Fluoropolymers are at the high end of engineering plastics. They have very high resistance to chemicals, exceptional weather resistance (the carbon-fluorine bonds are higher in energy than the sun’s UV wavelengths), high temperature resistance, low friction surface, high resistance to burning, low permeability to water and oxygen, and high resistance to abrasion.

They owe their strength to the carbon–fluorine links in the polymer chain, which provide one of the strongest chemical bonds and are very stable. In polymers such as polytetrafluoroethylene (PTFE) and perfluoroalkoxy (PFA), the substitution of hydrocarbons (hydrogen-carbon) with carbon-fluorine is complete. In others, it is limited, and the proportion of substitution can help to predict properties. Except in the case of fluoroethylene vinyl ether (FEVE), which has only 25-30% substitution, but maintains exceptional resistance to UV and weathering as a cross-linked thermoset polymer.

They are available in a range of formats, from moulding resins to fibres and films. They are often combined with other polymers, to impart their impressive properties, but at a lower price point. For example, polyvinylidene fluoride is combined with polymethyl methacrylate, acrylic, (PVDF/PMMA) to make a durable coating used in automotive and architectural applications.

An advantage of fluoropolymers is that, in many cases, they do not require the use of stabilisers, plasticisers, lubricants or flame-retardant additives. This makes them relatively straightforward to recycle.

Discovered almost by accident, fluoropolymers have unique properties that have been developed for diverse applications ranging from life-saving healthcare to water-proofing, breathable fabrics (Gore-Tex), stain-resistant fabrics and carpets (Scotchgard), super-strong architectural fibres, non-stick coatings (Teflon) and super-durable weather-resistant paints used on buildings and bridges. However, they use polyfluoroalkyl substances (PFAS) in their production – although to a slightly lesser extent in fluoroethylene vinyl ether (FEVE). Also known as ‘forever chemicals’, these hazardous ingredients are found in many industrial materials and applications, and do not degrade or break down – they are shown to be extremely persistent in both the environment and in the human body. In fact, it can already be found in the blood of people and animals all over the world, and small amounts in some food products. There are many different types of PFAS and the most commonly studied are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) – also known as C8, for their eight-carbon chain structure. These two in particular, with their long chains, are considered so dangerous that production has now been largely phased out in the US and there is a trend among global manufacturers to replace them with shorter chain PFAS or non-PFAS products. The eye-opening documentary, The Devil We Know, looks at allegations of health hazards from these chemicals, in particular around the Dupont Teflon manufacturing facility in West Virginia, US.

There are alternatives available in most applications. Non-fluoropolymer coatings, such as for buildings, bridges and wind turbines, include polyurethane resin (PUR), polyvinyl chloride (PVC) and epoxy. Unfortunately, these three have hazardous issues of their own, just not as serious as PFAS. For powder coating and cable sheathing, polyethylene (PE) and PVC provide lower cost and lower performance alternatives. In films, such as for solar panels, alternatives include polyethylene terephthalate (PET), polyester, and polyamide (PA), nylon. While these materials are not as durable, they are much less expensive.