A day without silicone

You came into contact with silicone this morning. Several times. In the coffee machine's seal. In the shampoo. Perhaps in the contact lenses on your eyes, perhaps in your child's pacifier.

They didn't notice. Nobody notices.

Silicone keeps airplanes in the air, pacemakers beating, and electric cars from bursting into flames. It seals the International Space Station against the vacuum of space. It played a key role in the development of modern heart surgery. It enables the energy transition – and yet it is itself extremely difficult to recycle.

The global silicone market is estimated at $25 to $33 billion.^¹ That sounds like a lot. For comparison, the smartphone market is worth $500 billion. Without silicones, many of these devices would be less robust, many medical systems more complex, and many energy technologies more expensive. A small market that keeps huge systems running.

What if this material simply disappeared tomorrow morning?

I. 6:30 a.m

They reach for the phone. The screen is damp. The silicone seal that protected the casing from dust and water is gone. Moisture seeped in overnight. The display flickers.

The bathroom is dripping. The grout around the shower and sink has disappeared. The coffee machine is leaking. The shampoo feels rough and sticky. Dimethicone is missing – the silicone that gives your hair its softness. You just didn't know it.

The day hasn't even begun, and already the pattern is emerging: silicone is found wherever two materials meet and the bond needs to function. Silently. For years. Without anyone giving it a second thought.

II. The way to work

They get into the car. They turn the key. Nothing.

In an internal combustion engine, silicone caps insulate the spark plug connectors against 20,000 to 40,000 volts. Without them, the spark wouldn't jump – or would jump everywhere. The turbocharger hoses, which have to withstand temperatures over 200 degrees Celsius, are made of silicone rubber. The exhaust hangers, valve stem seals, and cable glands are all silicone.

But things get really serious with the vehicles on which Europe is betting its industrial future.

A modern EV battery pack operates at voltages up to 800 volts. A thermally conductive silicone gel sits between the lithium-ion cells and the cooling plate, dissipating the waste heat. An automatically applied silicone gasket surrounds the housing, ensuring a hermetic seal for over 15 years and tens of thousands of temperature cycles.

Between the individual modules are silicone barriers designed to prevent the most dangerous event imaginable: thermal runaway. A cell can heat up to over 800 degrees Celsius. Certain silicone rubber formulations then do something that no other common elastomer can: they don't burn. They ceramize – forming a ceramic protective layer that delays fire penetration. SAE studies document this effect for ceramifiable silicone composite sheets.²

Instead of accelerating the fire, they slow it down. That's why silicon is now found in virtually every modern EV battery design, precisely where it matters.

III. Waterfalls, War and Sticky Masses

The story of silicone doesn't have one origin. It has three. And they all begin with people who were looking for something different.

The Skeptic. Frederic Stanley Kipping, a British chemist, spent three decades working with compounds of silicon and carbon. What he found were oils and sticky masses that defied categorization. In 1937, in his last publication, he wrote that the prospects were "anything but encouraging." He died without knowing that his sticky substances would decide wars, repair hearts, and seal space stations.

The engineer. Thirty years earlier in Norway, Sam Eyde had laid the foundation for something he himself never foresaw. Trained in Berlin, Eyde had acquired water rights to Norwegian waterfalls in Telemark around the turn of the century. In 1904, he founded the company Elkem with the Swedish banking family Wallenberg – with the aim of harnessing hydropower for the electrochemical industry.^Eyde 's vision was fertilizer. Not silicones. But the company he created would, 120 years later, become one of the world's largest silicone manufacturers.

The war. In 1942, the electrical systems of Allied bombers failed at high altitudes. Moisture on the ignition electronics caused arcing and engine failure. Conventional shellac insulation was useless in cold and wet conditions. Dr. Shailer Bass of Dow Corning developed a silicone grease for spark plugs and wiring harnesses. A simple product. But it enabled flights to altitudes and over distances that had previously been unreliable.

Almost simultaneously, in 1944, chemists from Rhône-Poulenc began their own silicone experiments in a laboratory in Saint-Fons near Lyon – independently of the Americans, using a process based on organic silicates. Industrial production started ⁱⁿ 1948 under the brand name RHODORSIL. ^By 1970, thanks to Saint-Fons, France was the world's fourth-largest silicone producer.

Three strands interwoven over a century. Rhône-Poulenc became Rhodia, Rhodia Bluestar Silicones, and since 2017 the silicone division has been called Elkem Silicones – reunited with the Norwegian parent company, which Sam Eyde founded in 1904 by a waterfall. The plant in Saint-Fons is still in production today.

And then: Silly Putty. In 1943, a GE engineer was looking for synthetic rubber. What he found bounced, copied newspaper print, and shattered like glass under sharp impact. As rubber: unusable. A toy manufacturer packaged it in plastic eggs. 300 million sold. In 1968, Apollo 8 astronauts took it into lunar orbit to fix tools in zero gravity.

From wartime secret to children's toy to outer space. In 25 years.

IV. A sphere, barely larger than a marble

In September 1960, surgeon Albert Starr opened the chest of a 52-year-old man in an operating room at the University of Oregon. What he sewed in was something that had never existed before: an artificial heart valve.³

The idea didn't come from a doctor, but from Lowell Edwards – a retired hydraulics engineer who marched into Starr's office with a sketch. A metal cage with a small sphere inside that opened and closed with each heartbeat. The cage: Stellite, a cobalt-chromium alloy. The sphere: Silastic, a silicone elastomer from Dow Corning.⁴

Before this invention, surgeons could at best attempt to widen a narrowed heart valve with their finger – blindly, through an incision in the beating heart.

The silicone sphere had to open and close with every heartbeat. 100,000 times a day. 36 million times a year. Without fatigue. Without harming the blood. Without being rejected by the body. No other material available at the time offered this overall profile. Metal corroded. Plastics were not biocompatible. Natural rubber decomposed.

The first patient lived for ten years. He died when he fell from a ladder while painting his house.⁵ Not from the heart.

By 1989, over 50,000 of these valves had been implanted – without a single documented case of structural material failure over 22 years.³

A silicone sphere, barely larger than a marble. Thus began a new chapter in cardiac surgery.

V. The Invisible Ring

On May 30, 2020, while the world was in lockdown, SpaceX Crew Dragon docked with the International Space Station. Billions watched. Nobody talked about the sealing.

Fifteen years of development work went into it. Pat Dunlap and Bruce Steinetz led the team at NASA's Glenn Research Center.^The requirements: functionality in a vacuum, extreme temperature fluctuations, UV resistance. And not too sticky – otherwise it would have blocked the docking mechanism. Each ring: cast in a single mold, without seams, because every joint is a weak point.

The material: silicone rubber. A NASA technical report describes silicone rubber as the only class of space-qualified elastomeric sealing materials that functions across the expected temperature range.⁷

Every time a spacecraft docks with the ISS – Crew Dragon, Soyuz, Cygnus – a silicon ring keeps the crew's breathing air separate from the vacuum of space.⁶

Further out: When the Curiosity rover entered the Martian atmosphere in 2012, its heat shield reached temperatures exceeding 2,000 degrees Celsius. The joints between the tiles were sealed with RTV 560 – a silicone rubber. The same class of material used to seal bathroom tiles on Earth held a nuclear-powered robot together as it entered an alien atmosphere. When the Perseverance rover landed in 2021, its thermal batteries contained high-purity silicon from Elkem – manufactured in Norway, landed on another planet.¹⁹

And Neil Armstrong's moon boots? Silicone soles. The most famous footprint in human history, made of a material that 26 years earlier had been dismissed as a "sticky mess".

VI. 73 seconds

On January 28, 1986, an unusually cold morning in Florida, the space shuttle Challenger launched. 73 seconds later, it broke apart. Seven people died.

The technical cause: Viton fluorocarbon O-rings in the solid rocket motor connectors had lost their elasticity in the cold.^Hot combustion gases leaked through the faulty connection. The external tank ignited.

It wasn't just a material failure. It was a combination of joint design weaknesses, known erosion problems, management pressure, and the decision to launch in those temperatures despite explicit engineering warnings. The Rogers Commission documented how the cold significantly reduced the resilience of the O-rings and increased their recovery time.^{8 9}

What is this story doing in an article about silicone?

The answer is inconvenient. Viton is an excellent high-temperature rubber. But it hardens in the cold. Silicone rubber is one of the few elastomers that retains its flexibility down to minus 60 degrees Celsius—precisely the property that was lacking that January morning. Whether silicone would have been the better choice under the specific conditions of the SRB joints can only be answered by a full engineering analysis. But the lesson is universal.

Temperature is a material parameter, not weather. And the consequences of a wrong decision can be irreversible.

VII. The Powder Keg

Now it's getting geopolitical.

China controls over 70 percent of global silicon material production. The trend is toward almost 80 percent.^¹¹ A significant portion originates in Xinjiang. In 2021, U.S. Customs and Border Protection (CBP) issued a Withhold Release Order against silica-based products from the largest Chinese producer, based on information suggesting forced labor.^¹²

Europe produces less than eight percent of the world's silicon metal. But European industry – automotive, medical technology, electronics, renewable energies – is entirely dependent on it. The EU has reacted: The Critical Raw Materials Act lists silicon metal as a strategic raw material,^on the same level as lithium, cobalt, and rare earth elements.

This is where Europe's own production base becomes vital. Elkem operates a network of silicon smelters in Norway – Fiskaa, Thamshavn, Rana, Salten, Bremanger – which are largely powered by the hydroelectric energy that Sam Eyde harnessed 120 years ago.^Wacker Chemie also maintains a smelter there, which covers around a quarter of the company's global demand. These are Europe's most important supply lines for the raw material, without which silicon production is impossible.

As a non-EU member, Switzerland is not covered by the Critical Raw Materials Act. But Swiss industry – precision instruments, medical technology, watches, automotive suppliers – is just as dependent.

Anyone who thinks silicon is a stable, boring commodity market hasn't been paying attention in recent years. Silicon metal prices exploded by around 300 percent in 2021. This could happen again at any time.

VIII. The Paradox

Here, history contradicts itself. And that's precisely what makes it relevant.

Silicones are key building blocks of the energy transition. Without them, there would be no solar panels – each module contains several hundred grams of silicone encapsulation. Without them, there would be no efficient wind turbines, no electric cars, no LED lighting, and no energy-efficient building envelopes.

An industry study by the Global Silicones Council concludes that the greenhouse gas savings achieved by using silicone products are, on average, 14 times higher than the emissions from their manufacture and disposal.^Whether the methodology stands up to scrutiny is debatable – the basic logic is plausible.

But.

Global silicone production is around 3 million tons and is growing by 5 to 6 percent per year. What happens to cured silicone seals after 20 years? To the potting compounds from dismantled solar panels? To the hoses from the engine compartment of a scrapped car?

Landfill. Incineration. Silicone is not biodegradable; it persists in the environment, and the proportion that is chemically recycled is in the low single-digit percentage range. The production of silicon metal requires temperatures of 2,000 degrees Celsius in electric arc furnaces – predominantly powered by coal in China.

The material that makes the green transition possible can hardly be circulated in a circle itself.

Europe's response comes from two directions.

^First : cleaner production. In Rana, northern Norway, Elkem operates a carbon capture pilot project at its ferrosilicon smelter—the first of its kind in the entire silicon industry. The plant is powered by hydroelectricity. It is an attempt to reduce the carbon footprint of an industry whose products reduce the carbon footprint of almost every other industry.

Secondly – ​​and this is the real news: In April 2025, researchers from the University of Lyon and the CNRS, together with Elkem Silicones, published a process in Science. This gallium-catalyzed depolymerization process converts all kinds of silicone waste – including highly cross-linked products such as baking molds – back into basic chlorosilane building blocks at only 40 degrees Celsius.^{^{15 16}}

40 degrees instead of 2,000 degrees. 97 percent yield in the lab. From the baking pan back to the monomer.

Elkem researcher Aurélie Boulegue-Mondière, co-author of the study, works at the R&I center “ATRiON” in Saint-Fons near Lyon.^This is the same location where Rhône-Poulenc conducted the very first silicone experiments in Europe in 1944. The pilot scaling trials are underway at Activation in Chassieu – also in the Lyon region^.

Eighty years after the first European silicon experiments, researchers at the same location are working to close the loop.

If this process is scaled up industrially – and Elkem is not involved out of academic interest – then it would be the first realistic way to a true circular economy for silicones.

The most important materials of our time are often the ones no one talks about. Not because they are insignificant, but because they do their job so well that they become invisible.

Until they are missing.

Companies working with critical materials need more than just a supplier. They need a partner who understands material selection. SILITECH AG supports industrial customers in the DACH region in the selection and supply of silicones, adhesives, sealants, and lubricants – technically sound, pragmatic, and from its own warehouse.

Sources

1. Market estimates vary depending on the definition and time horizon. Grand View Research estimates the global silicone market at approximately USD 24.3 billion in 2025, with a forecast of USD 37.3 billion by 2033. Other analysts (IMARC, Persistence Market Research) cite slightly different figures.
2. SAE Technical Paper (2024) on ceramifiable silicone rubber composite sheets and their effect on thermal runaway propagation in battery packs.
3. Lasker Foundation: "Prosthetic aortic and mitral valves" – entry on Albert Starr and Lowell Edwards. laskerfoundation.org
4. Smithsonian National Museum of American History: Starr-Edwards Heart Valve, object description. americanhistory.si.edu
5. NIH/PMC: “Development of the Starr-Edwards heart valve” (1998). pmc.ncbi.nlm.nih.gov
6. NASA: “Sealed with Care – A Q&A” (Docking Seals, Pat Dunlap, Bruce Steinetz). nasa.gov
7. NASA Glenn Technical Report (2010): Silicone rubber is the only class of space-qualified elastomeric sealing materials across the expected temperature range. ntrs.nasa.gov
8. NASA Rogers Commission Report, Chapter IV: Temperature Dependence of O-Ring Resilience. nasa.gov
9. NASA Rogers Commission Report, Chapter VI: Design and Material of Solid Rocket Booster Joints. nasa.gov
11. USGS Mineral Commodity Summaries – Silicon (2024/2025): China's share of global production >70% (2023), "almost 80%" (2024). pubs.usgs.gov
12. US Customs and Border Protection: Withhold Release Order (2021) against silica-based products. cbp.gov
13. EU Critical Raw Materials Act (2024), Annex I: “silicon metal” as a strategic raw material. eur-lex.europa.eu
14. Global Silicones Council (2024): Industry study on the greenhouse gas balance of silicone products throughout their life cycle.
15. Science (2025): Gallium-catalyzed depolymerization of silicone waste at 40 °C. Vũ, Boulegue-Mondière, Durand, Munsch et al. science.org
16. CNRS Press Release (2025): "Universal recycling process". cnrs.fr
17. Sam Eyde founded Elkem on January 2, 1904, together with Knut Tillberg and the Swedish bankers Knut and Marcus Wallenberg. Sources: Elkem 120th Anniversary (2024); Wikipedia: Sam Eyde.
18. Elkem Silicones company history: First silicone trials at Rhône-Poulenc in Saint-Fons in 1944, RHODORSIL from 1948. elkem.com
19. Elkem 120th Anniversary (2024): Elkem silicon in the thermal batteries of the Perseverance rover. prnewswire.co.uk
20. Elkem Silicon Products: Smelters in Fiskaa, Thamshavn, Rana, Salten, Bremanger, Bjølvefossen, Herøya (NO) and Grundartangi (IS). elkem.com
21. Elkem: Carbon capture pilot project Rana, the first in the silicon industry. elkem.com
22. Elkem (2025): Boulegue-Mondière, R&I Center “ATRiON”, Saint-Fons; Pilot tests Activation, Chassieu. elkem.com