(Nanowerk Spotlight) For industries that rely on precision and high performance, adhesives capable of withstanding extreme heat without weakening or leaving residues have been frustratingly out of reach. In electronics manufacturing, aerospace, and other high-tech fields, the lack of reliable high-temperature adhesives has forced engineers to work around this problem for years, limiting their ability to push materials to their full potential.
Now, by mimicking nature’s design, researchers have developed a breakthrough solution: an adhesive inspired by the intricate structures found in beetles, able to maintain strong, clean adhesion at temperatures beyond 200 °C.
Their approach leverages bioinspiration, drawing from the adhesive properties of the beetle Dytiscus lapponicus, which uses tiny suction cup-like structures on its legs to adhere firmly to surfaces. These structures, coupled with a material composition based on fluororubber (FKM) and carbon nanotubes (CNTs), enable the adhesive to perform exceptionally well across a broad temperature range, from room temperature to over 200 °C. This development could mark a shift in how industries manage tasks like handling delicate, heat-sensitive materials without contamination, especially in environments where conventional adhesives fail.
The problem of adhesion at high temperatures has long been a roadblock for manufacturing processes that involve delicate materials like silicon wafers or glass substrates, which are used in electronic devices and displays. Traditional adhesives, often made from polymers like polydimethylsiloxane (PDMS), are flexible but begin to degrade and lose their adhesive properties at elevated temperatures. This not only weakens their grip but also risks contaminating the surfaces they are meant to bond, leading to costly defects in high-precision applications. The need for an adhesive that is both heat-resistant and residue-free has driven researchers to explore new materials and designs, often turning to nature for inspiration.
The research team’s solution centers on a nanocomposite material that mimics the natural adhesive structures of beetles. These structures feature a “suction cup-shaped” tip that enhances the adhesive’s ability to stick to surfaces without relying on chemical bonding or sticky residues. The fluororubber-based adhesive incorporates nanofillers like carbon nanotubes, which allow the researchers to fine-tune its mechanical properties. By adjusting the concentration of CNTs, they can control the adhesive’s elasticity, which in turn affects how well it conforms to different surfaces.
Preparation of the bioinspired adhesives. a) Bionic object–Dytiscus lapponicus and SEM images of the adhesive structures in its attachment pads. b) Preparation procedure for the bioinspired adhesives. c) Photograph and scanning electron micrographs of the bioinspired adhesives. (Image: Reproduced with permission by Wiley-VCH Verlag)
The key challenge with high-temperature adhesives is finding a balance between flexibility and strength. Adhesives need to be flexible enough to create a large contact area with the surface, which enhances their grip, but they must also be strong enough to maintain that grip as temperatures rise. Too much stiffness can reduce the contact area, while too much flexibility can weaken the adhesive’s hold.
The research team addressed this by carefully regulating the amount of CNTs in the adhesive, allowing them to adjust its modulus (a measure of stiffness) to suit different temperature conditions. At 1% CNT content, the adhesive demonstrated the highest performance, achieving adhesion strengths of over 350 kPa, far surpassing previous bioinspired adhesives.
What sets this adhesive apart is its ability to maintain strong, contamination-free adhesion even at temperatures exceeding 200 °C. Conventional adhesives either degrade or soften when exposed to such heat, which can cause them to lose their grip or leave behind unwanted residues that interfere with precision applications. The fluororubber-based adhesive developed by the research team not only avoids these pitfalls but actually improves its performance at higher temperatures. This is due in part to the way the material’s structure changes with heat: as the temperature rises, the adhesive’s elastic modulus decreases slightly, which allows it to form a larger contact area with the surface and enhances its overall grip.
The design of the adhesive’s “suction cup-shaped” microstructure also plays a crucial role in its performance. When pressed against a surface, these suction cups expel air, creating a partial vacuum that enhances the adhesive’s hold through what’s known as the suction effect. This effect, combined with van der Waals forces, helps the adhesive maintain its grip without leaving any residue. As the adhesive is pulled away from the surface, the suction cups resist separation, providing additional strength. This dual mechanism – van der Waals forces and suction – enables the adhesive to perform well even in high-temperature environments.
In addition to its heat resistance, the adhesive is also remarkably durable. Tests showed that it could be applied and removed from surfaces repeatedly without losing its strength, even at high temperatures. After 100 cycles of adhesion and detachment, the material still retained its adhesion strength, demonstrating its potential for use in automated manufacturing processes where repeated application is necessary. Importantly, the adhesive leaves no residue on the surfaces it adheres to, making it ideal for use in applications where cleanliness and precision are paramount.
The flexibility of the material’s design also opens up possibilities for further optimization. By adjusting the CNT content or modifying the microstructure of the adhesive, the research team could tailor the material to meet the specific needs of different industries. For example, in semiconductor manufacturing, where materials must be handled at high temperatures without contamination, this adhesive could offer a clean, reliable alternative to current solutions. Similarly, in industries like aerospace or automotive manufacturing, where materials are often exposed to extreme heat, this adhesive could provide a way to bond components securely without compromising their integrity.
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