Adhesion Matters - Sealing the Smallest Molecule: Adhesives for Hydrogen & Fuel Cells

Episode Date: August 24, 2025

How do you seal the most elusive molecule in the universe? In this episode of Adhesion Matters, we explore the unique role adhesives and sealants play in the hydrogen economy. From membrane–electrode assemblies (MEAs) in fuel cells to valves, pipelines, and high-pressure tanks, hydrogen’s small size creates extraordinary challenges: permeation, embrittlement, and cyclic fatigue. We highlight sealant chemistries that can stand up to these demands—including silicones, fluorosilicones, and hybrid polymers—and explain how companies like Dow and Henkel are engineering hydrogen-ready sealing solutions. We also dive into ISO and SAE test standards that define allowable leak rates and durability benchmarks, and look ahead at innovations such as self-healing sealants and seal-in-place gasketing.  Whether it’s cars, trucks, ships, or stationary power, hydrogen fuel cells depend on adhesives that keep the smallest molecule safely under control. This episode shows how the right chemistry is critical for scaling the hydrogen future. 

Welcome back to the deep dive. Today, we're diving into, well, a really fascinating paradox, hydrogen. You know, it's the smallest element on the periodic table, but somehow it creates some of the biggest, most complex ceiling dilemmas imaginable. We're going to pull back the curtain a bit on the hidden world of advanced adhesives and sealants. These are kind of the unsung heroes, absolutely essential for making the hydrogen economy safe, efficient, and, you know, truly scalable. Exactly. And our mission today really is to guide you through the, let's say, the intricate material science behind keeping hydrogen contained. We'll look at the specific innovations.

The industry collaborations, too, we've got insights from key players like Bodomuller, Chimmy, Dow, Henkel, companies really working to overcome these challenges. Yeah, the goal is to leave you thoroughly informed on this pivotal technology. Understanding the fundamental hurdle, sure, but also appreciating the ingenious solutions, making it all possible. Okay, so we started by calling hydrogen a paradox. Tiny element, huge challenges. Let's unpack why. What makes this smallest of elements such a, well, such a nightmare to keep contained? Why is sealing it effectively so incredibly difficult? It really all boils down to its inherent characteristics. I mean, as the smallest molecule, hydrogen has exceptionally high permeability. What that actually means is hydrogen molecules can just sort of slip through materials that would easily hold back much larger. gases. It's like imagine trying to hold water in a fishing net but on a molecular scale. These tiny hydrogen particles are just constantly probing, looking for any micropathway out. So it's not just finding a way out. It's always trying to find a way out, even through

materials that seem solid. Precisely. And it gets worse. Beyond just escaping, there's a much more, well, insidious problem. Hydrogen embrittlement. This is a really critical phenomenon where hydrogen atoms don't just leak past the material. They actually diffuse into. it. Into the seal, yes, but also into adjacent metals. And when these hydrogen atoms get inside the material structure, they can weaken the atomic bonds, especially under cyclic loading, you know, pressure changes again and again in a tank or pipeline. This process, it compromises the material's toughness, makes it brittle, and highly susceptible to sudden failure. So we're not just talking about a slow leak. We're talking about potentially undermining the structural

integrity of the whole system. And frankly, that's why your standard elastomers, your typical sealants, they often just aren't up to the job. They weren't designed for this kind of dual attack. Right. So if hydrogen weakens both the seal and the metal next to it, does that mean we need completely new types of metal alloys to? Not just bitter sealants. Is it a dual challenge? That's a really sharp point. Yes. While today we're focused on the adhesives and sealants, you're absolutely right. The broader hydrogen economy often demands specialized alloys and materials throughout the system specifically designed to resist this embrittlement. It's definitely a multifaceted material science puzzle, and seals are a very visible, very critical piece of it.

Okay. That makes total sense. So we're talking serious risks then, not just losing efficiency, but real safety concerns, especially at those weak points like, say, threaded connections, where even a microscopic leak could be disastrous. Exactly. And if we zoom in on a key application like fuel cell stacks, the role of these adhesives and sealants becomes even clearer. Think about the core of a fuel cell. The membrane electrode assembly, the M-EA, you've got hydrogen, oxygen, and coolant channels all packed tightly together, often under pressure. Maintaining absolutely perfect gas-tight separation between them isn't just important. It's, well, it's non-negotiable, for performance and definitely for safety. Okay, so even tiny breaches in that M-EA, what does that

actually lead to? What are the real-world consequences? Well, even minuscule leaks there can cause significant efficiency drops right away because the gases mix and compromise the reaction. This quickly leads to performance degradation. It shortens the life of these, frankly, very expensive fuel cell stacks. And in the worst case, yeah, complete system failure or safety issues. It hits the economics and the safety case hard. Wow. Okay. So the slippery nature of hydrogen plus this impredalment. Yeah. It really makes standard sealing methods insufficient, which means we need some seriously advanced material science. So, How are engineers tackling this?

What are the key chemistries, the product innovation, stepping up to the plate? And who's behind them? Yeah. This is where the innovation is really exciting. We're seeing several categories of advanced solutions emerge. Companies like Dow, Henkel. They're really at the forefront here. And importantly, you have trusted global partners, specialists in advanced adhesive tech like

Bodo Miller-Chimmy, who are key in actually recommending and distributing these cutting-edge solutions, getting them into the right hands in industry. Okay, before we get right into sealing the hydrogen itself, Let's touch on managing heat because these systems run hot, right? Our sources talk about something called dousal Tc3065 thermal gel. What makes this specific silicone gel stand out for thermal management, especially maybe in manufacturing? Ah, yes, the douselal Tc 30065 thermal gel. It's quite an interesting material.

It's a one part thermally conductive gel, easy to dispense, curable, primarily for dissipating heat, keeping things cool. But the really key property, the thing that makes it stand out is its rework. ability. It cures into this kind of elastic pad. Alastic pad. Yeah, and you can peel it off completely. No residue left behind. Think about what that means for manufacturing. Ah, okay, so if something goes wrong with a component. Exactly. You can salvage it. Reclaim damaged or defective units like complex PCB assemblies. It prevents scrapping expensive parts, speeds up prototyping. It's a huge deal for reducing waste and cost and boosting innovation speed. That reworkability sounds like a game changer, honestly. Not just cost, but speed

and quality control. What about its main job? The thermal performance. Right. It's not just about fixing mistakes. It delivers excellent thermal performance too. It has an impressive 6.5 watts per meter Kelvin thermal conductivity. That's crucial for keeping power devices cool under load. It's often used as a thermal interface material, say for optical transceivers or just general thermal management on PCB systems. And it's durable. Resist humidity, harsh environments, doesn't crack or slump. Plus, it's flexible in how you apply and cure it. Automated dispensing, screen printing, you can cure it relatively quickly at higher temps like 120 degrees C or take longer at, say, 100 degrees C. It even has a long working time over five days at room temp, which gives manufacturer's flexibility. And temperature-wise,

it's built for 9 at 4-5, up to 150 degrees C long term, potentially even colder after checks. So yeah, a very robust solution all around. Okay, super comprehensive for the heat side of things, performance, and manufacturing friendliness. Now let's pivot back to sealing the actual hydrogen, inside the fuel cells. Dow also has a DAO-C-TC-3065 series, but this sounds like it's specifically for fuel cell membranes and gaskets. What's the advanced chemistry doing the work here?

Yes, that specific docile TC-3-Zy65 series for fuel cells uses what are called saline-modified polymer adhesives. Think of them as advanced polymers with silicon components basically engineered for extreme durability and chemical stability in harsh environments. But the critical feature,

and I really can't stress this enough for fuel is there are incredibly low outgassing. Low outgassing. Why is that so vital there? Because even tiny amounts of release chemicals or outgassing inside a PM fuel cell can contaminate sensitive components like the catalyst. This acts like a poison, degrading performance over time, drastically shortening the stacks life, leading to premature failure. It's absolutely critical for long-term reliability and the economics of these systems. So these materials provide strong ceiling, robust performance, especially in demanding areas like heavy-duty

hydrogen transport. They really tackle those core challenges in fuel cell design head on. They're valued for durability, chemical stability, temperature resistance. It reinforces Dow strength in this area within their wider Dow cell range. Got it. That outcasting point really clarifies the so what for system longevity and cost. Okay, let's tackle another big one. Thread sealing. You flagged it earlier as a P failure point. Microscopic leaks, there are a serious risk, right? Especially across the whole hydrogen infrastructure. Our sources highlight Henkel's All-C-T-I-T-T-I-T portfolio, recommended by Boto-Muller-Kemie here. What specific Law-C-T-E solutions are tackling this challenge?

Right, for those critical threaded connections, and there are loads of them in any hydrogen system, Henkel's Al-C-C-T-E range, as highlighted by Bodomuller-Kemey, offers several options that are actually hydrogen certified, and that certification is key. They meet QA-GAS-TEC-Q-Q-A-R-R-214. that's a tough, globally recognized standard specifically for hydrogen service. It proves they can handle it. Okay, so what are some examples? Well, first up, there's LLCT-55.

This one's quite unique. It's not a paste or liquid. It's a non-curing multifilament thread seal cord. A cord, like a string. Sort of, yeah. You wrap it around the threads, the big advantage. It gives an immediate full-pressure seal, but you can still easily readjust the fitting later without damaging the threads or losing

the seal integrity. Really handy for high-pressure hydrogen fittings, precise alignment might be needed during install or maintenance. Interesting. Okay. What else? Then you have Locte 567. This is a high viscosity paste. It's an anaerobic cure. Meaning it cures without air. Exactly. Cures when it's confined between metal threads. It's designed for lower pressure instant sealing on threaded pipes. Works with both common thread types, BSPT and NPT,

and it's got that gas tech hydrogen certification. Okay. Similar but different is Loxt D.T. 577. This one's yellow, also an anaerobic. paste, but offers medium strength, and it's particularly good at resisting vibration. Seals and locks metal threads, great chemical resistance, also hydrogen certified. Got it. Medium strength, vibration resistant. And finally, logteat, 638.

This is a green anaerobic adhesive, known for its really high sheer strength. While its typical job might be retaining bearings on shafts, its super strong bond makes it excellent for ensuring high pressure or extreme environment. threaded connections and hydrogen systems stay absolutely leakproof, provides that extra layer of security. So what's really interesting here is the range. You've got this flexible cord for adjustability, then different paces for varying pressures and strengths, right up to a high-strength adhesive. It feels like a whole toolkit supporting designers across fuel cells, valves, pipelines, the whole infrastructure. That adjustability of the locked TTO 55 sounds super practical, especially for fieldwork.

But does using a cord like that involve any tradeoffs, say, compared to a fully cured, paste for really high pressures. That's a very insightful question. Yes, there are trade-offs, as always, in engineering. Loss PD-55 is brilliant for that immediate seal and the ability to readjust think-sensor fittings or complex piping where you need to tweak angles. But for the absolute maximum pressure containment or situations where you need a permanent rock-solid bond and you know you won't need to adjust it later, then yes, an anaerobic paste,

like the high-strength, LOX-T-638, once fully cured, might provide that ultimate level of security. It really depends on the specific applications demands and the risk assessment. You pick the right tool for the job. Right. It highlights how many different engineering needs there are. But, you know, just developing these fancy materials isn't the whole story, is it? You mentioned certification. Rigorous testing and global standards must be absolutely critical for safety and performance. Oh, absolutely. The regulatory and standards landscape is fundamental. You can't just say it works. You need proof. We're talking about crucial standards like ISO-1467 that defines hydrogen fuel quality itself, which affixed materials, and SAE, J-2601, which covers safe fueling

protocols. Beyond that, you need standards that set allowable permeation thresholds, leak rates for things like automotive fuel cells. Given how licky hydrogen is, you need clear benchmarks for safety. Makes sense. And then underpinning all that are robust regulatory frameworks, you know, EU hydrogen safety rules, Japan's Mithi-I guidelines, U.S. Department of Energy Test standards, they all work together to ensure these technologies are deployed responsibly and reliably everywhere. Yeah, it's clear that this strong regulatory net is essential for public trust and widespread adoption.

It's not just making a good seal. It's proving objectively that it can stand up to the toughest demands day after day. So if we connect all these dots, the material science, the specific products, the standards, what's the bigger picture? Where is this heading? How are these adhesive and sealant innovations actually shaping the future of hydrogen, making more viable across different sectors? Well, the impact is becoming really broad.

In mobility, we see their importance daily in fuel cell cars, trucks, buses, not just sealing the stack, but also integrating those high-pressure tanks safely. And it's pushing into tougher areas, too, like hydrogen aviation and marine applications. Think about the vibration, the temperature cycles, the constant pressure changes there. The ceiling challenge is immense. Beyond transport, these materials are vital for stationary power, backup energy systems, and really for the entire hydrogen-ready infrastructure. Compressors, pipelines, valves, they all need to. to handle hydrogen safely and reliably. And looking ahead, our sources hint

at some really cool future possibilities. Things like adhesive-enabled seal in place gaskets imagine simplifying assembly and boosting durability that way, or even self-healing sealants designed for super long service life. That could really push the boundaries of reliability and reduce maintenance needs significantly.

You know, it raises this fundamental question, just how much do these often invisible technologies, these advanced adhesives and sealants, underpin the entire scalability and safety the hydrogen economy. How are they turning this notoriously difficult molecule into a practical energy solution, silently making it all work? Wow. What an incredible deep dive. It really drives home that sealing hydrogen isn't some minor detail. It's a massive material science hurdle. And these advanced adhesives, these gels, these thread sealants, they are absolutely critical

enablers. They're right at the heart of making a safer, cleaner, and genuinely scalable hydrogen future actually happen, quietly bridging that gap from potential to reality. Exactly right. And maybe a final thought for everyone listening. Consider how these invisible heroes we talked about today, the adhesives, the sealants, are working silently behind the scenes. They're making something as tricky as hydrogen practical for everyday use. So what other invisible technologies, things we barely notice, are shaping our future in profound ways, making this seemingly impossible possible? That's an excellent thought to chew on.

reminder of the hidden ingenuity all around us. We definitely encourage you to keep exploring these fascinating topics. The whole world of material science is just full of surprises. Until next time on the deep dive, keep digging deeper.