Copolymer Of Tetrafluoroethylene Research Articles

Surface functionalization of ethylene–tetrafluoroethylene copolymer film with poly(methyl methacrylate) via chemical radical polymerization

The surface of a poly(ethylene-co-tetrafluoroethylene) (ETFE) film was modified by grafting of methyl methacrylate (MMA) by using diethyl(1,10-phenanthroline N1,N10)zinc (Phen-DEZ) and oxygen molecules as the radical initiator. Fourier transform infrared (FT-IR) spectra and Raman spectra of polymethylmethacrylate-grafted-ETFE (ETFE-g-PMMA), showed absorption peaks attributed to carbonyl functionalities. And the thermal decomposition of ETFE-g-PMMA was observed in two stages. The first weight loss step was due to the disruption of the grafted PMMA polymer, while the second degradation step was likely due to thermal disruption of ETFE itself. These results provide clear evidence of PMMA grafting onto ETFE film. The grafting yield of MMA was found to be affected by the polymerization temperature, reaction time, and concentration of Phen-DEZ. Analysis of the surface morphology of the film by atomic force microscopy (AFM) suggests that MMA was grafted on the surface of the ETFE film. In addition, the water contact angle on the hydrophobic surface of the ETFE film changed from 94.6° to 65.5° depending on the graft of PMMA, resulting in hydrophilicity. Moreover, the results of the dyeing experiment showed that only the surface of the ETFE film was decorated with MMA and the interior was unchanged.

Free volume characteristics of 2,2‐bistrifluoromethyl‐4,5‐difluoro‐1,3‐dioxole‐co‐tetrafluoroethylene copolymers: Effect of composition and molecular weight

Abstract2,2‐bistrifluoromethyl‐4,5‐difluoro‐1,3‐dioxole‐co‐tetrafluoroethylene (PDD‐TFE) copolymer is a good candidate to prepare gas separation membranes with excellent permeability due to its free volume characteristics. However, the influence of PDD‐TFE copolymer structure on its free volume characteristics is less studied. In this paper, PDD‐TFE copolymers with different compositions and molecular weights were synthesized, and their free volume characteristics were analyzed by positron annihilation lifetime spectroscopy and a molecular dynamics simulation. It indicated that the molar fraction of PDD in copolymers had a significant effect on free volume characteristics, while the molecular weight of copolymers exerted a slight influence on free volume when the molecular weight exceeded a critical region (intrinsic viscosity [η] > 68 ml g−1). PDD‐TFE copolymers with greater PDD molar fractions (i.e., 72% and 84%) showed bimodal distributions in positron lifetime and free volume size distributions, while PDD‐TFE copolymers with lower PDD molar fractions (i.e., 27% and 35%) exhibited a single peak. The long‐lifetime parameter τ3 was assigned to micro‐cavities formed by [‐(TFE)y‐PDD‐] segments and τ4 was attributed to micro‐cavities formed by [‐(PDD)x‐TFE‐] segments. The cis and trans transitions of PDD led to a local multilayer spiral structure with a 2.6–4.3 Å layer spacing, which would also increase the free volume of copolymers.

Scattering Properties of an Optical Fiber with a Silica Light-Conducting Core and a Light-Reflecting Shell Fabricated from a Fluorinated Thermoplastic Polymer

The scattering properties of an optical fiber with a silica light-conducting core and a light-reflecting shell made of a fluorinated thermoplastic copolymer of tetrafluoroethylene with Tefzel ethylene have been experimentally studied. It is established that when radiation (λ = 532 nm) propagates along this fiber, a noticeable scattering of the evanescent part of the wave propagating along the reflective shell is observed. The shell scattering indicatrix, the distribution of the scattered radiation intensity along the fiber axis, and its dependence on the conditions of radiation input into the optical fiber were measured. The total scattered radiation is calculated and compared with the radiation transmitted through an optical fiber. The possibility of using these optical fibers in laser medicine is discussed.

The Analysis of Light Intensity Transmission Coefficient Through Plastic Fibers for the Design of Closed Room Lighting without Electricity

The phenomenon of total internal reflection can be used to guide the light to be transmitted from one place to another, it is applied to the guiding principle of light in fiber optics. A fiber rope made of clear plastic material with a uniform refractive index, when one end fired a beam of light then the light will be forwarded along the strap so that out at the other end. This principle can be applied as a lighting source in a closed room by passing light from the outdoors by using plastic fiber, so it doesn’t need the electricity. In this study, theoretical analysis of the percentage of the intensity of light transmitted by the fiber plastic succeed as a function of the refractive index and determine the transmission coefficient for some plastic seeds are eligible to be used as a plastic fiber light successor. From the results of deriving the equation, the light transmission coefficient of plastic is and the terms of plastic seeds that can be used as a plastic fiber are having a refractive index . Based on refractive index data from profesionalplastics, the maximum transmission coefficient value for Ethylene Tetrafluoro Ethylene Copolymer is 82.23% and the minimum transmission value of Fluorinated Ethylene Propylene Copolymer is 55.99%.

Perfluorodioxolane Polymers for Gas Separation Membrane Applications.

Since the discovery of polytetrafluoroethylene (PTFE) in 1938, fluorinated polymers have drawn attention in the chemical and pharmaceutical field, as well as in optical and microelectronics applications. The reasons for this attention are their high thermal and oxidative stability, excellent chemical resistance, superior electrical insulating ability, and optical transmission properties. Despite their unprecedented combination of desirable attributes, PTFE and copolymers of tetrafluoroethylene (TFE) with hexafluoropropylene and perfluoropropylvinylether are crystalline and exhibit poor solubility in solvents, which makes their processability very challenging. Since the 1980s, several classes of solvent-soluble amorphous perfluorinated polymers showing even better optical and gas transport properties were developed and commercialized. Amorphous perfluoropolymers exhibit, however, moderate selectivity in gas and liquid separations. Recently, we have synthesized various new perfluorodioxolane polymers which are amorphous, soluble, chemically and thermally stable, while exhibiting much enhanced selectivity. In this article, we review state-of-the-art and recent progress in these perfluorodioxolane polymers for gas separation membrane applications.

Proteolytically Degraded Alginate Hydrogels and Hydrophobic Microbioreactors for Porcine Oocyte Encapsulation.

In reproductive biology, the biotechnology revolution that began with artificial insemination and embryo transfer technology led to the development of assisted reproduction techniques such as oocyte in vitro maturation (IVM), in vitro fertilization (IVF) and cloning of domestic animals by nuclear transfer from somatic cell. IVM is the method particularly of significance. It is the platform technology for the supply of mature, good quality oocytes for applications such as reduction of the generation interval in commercially important or endangered species, research concerning in vitro human reproduction, and production of transgenic animals for cell therapies. The term oocyte quality includes its competence to complete maturation, be fertilized, thereby resulting in healthy offspring. This means that oocytes of good quality are paramount for successful fertilization including IVF procedures. This poses many difficulties to develop a reliable culture method that would support growth not only of human oocytes but also of other large mammalian species. The first step in IVM is the in vitro culture of oocytes. This work describes two protocols for the 3D culture of porcine oocytes. In the first, 3D model cumulus-oocyte complexes (COCs) are encapsulated in a fibrin-alginate bead interpenetrating network, in which a mixture of fibrin and alginate are gelled simultaneously. In the second one, COCs are suspended in a drop of medium and encapsulated with fluorinated ethylene propylene (FEP; a copolymer of hexafluoropropylene and tetrafluoroethylene) powder particles to form microbioreactors defined as Liquid Marbles (LM). Both 3D systems maintain the gaseous in vitro culture environment. They also maintain COCs 3D organization by preventing their flattening and consequent disruption of gap junctions, thereby preserving the functional relationship between the oocyte, and surrounding follicular cells.

THE INVESTIGATION ON THERMAL OXIDATIVE DESTRUCTION AND ASSESSMENT OF RUBBER SERVICE PERIOD BASED ON TRIPLE COPOLYMER OF TETRAFLUOROETHYLENE, VINYLIDENE FLUORIDE AND HEXAFLUOROPROPYLENE

By thermogravimetric analysis it was studied the thermal oxidative degradation of rubber based on a triple copolymer of tetrafluoroethylene, vinylidene fluoride, and hexafluoropropylene. It was found that the object is characterized by a sufficiently high heat resistance, which is proven by the rather high temperature of loss of 5% of the initial mass of the sample (412 ° C). The service life of the tested unloaded material in air atmosphere, according to the Arrhenius equation, is 2084, 450 and 107 days at the temperature of 185, 200 and 215 ° C respectively.

The synergistic effect of fluorosilicone and silica towards the compatibilization of silicone rubber and fluoroelastomer based high performance blend

Fluoroelastomer and silicone rubber lie in the two different poles of elastomer family in terms of polarity. Hence, combining them in a single material and making it as at least technologically compatible substance is a great challenge. In this article, the compatibilization effect of fluorosilicone rubber (block copolymer) (trifluoropropylpolydimethylsiloxane) with various loading of modified silica filler on the novel advanced polymer architecture based fluoroelastomer (copolymer of hexafluoropropylene, vinylidene fluoride, and tetrafluoroethylene) and silicone rubber (poly methylvinylsiloxane) blends has been studied in details. The mechanical properties show significant improvement at room temperature (13%) and remarkably more at high temperature (54%) for the compatibilized system. Tan delta peak shifting in DMA study indicates better compatibilization for 2.5 phr loading of fluorosilicone and 15 phr loading of silica at 50/50 blend ratio. The reduction in domain size (from ⁓3 μm to ⁓200 nm) of the fluorocarbon phase by the synergistic effect of silica and fluorosilicone proves the decrease in interfacial tension and better compatibilization. This blend can be judiciously applicable in the sealing system as oil and fuel resistant O-rings and gaskets for a very wide range of temperature.

Surface Engineering of Organic Polymers by Photo‐induced Free Radical Coupling with p‐Dimethylaminophenyl Group as A Synthesis Block

AbstractThis contribution presents a versatile strategy to transfer unactivated surface C–H bonds of polymeric substrates to C–R–F groups (R stands for a spacer and F stands for functional group) by UV light‐assisted surface free radical coupling. With p‐dimethylaminophenyl radical as a building block, various reactive groups, such as –CHO, –SH, –B(O)OH, –CN and –SO3−, are successfully grafted onto typical commercial polymer substrates including biaxially oriented polypropylene, polyethylene phthalate, ethylene tetrafluoroethylene copolymer and dimethyl silicone rubber. Fluorencence microscope images, X‐ray photoelectron spectroscopy, UV‐vis and fluorescence spectra support that the above functional groups are covalently bonded to the polymer substrates. The concentration of the reactive groups immobilized on the different substrates is in the order of 10−8 to 10−7 mmol mm−2 determined by UV‐vis spectrometry. In addition, as a proof‐of‐concept, the introduced functional groups are demonstrated by their special reactions, for example, –CHO reacting with –NH2 to synthesize Schiff base, –SH to detect silver ions, and the complexes of –C=N and Zn2+ to degrade Rhodamine B. The results indicate that one can fabricate an integrated molecular library on the surface of polymeric substrates at the molecular level by selecting the building blocks.

Fabrication and Optical Modeling of Micro‐Porous Membranes Index‐Matched with Water for On‐Line Sensing Applications

AbstractMembranes made of perfluorinated materials having a refractive index close to that of water enable straightforward detection of water solutes at the interface, hence providing a novel sensing tool for fluidic systems. Here it is reported the production by non‐solvent induced phase separation and characterization of microporous membranes made of Hyflon AD, an amorphous copolymer of tetrafluoroethylene. Their optical turbidity when soaked in liquids having different refractive indices is studied and the data are interpreted with an optical model linking scattered light and structural features of the membrane. The average polymer and pore chord lengths obtained in this way scale with the filtering pore size measured by capillary flow porometry. Then, the optical response of the membranes when soaked in aqueous surfactant solutions is investigated and the effects of the molecular adsorption on the internal membrane surface is successfully interpreted by an extension of the model. Overall, the results show that index‐matched membranes can be designed and produced to provide a simple optical detection of the composition of the soaking liquid or to monitor the initial stage of membrane fouling.

Composition Polymeric Membranes Based on the VDF-TeFE Copolymer Formed by Electrospinning

The paper presents the results of pilot studies on the formation of non-woven hydrophilic piezoelectric composite polymer membranes based on a copolymer of vinylidene fluoride and tetrafluoroethylene (VDF-TeFE) and polyethenylpyrrolidine (PEP) by electrospinning. Using optical goniometry, the effect of the PEP content on the wetting of the membrane surface with water was established. Using scanning electron microscopy, the influence of the content PEP on the structure of the formed membranes was studied. The effect of an isotonic NaCl solution on the structure of the formed membranes upon their dissolution within 7 days was studied. Based on studies of the chemical composition of the membranes before and after their dissolution, an assumption was made about the possibility of using the developed membranes for targeted delivery of pharmacological preparations for wound healing.

Исследование высокотемпературного предела текучести армированного углерод-ными волокнами сополимера тетрафторэтилена с гексафторпропиленом

Исследование высокотемпературного предела текучести армированного углерод-ными волокнами сополимера тетрафторэтилена с гексафторпропиленом

A Study of the Optical Properties of a Multimode Silica Optical Fiber with a Reflective Shell from a Fluorinated Thermoplastic Polymer

The optical properties of a silica–polymer optical fiber with a light-guide core with a diameter of 430 μm and a reflecting shell with a thickness of 70 μm from a thermoplastic copolymer of tetrafluoroethylene with ethylene of Tefzel brand have been experimentally studied. The polymer coating is applied to a silica fiber directly in the fiber draw apparatus by the die method from a thermoplastic melt. The optical losses of the drawn fiber and the numerical aperture and its dependence on the fiber length are measured. It is established that a light propagating through the fiber is noticeably scattered by the reflecting shell, which is associated with the crystallinity of the polymer. The distribution of the scattered radiation intensity along the fiber axis and the indicatrix of radiation scattering by the shell are measured. The relative contributions of scattering and absorption of light in the shell to the total optical losses of the fiber are estimated. The possible use of optical fibers of this structure in laser medicine is considered.

Multicore large-aperture fiber-optic probe based on quartz–quartz-type lightguides for near-infrared fluorimeters

The optimization problem of the parameters of lightguides for fiber-optic probes used in fluorescent tumor diagnostics (of benign and malignant tumors) is considered. It has been shown that, to increase the sensitivity of a fluorimeter in the near-infrared region, it is promising to use fiber lightguides of the quartz–quartz type, with an increased numerical aperture of up to 0.30 and a biocompatible protective coating of P-12 polyamide or tetrafluoroethylene copolymer with Tefzel ethylene, as probe lightguides for detecting luminescence. Using such lightguides, a prototype version of a 19-core large-aperture fiber-optic probe for a laser oncofluorometer with increased sensitivity operating in the spectral range 900–1100 nm has been developed. The minimum dose of the injected drug was 10 μg/kg of bio-object weight, which corresponds to a world-class level of sensitivity of photosensitizer detection in biological tissues.

Structural, optical, and electrical properties of ferroelectric copolymer of vinylidenefluoride doped with Rhodamine 6G dye

An effect of Rhodamine 6G dye introduced into vinylidenefluoride and tetrafluoroethylene copolymer on a number of its structural and electrical characteristics has been detected. It was shown that at film crystallization, the inserted dopant shifts the equilibrium distribution of isomers to the side of increasing concentrations of chains with the conformation of a planar zigzag. The dye introduced strongly increases ac conductivity, especially at high electric fields. The investigation of high voltage polarization under bipolar external field conditions shows slow switching of gigantic current which is observed at fields lower than coercive ones. The estimation of the charge density indicates the non-ferroelectric nature of the phenomenon observed. The analysis of the data shows that in the system, Maxwell–Wagner relaxation processes take place, which lead to the space charge formation in the polymer matrix. It is established that current switching observed must be attributed to the relaxation of the space charge field.

Polytetrafluoroethylene: Synthesis and Characterization of the Original Extreme Polymer.

This Review aims to be a comprehensive, authoritative, and critical review of general interest to the chemistry community (both academia and industry) as it contains an extensive overview of all published data on the homopolymerization of tetrafluoroethylene (TFE), detailing the TFE homopolymerization process and the resulting chemical and physical properties. Several reviews and encyclopedia chapters on the properties and applications of fluoropolymers in general have been published, including various reviews that extensively report copolymers of TFE (listed below). Despite this, a thorough review of the specific methods of synthesis of the homopolymer, and the relationships between synthesis conditions and the physicochemical properties of the material prepared, has not been available. This Review intends to fill that gap. As known, PTFE and its marginally modified derivatives comprise some 60-65% of the total international fluoropolymer market with a global increase of ca. 7% per annum of its production. Numerous companies, such as Asahi Glass, Solvay Specialty Polymers, Daikin, DuPont/Chemours, Juhua, 3F, 3M/Dyneon, etc., produce TFE homopolymers. Such polymers, both high-molecular-mass materials and waxes, are chemically inert and hydrophobic and exhibit an excellent thermal stability as well as an exceptionally low coefficient of friction. These polymers find use in applications ranging from coatings and lubrication to pyrotechnics, and an extensive industry (electronic, aerospace, wires and cables, and textiles) has been built around them. South Africa, being the third largest producer of fluorspar (CaF2), the precursor to hydrogen fluoride and fluorine, has embarked on an industrial initiative to locally beneficiate its fluorspar reserves, with the local production of fluoropolymers being one projected outcome. As our manuscript focuses specifically on the homopolymerization of TFE (the starting point for all fluoropolymer industries), it will be of considerable use to start-up companies and other commercial entities looking to enter the fluoropolymer market, as well as to end-user companies. The manuscript commences with a short discussion on the synthesis and production of TFE (both at industrial and laboratory scales), including the safety aspects surrounding handling (because that monomer is regarded as explosive if brought into contact with oxygen due to the formation of peroxides), transport, and storage, and then expands into detailed discussions dealing with aspects such as the various additives used (buffers, chain transfer agents, surfactants, etc.), the solvent environment, and the reaction conditions. A further section reports the properties of PTFE with respect to the polymerization conditions as well as an overview on the specialized techniques used to characterize PTFE. Finally, the applications of PTFE in various fields, ranging from electrical insulation to tribological to medical applications, as well as chemically resistant coatings and pyrotechnics, are discussed.

Luminescent Composites Based on Tetrafluoroethylene Copolymer Porous Films Produced by the Diffusion Embedding of Semiconductor Nanoparticles in a Supercritical Medium

A method for creating film composites based on a new material—a fibrous copolymer of tetrafluoroethylene and vinylidene fluoride—using the diffusion embedding of ready-made nanoparticles into a porous matrix in a supercritical (SC) carbon dioxide medium is developed. The method of cold or hot pressing of impregnated porous films was used at the final stage of creation of such composites. The peculiarities of the effect of the supercritical fluid treatment of porous copolymer films on the surface structure of pressed films are discussed. Luminescent composites with semiconductor nanoparticles of cadmium selenide and nanocrystalline silicon are obtained; their radiation covers a range of 500–1000 nm. The change in the luminescence properties of the resulting nanocomposites under the action of excitation laser radiation at 405 nm is demonstrated.

Fabrication and properties of FEP fibers by melt spinning method

ABSTRACTPoly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) is a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) which not only maintains the excellent properties of polytetrafluoroethylene (PTFE) but also breaks the drawback of PTFE's hard melt-processability. In this study, FEP fibers were spun by melt spinning method using a single screw extruder. The obtained FEP fibers’ thermal and crystallization properties were investigated via DSC, XRD and DMA respectively. Results showed that FEP fibers’ melting temperature and crystallinity degree improved as the heat setting temperatures rising from 120℃ to 160℃. The melting enthalpy increased from 29.3 J/g to 31.5 J/g while the crystal temperature decreased from 233.8℃ to 232.1℃. The morphologies of FEP fiber showed that the grooves became light, and accompanied with the decrease of the fiber diameter when the nascent fiber suffered drawing.

Influence of Gamma-Irradiation and Thermal Annealing on Molecular–Topological Structure of Tetrafluoroethylene–Ethylene Copolymer

The molecular–topological structure of a tetrafluoroethylene copolymer with ethylene after γ-irradiation and thermal annealing has been studied. The pseudo-network structure of the copolymer contains, in addition to the amorphous block, crystalline segments of macromolecules in the role of branching sites. Topologically, the diblock structure of the copolymer after thermal annealing at 538 K is transformed into a three-block structure with the appearance of a high-temperature amorphous block. Irradiation of the copolymer with γ-rays to a dose of 150 kGy does not lead to appreciable changes in its molecular–topological structure.

An effect of the film texture on high-voltage polarization and local piezoelectric properties of the ferroelectric copolymer of vinylidene fluoride

Vinylidene fluoride and tetrafluoroethylene copolymer 94/6 texturing has been carried out by one-axis drawing at Td = 75 °C up to the ratio of 6 with subsequent isometric tempering at 130 °C. Data of X-ray diffraction and IR-spectroscopy indicate partial polymorph transition from the metastable γ-phase to the polar β-modification with long segments in the conformation of the planar zigzag. The surface topography data show that the oriented film roughness turns out to be almost three times lower than that of the isotropic one. High-resolution vector piezoresponse force microscopy (PFM) has been used to investigate topography and ferroelectric domains in polymer films for visualization out-of-plane and in-plane polarization components. It is shown that, in the oriented sample, both crystallinity and the degree of polar β-phase crystal perfection are higher. It was found that conductivity “abnormal” dropping takes place at the stage of intensive Pr rising with the field growing. This fact is explained by quick trapping of charge carriers by polar planes of crystals with increasing the effective trap area.