A new dry adhesive loses no traction in the cold and becomes stronger in extreme heat. Here’s how: Bundled nodes of carbon nanotubes penetrate surface cavities and form web-like structures likely adding to the van der Waal’s attraction. As the surface heats it becomes increasingly rough, and the bundles appear to penetrate deeper, becoming locked into place and further increasing the adhesion.
Researchers from Case Western Reserve University, Dayton Air Force Research Laboratory and China have developed a new dry adhesive that bonds in extreme temperatures—a quality that could make the product ideal for space exploration and beyond.
The gecko-inspired adhesive loses no traction in temperatures as cold as liquid nitrogen or as hot as molten silver, and actually gets stickier as heat increases, the researchers report.
The research, which builds on earlier development of a single-sided dry adhesive tape based on vertically aligned carbon nanotubes, is published in the journal Nature Communications. As far as the researchers know, no other dry adhesive is capable of working at such temperature extremes.
Liming Dai, professor of macromolecular science and engineering at Case Western Reserve and an author of the study teamed with Ming Xu, a senior research associate at Case School of Engineering and visiting scholar from Huazhong University of Science and Technology; Feng Du, senior research associate in Case Western Reserve’s Department of Macromolecular Science and Engineering; and Sabyasachi Ganguli and Ajit Roy, of the Materials and Manufacturing Directorate, Air Force Research Laboratory.
Vertically aligned carbon nanotubes with tops bundled into nodes replicate the microscopic hairs on the foot of the wall-walking reptile and remain stable from -320 degrees Fahrenheit to 1,832 degrees, the scientists say.
“When you have aligned nanotubes with bundled tops penetrating into the cavities of the surface, you generate sufficient van der Waal’s forces to hold,” Xu said. “The dry adhesive doesn’t lose adhesion as it cools because the surface doesn’t change. But when you heat the surface, the surface becomes rougher, physically locking the nanotubes in place, leading to stronger adhesion as temperatures increase.”
Because the adhesive remains useful over such a wide range of temperatures, the inventors say it is ideally suited for use in space, where the shade can be frigid and exposure to the sun blazing hot.
In addition to range, the bonding agent offers properties that could add to its utility. The adhesive conducts heat and electricity, and these properties also increase with temperature. “When applied as a double-sided sticky tape, the adhesive can be used to link electrical components together and also for electrical and thermal management,” Roy said.
“This adhesive can thus be used as connecting materials to enhance the performance of electronics at high temperatures,” Dai said. “At room temperature, the double-sided carbon nanotube tape held as strongly as commercial tape on various rough surfaces, including paper, wood, plastic films and painted walls, showing potential use as conducting adhesives in home appliances and wall-climbing robots.”
Holding strength
In testing, a double-sided tape made with the carbon nanotubes (CNTs) applied between two layers of copper foil had an adhesive strength of about 37 newtons per cm-2 at room temperature, about the same as a commercial double-sided sticky tape.
Unlike the commercial tape, which loses adhesion as it freezes or is heated, the CNT adhesive maintained its strength down to -320 degrees Fahrenheit. The adhesive strength more than doubled at 785 degrees Fahrenheit and was about six times as strong at 1891 degrees.
Surprised by the increasing adhesive strength, the researchers used a scanning electron microscope to search for the cause. They found that, as the bundled nodes penetrate the surface cavities, the flexible nanotubes no longer remain vertically aligned but collapse into web-like structures. The action appears to enhance the van der Waal’s forces due to an increased contact surface area with the collapsed nanotubes.
Looking further, the researchers found that as the temperature increased above 392 degrees Fahrenheit, the surface of the copper foil became increasingly rough. The bundled ends and collapsed nanotubes appear to penetrate deeper into the heat-induced irregularities in the surface, increasing adhesion. The researchers dub this adhesion mechanism “nano-interlocking.”
The adhesive held strong during hundreds of temperature transition cycles between ambient temperature and -320 degrees then up to 1891 degrees and between the cold extreme and ambient temperature.
Copper foil, which was used for many of the tests to demonstrate the potential for thermal management, is not unique. The surface of many other materials, including polymer films and other metal foils, roughen when heat is applied, making them good targets for this kind of adhesive, the team suggests.
Learn more: Dry adhesive holds in extreme cold, strengthens in extreme heat
The Latest on: Gecko-inspired adhesive
via Google News
The Latest on: Gecko-inspired adhesive
- Setex Gecko-inspired Eyeglass Nose Pads Now Available Wholesale to Optical Retailerson May 19, 2022 at 3:22 am
As far back as Aristotle, researchers have been fascinated by the amazing sticking ability of gecko lizards, and their ability to climb and stick to a wide range of surfaces. Through microscopic ...
- Setex Gecko-inspired Eyeglass Nose Pads Now Available Wholesale to Optical Retailerson May 19, 2022 at 3:08 am
These anti-slip nose pads, produced using high grip materials that were inspired by gecko lizards, were previously available only to consumers through e-commerce channels like Amazon.com ...
- Want it to Work in Space? Better Test it Frequently on Earthon May 18, 2022 at 5:01 pm
Recent tests on the ISS have produced promising results. For example, Gecko-Inspired Adhesive Grasping uses the space station’s Astrobee robots to test grasping and manipulating objects using an ...
- Gecko-inspired adhesive combines strong bond with damage-free, clean removal propertieson May 18, 2022 at 5:01 pm
Akron Ascent Innovations LLC (AAI), a high-tech startup in Akron, OH, has launched an innovative dry-adhesive technology that offers a combination of ease of use, strong adhesion and damage-free, ...
- YouTuber tries to climb a wall like Spider-Man using gecko tapeon May 15, 2022 at 10:03 am
The YouTuber explains how geckos' feet, which inspired nano tape, were for a long time a mystery to scientists because they did not see any adhesives ... nano tape or gecko tape to imitate this ...
- Gripping Microfiber (IMAGE)on May 11, 2022 at 4:27 pm
Researchers have developed a directional adhesive, inspired by the gecko, using microfibers made from a hard polymer, polypropylene. The polymer fibers are 600 nanometers in diameter, just 1/100 ...
- These tiny gecko-inspired robots can lift over 100x their weighton April 23, 2022 at 5:00 pm
The robots feet contain adhesives that manage to hold onto the ... And as you can see in the video below, the bots' movement is also inspired by nature, going forward one step at a time like ...
- How the University of California Harnesses Nature’s Super Powerson March 31, 2022 at 4:33 pm
UC Berkeley Professor Robert Full leads the lab that developed the adhesive. He demonstrated the climbing capabilities of gecko-inspired materials in a TED talk, sharing footage of climbers ...
- PEDALing into the Future: Three applicationson February 27, 2022 at 3:30 am
"We confirmed it is geometry, not surface chemistry, that enables a gecko to support its entire body with a single toe," says Berkeley engineering professor Ron Fearing. That means the adhesive can be ...
via Bing News