Ever wonder what keeps the food from sticking to the non-stick cookware? Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene and is known by its common brand name Teflon. It is considered the most slippery solid ever made by humans. In addition to being a long-lasting material, it is a lubricant that does not evaporate like base oils, and thus, it enables the lubricant to last three to four times longer. These properties have made it familiar to many people as a coating on nonstick cookware. However, cookware was not the first application of Teflon. It was patented in 1941 by DuPont Company’s Jackson Laboratory as PTFE, a coating for the valves and seals of pipes containing highly radioactive uranium compounds during the Manhattan Project. It was until 1945 when a Frenchman, Marc Grégoire, came up with the idea of coating his fishing tackle with the compound, but it was actually his wife who had the brilliant idea of using it to coat pans. They subsequently went on to establish the brand Tefal. Due to its extreme heat and corrosive resistivity, Teflon is widely employed to almost every mechanism that is subjected to heat, wear, and friction, and in laboratory equipment that must resist corrosive chemicals. Teflon is so closely linked to our lives that it can be found in several items we come across every day.
Discovery
The discovery of Teflon was an accidental by-product of the search for better refrigerant during the late 1930s. In 1938, Roy J. Plunkett, an American chemist for E.I. du Pont de Nemours & Company (now DuPont Company), was researching new chlorofluorocarbons refrigerant as the previously existing refrigerants like sulfur dioxide and ammonia had become critical for human health. Plunkett had produced a hundred pounds of tetrafluoroethylene gas (TFE) and stored it in small cylinders at dry-ice temperatures before chlorinating it. When they prepared those cylinders for use, the gas stopped flowing while retaining the weight scale of the cylinder to similar reading. When they cut-open the cylinder, Plunkett found a white powder. He found the substance to be heat resistant and chemically inert, and to have very low surface friction so that most other substances would not adhere to it. Plunkett realized that TFE had polymerized into a substance with potentially useful characteristics which were unusual to the polymer science of that time.
Synthesis of Teflon
Teflon is prepared by the free-radical polymerisation of a monomer called tetrafluoroethylene (TFE). The polymerisation is a process in which relatively small molecules, known as monomers, are chemically combined to form a chain-like structure know as polymer. The polymerisation of Teflon is a two-step process. The first step is to prepare the raw material, TFE in this case, and the second, being the polymerisation of TFE itself. For the preparation of tetrafluoroethylene ({C}_{2}{F}_{4}), fluorspar, hydrofluoric acid, and chloroform are combined in a chemical reaction chamber, which is then heated to the temperature of around 600-900ºC. This results in the formation of a gas, which is then distilled to form liquid TFE. The production of TFE is chemically carried out in the following steps:
- By reacting chloroform with anhydrous hydrogen fluoride, chlorodifluoromethane is created.
{CHCl}_{3}(g) + {2HF}(g) → {CHClF}_{2}(g) + {2HCL}(g)
- Since TFE is highly explosive, it is produced on-site, when and where the polymerization takes place, minimizing storage time. Heating chlorodifluoromethane in the absence of air, a process known as pyrolysis, yields tetrafluoroethylene (TFE).
{CHClF}_{2}(g) → {C}_{2}{F}_{4}(g) + {2HCL}(g)
Based on the desired characteristics of the end product, PTFE is prepared via different methods such as suspension polymerisation, controlled emulsion polymerisation, and dispersion polymerisation that results in granular, fine powder, and water-based polymer, respectively. However, the net chemical reaction in all the process remains the same.
Properties of Teflon
The properties of PTFE are dependent on the type of polymer and the method of processing. However, it has excellent properties such as chemical inertness, heat resistance (both high and low), electrical insulation properties, low coefficient of friction (static 0.08 and dynamic 0.01), and nonstick property over a wide temperature range. These properties come from the special electronic structure of the fluorine atom, the stable carbon-fluorine covalent bonding, and the unique intramolecular and intermolecular interactions between the fluorinated polymer segments and the main chains.
- PTFE is a white solid at room temperature, with a density of about 2.2 gram per cubic centimetre.
- PTFE is a very good chemical resistant polymer. This is due to the presence of extremely strong carbon-fluorine bonds. The only chemicals that can affect these bonds are alkali- metals, metals at high temperature, fluorinating agents such as xenon difluoride and cobalt(III) fluoride, and fluorine gas itself.
- PTFE’s mechanical properties are low compared to other plastics, but they remain profitable over a wide temperature range of -100°F to +400°F (-73°C to 204°C). Moreover, properties such as mechanical strength, stability, and wear resistance can be improved by adding fillers such as glass fibres, carbon, graphite, molybdenum disulphide, and bronze.
- Due to the highly symmetric structures of macromolecules, the dielectric constant of Teflon is extremely low (2.1 at 1Mhz).
- PTFE exhibits high thermal stability, which can stand up to the temperature of 440 °C
- PTFE does not exhibit the elastic properties and therefore, tends to change its shape permanently under mechanical stress.
- PTFE is also extremely resistant to Van-der Waal forces. In fact, it is the only material to which even geckos cannot adhere.
Uses of Teflon
1. Electrical Appliances
The electrical industry attributes to at least 50% of Teflon production around the world. Several experiments on Teflon have proved that it has a very high resistance to heat, water, chemical, and heavy wear and tear. These properties of Teflon make it a perfect raw material for wires. The fire resistance property of Teflon protects a large range of electrical devices, such as connectors and instrument control devices. Teflon is used in the production of light fittings, temperature gauges, as well as for a wide range of electrical components. While the dielectric properties of Teflon make it employable in the production of several computer components such as printed circuit boards and assembly cables, the low friction coating of Teflon provides smoother glide to other elements, such as gaming mice balls, writing and drawing tablets, stylus e-pens, and touchpads. Teflon’s exceptionally high bulk resistivity makes it an ideal material for fabricating long-life electrets, the electrostatic analogues of permanent magnets.
2. Cookware
Anyone who has grown up in the modern world might have heard of non-stick pans. It is one of the very initial applications of Teflon and it have become one of the widely used materials in home appliances across the globe. The hydrophobic nature of Teflon makes it a suitable coating for non-stick pans. You might wonder that Teflon does not stick to any food items that you cook in a Teflon pan, but somehow it remains attached to the metal base of the pan. But, in reality, the non-adhesive property of Teflon applies to metallic surfaces also, and there are two techniques to make Teflon stick to the metal surface. The first one is “sintering” in which the Teflon is heated at a very high temperature and pressed firmly onto a surface. When the material cools down to room temperature, it may, eventually, peel away. The second technique includes chemical bonding of Teflon by bombarding it with ions in a high vacuum under an electric field, or “plasma,” which can break away many of the fluorine atoms on the surface that we want to make sticky. Due to its high melting temperature, Teflon is the material of choice for high-performance cookware.
3. Personal Care Products
When you’re thinking of beauty products, the thing that most of them have in common is their slippery texture. Numerous studies have revealed that Teflon can be found as a major ingredient in several beauty and skincare products, such as foundation, pressed powder, loose powder, bronzer, blush, eye shadow, mascara, shave gel, lip balm, and anti-ageing lotion contains Teflon as an ingredient. It is used widely in anti-ageing products and cosmetics, likely because it provides a smooth and sleek finish. Perfluorooctanoic acid (PFOA) is one of the many fluorocarbon compounds that are used as an ingredient in the manufacturing of cosmetics. PFOA is associated with many potentially terminal diseases, like various types of cancer including mammary cancer, reproductive toxicity, and endocrine disruption. Separately, PTFE has not been yet confirmed as a toxic ingredient in cosmetics. However, various research has found evidence that exposures to fluorinated compounds may increase the carcinogenicity of other chemicals when exposures occur together. It is also found in nail polish, likely to provide the shining and glossy look. Apart from cosmetics, Teflon is also found in other grooming equipment such as curling irons, straighteners, combs and as a coating on trimmer blades.
4. Fabric
Whether it’s apparel, carpets, bed-sheets, upholstery, awnings, or patio cushions, almost any fabric around you can be protected from stains or made water-resistant by introducing Teflon in their manufacturing. The quality of fabric for clothing depends to a great extent on aesthetic, durability, and comfort aspect. While aesthetic & comfort performance is desirable in clothing, utility is the key-requirement in fabric. Teflon fabric protector works on a variety of fabric types without interfering with weight, look, colour, or breathability. The lowest coefficient of friction of Teflon successfully repels water and oil and resists unpredictable spills, stains, and splashes. While PTFE is inherently impermeable by water, there is an advanced type of this polymer known as expanded polytetrafluoroethylene (ePTFE) that has a microporous structure that allows the passage of water when it is in a gaseous form. Like normal polytetrafluoroethylene, ePTFE is highly heat-resistant and hydrophobic, and it is also easy to shape into a thin fabric-like material that can be deployed in many more applications than traditional PTFE, which is more rigid. In the textile industry, this polymer has a particular name, GORE-TEX, and it has special properties that make breathable clothes possible. When our body sweats, it emits steam, and this steam can freely move through GORE-TEX, whereas liquid from outside cannot pass through this waterproof fabric.
5. Aerospace Industry
As fascinating as it sounds, exploring new worlds beyond our own is quite a demanding task. The incredibly low temperatures and several harmful cosmic rays can expose the spacecraft to certain vulnerabilities, such as broken signals, malfunctioning electronics, and inoperable mechanics. It can lead to disrupting orbits in the foreign turf, and therefore, it may jeopardize the missions that cost millions of dollars. These issues are addressed by introducing high-performance fluoropolymers that add durability, reliability, and conductivity to spacecraft and satellites. From the cables that help in transmitting images from space back to the Earth to superior thermal control spacewear, Teflon is a material that makes these projects possible. Moreover, Teflon is also a key ingredient to make air travel possible within our atmosphere. It is used in the construction of fuel hoses and tubing facilitates that ensures the safe and durable flow of fuel and other aircraft fluids, respectively. It is also introduced as a coating on airplane wings.
6. Semiconductors
We are surrounded by smart devices that connect our world like never before. As our reliance on these devices grows, so does the demand for high-performance and low-cost semiconductor technologies. The IoT contains millions of devices that are interconnected. This impending industrial revolution is driving demand for increasingly powerful and efficient integrated circuits that will challenge the known limits of design scale and complexity. To satisfy the increasingly strict requirements of greater chip densities and better yields, integrated device manufacturers (IDMs) will depend upon fab system reliability and low defectivity like never before. Teflon improves reliability within the semiconductor manufacturing process, freeing manufacturers to create more innovative and reliable devices. The superior chemical resistance of Teflon ensures that highly corrosive chemicals do not contaminate ultra-clean environments during chip fabrication. The variety of product types (resins, coatings, dispersions, films) in the Teflon family provides a broad range of world-class products that enables the fabrication of semiconductor materials.
7. Musical Instruments
When we talk about musical instruments their precision requires a great deal of time and effort. Various stringed instruments such as Guitar, violin, Viola, Cello, and Indian classical instruments like Sitar require tuning periodically to set their sound frequency right. While we tune these instruments their strings are exposed to friction with the rest of the body. As in most cases, these strings are made up of stainless steel, which is vulnerable to wear. Therefore, Teflon is used as a coating to lower the damage caused by friction. Teflon is also found in the valve oil used to lubricate valves of brass instruments such as the trumpet. It helps in providing a smooth and nearly effortless pressing of valves. In the realm of digital music, the dielectric properties of Teflon insulated wires come in handy to provide excellent music.
8. Ski Bindings
Ski bindings are the part of the ski that straps your foot to the ski. Sometimes it is necessary to be able to slip out of those bindings to prevent injury during a fall. Teflon makes that possible. It works as a non-mechanical Anti-Friction Device (AFD). Generally, it holds the boot firmly to allow the skier to maneuver the ski. However, if certain force limits are exceeded, it releases the boot to minimize skier injuries, such as in the case of a fall or impact. Apart from the safety concerns, the ski industry also uses Teflon to enhance the recreational experience by applying it in a wax form to the skis themselves. When applied on the surfaces of skis PTFE wax reduces friction yet again, thereby increasing the speed.
9. Food Industry
PTFE material (Polytetrafluoroethylene) has a wide range of applicability in food processing and packaging owing to its high chemical resistance and favorable mechanical properties. PTFE plays a key role in enhancing production speed and safety in food manufacturing. These properties, along with the relevant food contact approvals, combine to provide an ideal solution for applications in bakery and food processing contact machinery. Perhaps Teflon does not help in enhancing the quality of food products, but it plays an important part in preserving the quality of food products.
10. Pet Industry
When it comes to your pet’s safety, it’s advisable to employ Teflon-based toys and pet care products rather than toys or products made up of PVC compounds. Teflon is also employed in making artificial habitats for arthropods that they cannot escape easily.
11. Automobile Industry
For its durability and heat and chemical resistant nature, Teflon is highly applicable in the automotive industry. Along with providing protection and durability to a vehicle, Teflon also improves the quality of several vehicle parts, such as axels, ball bearings, chassis, exhaust system, exposed parts on motorbikes and dirt bikes, the exterior of the car, fasteners, gaskets, pistons, seatbelt clips, underbody, and windshield wipers.
12. Chemical Industry
Chemical processing industries provide raw material to a wide range of industrial and manufacturing sectors. One of the challenges they face is the transportation and storage of extremely reactive chemicals. For large scale distribution, the equipment of distribution includes containers, barrels, pipelines, sacks, and small packages. Because Teflon is chemical resistant, it is the perfect resin to coat pipelines, containers, and hoses that transport corrosive chemicals. A variety of Teflon are made so that they do not crack under extreme circumstances. Besides, it doesn’t melt or erode by the chemicals being transported through it. Teflon’s presence in a chemical processing unit is so often that one can say it is irrespective of what kind of chemical is being processed or transported. Not only Teflon ensures a safe and secure environment for chemical transportation, but it also protects several monitoring types of equipment such as sensors, valves, and process vessels.
13. Safety And Security Equipment
Teflon can ensure that your keys do not stick inside the key-hole of a lock.
14. Energy Sector
The global energy demand grows in parallel with the exponential increase in population. To meet continuous supply and demand, it is necessary to ensure an uninterrupted workflow of the heavy machinery involved in oil and gas operations. This problem is addressed by coating Teflon on a variety of substrates, such as carbon, steel, steel alloys, brass, and aluminum. Pipes are coated with Teflon to minimize the accumulation and deposition of asphaltenes and paraffin, and to ensure the continuous flow of fuel. PTFE coated tubing in gas heat exchangers improves long-term hydrostatic pressure performance. It also provides the high-temperature and corrosion resistance necessary for flue gas desulfurization (FGD) in fossil-fueled power plants. In the case of solar energy, the photovoltaic systems in solar cells are covered with Teflon, which makes an excellent substitute for glass. They conduct a high level of light transmittance in the solar cell’s operating frequency range. Teflon also protects from noxious chemicals needed to produce weapons-grade uranium corroded virtually every other material.
15. Medical Sector
Practising medicine and surgery is very delicate and intricate work. Medical practitioners need equipment on which they can rely to operate efficiently. Teflon offers medical-grade coatings that reduce friction as well as incorporate antimicrobials to meet the sterility requirements of medical device makers. There are several types of medical equipment that can benefit from PTFE coatings such as analytical and surgical instrumentation, autoclave and sterilization equipment, and packaging for pharmaceutical products. Furthermore, the porous structure of PTFE can act as a matrix of organic cells and tissue. Its characteristics of having a certain diameter, porosity, and surface microrelief can make organized directional growth in the polymer structure, which allows the organ or tissue to regain lost function. The most obvious example is its use in the treatment of atherosclerosis and vascular substitutes, one of the most prevailing diseases of our time. Teflon also offers a pressure-sensitive adhesive backing, which is installed in strategic high friction areas of footwear, insoles, ankle-foot orthosis, and other medical devices to prevent and relieve friction-induced blisters, calluses, and foot ulceration. Moreover, ePTFE membranes have shown the potential to treat glaucoma in several trials. It is also used in the manufacturing of certain types of dental floss.
16. Construction
From bridges, dams, pipelines to household infrastructure, PTFE offers exceptional reliability and durability through extreme weather, loads, and shocks. With the evolution of engineering and environmental standards, there has been a prominent increase in demand for Teflon in construction. A PTFE-coated screw will be resistant to corrosion due to PTFE’s ability to repel water and oil. Also, lubricated by the same material, it will drive smoothly into whatever surface you are fastening it to. With reduced friction, there will be less wear on both the screw and the surface, which will provide a long-lasting and more secure finish. Generally, in construction and infrastructure, PTFE’s main applications are for providing friction-control performance wherever components move relative to one another. For instance, in the fabrication and erection of steelwork to minimize the stresses produced by the imperfect alignment of steel members, in expansion joints, slide bearings, bridge bearings and dams, and gaskets. It can also be used as an insulator to prevent thermal bridging, e.g., where a pipe passes through an external wall. As a lubricant, PTFE is used to reduce friction and wear. One of the tallest bridge structure in the world, Millau Viaduct, exploits many properties of PTFE. Another widely exploited application of Teflon in modern-day construction is Teflon covered glass. PTFE-coated glass is expensive but tends to have a longer life than PVC coated polyester. Also, the non-adhesive property of Teflon reduces the periodic-cleaning cost.
17. Radiometry
Radiometry is a set of techniques for measuring electromagnetic radiation including visible light. The capability of PTFE to diffuse transmitting light almost completely over a wide range of wavelengths, from UV up to near-infrared, helps in optical radiometry. Therefore, sheets made from PTFE are used as measuring heads in spectroradiometers. In this spectral region, light transmitted through LD PTFE behaves like a Lambertian diffuser. Thus, PTFE enables cosinusoidal angular response for a detector measuring the power of optical radiation at a surface such as in solar irradiance measurements. Moreover, the constant properties of LD sintered PTFE from the ultraviolet (UV) to the near-infrared (NIR) make it attractive in many radiometric applications.
18. Military Applications
Teflon was discovered during the second world war, which justifies its forefront presence in military and defence. The full extent of the technical complexities surrounding military equipment cannot be underestimated, and therefore, such demands are complemented by the selection of enhancement products. From aircraft fuel pump systems to manufacturing tooling, the PTFE lineup offers solutions to some of the major problems design engineers face. Also, the safety of military personnel and their ability to successfully complete missions rely on the equipment they use. The temperature insulation property of Teflon protects soldiers from extremely harsh weather conditions around the world. Teflon is also employed in making bulletproof vests and armour. Teflon resin is creep-resistant, stiff, and inert to chemical attack, making it an excellent choice for handling the intensive conditions faced by the military. Due to its ability to provide a nearly frictionless surface even under extremely high temperature, Teflon coating is provided inside the barrel of many firearms also.
19. 3-D Printers
3D printing is a revolutionary mainstream technology in the industrial sector. The complexity of 3D Printing is as fascinating as the process itself. Fabricating an object layer by layer, according to a digital “blueprint” downloaded to a printer, allows not only for limitless customization but also for designs of greater complexity. The extruder is one of the most important components of a 3D printer. It is responsible for sending the correct amount of filament to the hot end where it’s melted and extruded down in thin layers to make a part. A Bowden extruder is a type of filament feeding mechanism used in many 3D printers that pushes filament through a long and flexible PTFE (Teflon) tube to the hot end. Its low friction allows the extruder stepper motor to push filament through it more easily. They also have less chance of tangling the filament while it unwinds from the spool. This allows for faster changes in the print head movement direction, increased print speed, increased accuracy, and decreased instances of artifatcing or ghosting along the x and y axes.
20. Miscellaneous
There are a million other uses of industrial Teflon coatings that can provide benefits outside of the kitchen from smooth and lubricated surfaces to protective barriers, chemical resistance, dielectric strength and more. Some of them are mentioned below:
- Powdered PTFE is employed in pyrotechnic compositions as an oxidizer with powdered metals like aluminium and magnesium.
- PTFE is employed in making toys and a number of other games like carrom board, Rubik’s cube, fuse ball, and air-hockey, which necessarily requires a lubricated surface.
- Teflon, thanks to its thermal resistivity, is applied as a coating underneath a clothing iron to supply smooth ironing.
- PTFE is widely used as a thread seal tape in plumbing applications, largely replacing paste thread dope.
- PTFE has been experimented with for electroless nickel plating.
- When it comes to artificial jewelry, PTFE is considered a safer option than other compounds as the jewelry made up of PTFE is durable, heat and corrosion-resistant, and at the same time, they give an elegant look.
- PTFE is employed in some aerosol lubricant sprays in micronized and polarized forms. It’s notable for its extremely low coefficient of friction, its hydrophobic nature (which serves to inhibit rust), and for the dry film, it forms after application, which allows it to resist collecting particles that may otherwise form an abrasive paste.