perfluoromethyl vinyl ether, vulcanized rubber containing natural caoutchouc, and vulcanized rubber, the main component of which was synthetic butadiene nitrile caoutchouc. The materials were exposed for 12 years to the open air, in mycological containers, and in a cellar in maritime climate conditions: air humidity 72%-90% and seasonal average temperature of 17 degrees C in summer and -2.5 degrees C in winter. The studies of optical and electron microscopy revealed that microorganisms were able to develop not only on the surface of the materials but also to penetrate inside into deeper layers. The fungi that produced the most intensive deterioration in the fluorine polymers and vulcanized rubbers belonged to the Alternaria, Aspergillus, Aureobasidium, Cladosporium, Penicillium, Oidiodendron and Trichoderma genera. The fungi Aspergillus fumigatus, A. niger, Aureobasidium pullulans, and Trichoderma viride produced the most intensive deterioration in the fluorine films, whereas Alternaria tenuissima, Cladosporium herbarum, C. sphaerospermum, and fungi of the Oidiodendron genus were widespread on vulcanized rubbers. Fungi of the Aspergillus and Penicillium genera prevailed on both fluorine films and rubbers exposed in a cellar. Infrared spectroscopy indicated that the structures of poly(tetrafluorine ethylene) and the copolymer of tetrafluorine ethylene and perfluoromethyl vinyl ether did not change after the 12-year exposure; only insignificant changes in surface morphology were observed by optical microscopy. Vulcanized rubber made both from natural and from synthetic caoutchouc exposed for the same length of time showed rather evident changes in appearance and structure. X-ray graphical analysis revealed that new crystallization of the caoutchouc and a possible change in chemical composition of the fillers had occurred.

Solid-state 19F NMR investigation of poly(vinylidene fluoride) with high-power proton decoupling

The use of high-power proton decoupling has enabled highly-resolved spectra of fluorine polymers to be recorded, as is exemplified herein for semicrystalline poly(vinylidene fluoride) (PVDF). By means of high MAS speeds (up to 17 kHz), the spinning sidebands are removed from the whole of the relevant chemical shift range. For spectra of the crystalline regions of the polymer, the high-power decoupling is necessary, though its effect is not large. Various relaxation techniques have been used to examine the semicrystallinity and the polymorphism of PVDF, with special pulse sequences used to discriminate between the various domains. Different chemical shifts have been observed for the signals of the amorphous and crystalline phases. Those of the more immobile parts cover a substantial range.

Computer simulation of structure and ferroelectric phase transition of vinylidene fluoride copolymers (1) vdf content dependence of the crystal structure

Abstract Force field parameters of fluorine polymers have been refined so as to reproduce well the X-ray analyzed crystal structures and the observed IR/Raman spectra of various crystalline forms of poly (vinylidene fluoride) (PVDF). By using the thus established force field parameters, the crystal structure of the low-temperature phase of vinylidene fluoride-trifluoroethylene (VDF-TrFE) copolymers has been simulated. The VDF content dependence of the crystal structural parameters and the vibrational spectra could be reproduced reasonably by this computer simulation.

Research on New Energetic Materials

AbstractThe goal in this paper is to review progress in two emerging topics in energetic materials science. These emerging two areas are fluorine and oxygen rich energetic crystals and polymers and environmentally friendly energetic material classes.

Structural phase transition in ferroelectric fluorine polymers: X-ray diffraction and infrared/Raman spectroscopic study

Abstract The structural phase transition has been investigated by X-ray diffraction and infrared and Raman spectroscopic measurements for ferroelectric fluorine polymers, including poly(vinylidene fluoride) and its copolymers with trifluoroethylene or tetrafluoroethylene. One of the most characteristic features of this ferroelectric transition is the large conformational change of the molecular chains between the trans and gauche rotational isomers, quite different from the structural change observed generally in the usual ionic ferroelectric materials. The crystallization and transition behaviors depend sensitively on the monomer composition in the copolymers as well as on the sample preparation conditions. The roles of the optic and acoustic phonons in the ferroelectric phase transition have been discussed based on the temperature dependences of the far-infrared spectra and the ultrasonic velocity.

Surface Modification of Some Fluorine Polymer Films by Glow Discharges

Abstract Extensive study has been made of the effects of various types of glow discharge plasmas on the changes of the surface properties of some fluorine polymers. The properties were investigated as a function of such factors as the exposing period, aging after exposure, type of plasma, and so on. It was found that the wettability and the critical surface tensions were changed considerably with plasma exposure and that periods of several tens of seconds are long enough to cause changes. The extents of change were not so prominent for fluorine polymers as for polyethylene, and this fact may show the important role of the fluorine atom in the surface properties even after the plasma treatments.