researchers from case western reserve university, dayton air force research laboratory, and huazhong university of science and technology (china) teamed up to develop a new dry adhesive that bonds even in extreme temperature. the gecko-inspired adhesive could be a breakthrough product for use in space travel.
case western researchers developed a dry adhesive that has a nano-interlock ability. (case western university)
the researchers built on previous work on one-sided dry adhesive tape using vertically-aligned carbon nanotubes. bundling the tops of the nanotubes allowed scientists to recreate the microscopic hairs on a gecko, but with enough van der waal’s forces to hold in temperatures ranging from -320°f to 1,832°f, according to a report from the case western website.
in the report, senior research associate ming xu explained, “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.”
the ability to withstand extreme temperature variances could make this adhesive ideal for space, but it also has electrical and thermal conductivity properties that make it a potential step forward as a thermal interface material, in the field of robotics, or even as an adhesive for home appliances.
the researchers tested the strength of the adhesive in the lab at room temperature. on the case western site there is a photo of xu hanging from two wooden blocks that were each stuck to the wall with six double-sided strips of the new adhesive. the double-sided tape was made with carbon nanotubes applied between two layers of copper foil, which had the strength of 37 newtons per centimeter squared.
the strength of the adhesive increased when heated. using a scanning electron microscope, the scientists discovered that when heated the nanotubes are no longer vertically-aligned but drop into a web-like configuration that increases the surface area and enhances the van der waal’s forces. the researchers coined the term “nano-interlocking” to describe this.
in november, the team published its research in nature communications. the abstract stated:
“conventional adhesives show a decrease in the adhesion force with increasing temperature due to thermally induced viscoelastic thinning and/or structural decomposition. here, we report the counter-intuitive behaviour of carbon nanotube (cnt) dry adhesives that show a temperature-enhanced adhesion strength by over six-fold up to 143 n cm−2 (4 mm × 4 mm), among the strongest pure cnt dry adhesives, over a temperature range from −196 to 1,000 °c.
“this unusual adhesion behaviour leads to temperature-enhanced electrical and thermal transports, enabling the cnt dry adhesive for efficient electrical and thermal management when being used as a conductive double-sided sticky tape. with its intrinsic thermal stability, our cnt adhesive sustains many temperature transition cycles over a wide operation temperature range.
“we discover that a ‘nano-interlock’ adhesion mechanism is responsible for the adhesion behaviour, which could be applied to the development of various dry cnt adhesives with novel features.”