Researchers found extraordinary adhesion properties of graphene
A group of researchers at the University of Colorado Boulder (CU-Boulder) discovered that the extreme flexibility of graphene allows it to conform to the shape of the smoothest surfaces. Its powerful adhesion qualities are expected to help guide the development of graphene manufacturing and of graphene-based mechanical devices such as resonators and gas separation membranes.
“The real excitement for me is the possibility of creating new applications that exploit the remarkable flexibility and adhesive characteristics of graphene and devising unique experiments that can teach us more about the nanoscale properties of this amazing material”, said Scott Bunch, Assistant Professor at the CU-Boulder mechanical engineering department.
Adhesion energy describes how “sticky” two objects are when placed together. The CU-Boulder team using a pressurized “blister test” to quantify the adhesion between graphene and glass plates. According to their results, the measured adhesion energy of graphene sheets ranges from one to five atomic layers.
The direct experimental measurements of the adhesion of graphene nanostructures, showed that van der Waals forces clamp the graphene samples to the substrates and also hold together the individual graphene sheets in multilayer samples. The researchers found the adhesion energies between graphene and the glass substrate were several orders of magnitude larger than adhesion energies in typical micromechanical structures, an interaction they described as more liquid-like than solid-like.
Not only does graphene have the highest electrical and thermal conductivity among all currently known materials, but other research groups have shown that it is also the thinnest, stiffest and strongest known material in the world, as well as being impermeable to all standard gases. It’s newly discovered adhesion properties can now be added to the list of the material’s seemingly contradictory qualities.
There is interest in exploiting graphene’s incredible mechanical properties to create ultrathin membranes for energy-efficient separations such as those needed for natural gas processing or water purification, while graphene’s superior electrical properties promise to revolutionize the microelectronics industry.
In all of these applications, including any large-scale graphene manufacturing, the interaction that graphene has with a surface is of critical importance and a scientific understanding will help push the technology forward.
For more information, read the article published in the Nature Nanotechnology named: “Ultrastrong adhesion of graphene membranes”.