Researchers have developed a new dry adhesive that bonds in temperatures ranging from -320°F to 1,832°F, a quality that could make the product ideal for space exploration where shade can be frigid and exposure to the sun blazing hot. It features vertically aligned carbon nanotubes with tops bundled into nodes that scientists say replicates the microscopic hairs on the foot of the wall-walking gecko.
The research, published in the journal Nature Communications, builds on earlier development of a single-sided dry adhesive tape based on vertically aligned carbon nanotubes.
“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,” says Ming Xu a senior research associate at Case Western Reserve University’s School of Engineering, Cleveland. “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.”
Xu was joined on the research team by Liming Dai, a professor of macromolecular science and engineering at Case Western Reserve; Feng Du, a senior research associate at 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.
The adhesive also conducts heat and electricity, according to the researchers. “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 says.
In testing, a double-sided tape made from the carbon nanotubes (CNTs) and 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°F and increased it six times over at 1,891°F. The adhesive’s strength, according to the team, results as its bundled nodes penetrated surface cavities and its 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.