2D materials, the new frontier
In materials research, two dimensional materials have researchers digging deep to determine their potential. This relatively new family of materials has opened up a world of possibility smaller than the eye can see.
Two-dimensional materials refer to a family of materials that are stable at an atomic or molecular level, which is the absolute thinnest a material can be. These materials are no more than a few nanometers thick, and are very strong due to their in-plane bonds. However, these strong in-plane bonds only allow the atoms to create weak van der Waals bonds between layers when they are stacked, which can result in a slippage of the layers. This slippage is a property called superlubricity.
A couple examples of these materials are graphene and molybdenum disulfide. Graphene is an atomically thin sheet of carbon arranged in a hexagonal lattice, and was the first 2D material to be isolated to a single layer. Graphene is conductive and often used in nanoscale electronics research. Molybdenum disulfide consists of two layers of sulfur sandwiching a layer of molybdenum. This semiconductor also has piezoelectric properties, making it useful in electromechanical applications.
Because these materials are on the level on a few atoms thick, they are the ultimate size limit of both mechanics and electronics. They have begun to be used in nanoscale electronic and electromechanical devices. The limits of these materials are still being tested, but some researchers hope to one day use them to create flexible electronics, such as wearable electronics or tattoos with biosensors.
While these 2D materials seem like the obvious way of the future, there is a reason that they aren’t being put to use in industry just yet. The process used to create these materials is called chemical vapor deposition, which involves high-temperature gases at low pressures to create a chemical reaction. Because of this and the imperfections in the recipes used to make the materials, it is nearly impossible to control defects on such a small scale. Sometimes you get patches of multilayers and sometimes the substrate that the material is grown on cause defects. Not only that, but many different research groups have their own methods of manufacturing these materials, so there is no standardized way to create these materials, and recreating results from a different lab group is sometimes difficult.
Here at MechSE, we have many professors researching two dimensional materials and their applications.
Professor Arend van der Zande is currently researching nanoelectromechanical systems (NEMS) and the mechanical properties of slippage in heterostructures, which consists of layers of different two dimensional materials.
Professor Sam Tawfick is currently researching how to create composites using these 2D materials as a reinforcing agent to create materials that are both strong and tough.
Alongside Professor Elif Ertekin, Tawfick is also working to create a database of the recipes used to produce these materials using artificial intelligence to find trends in recipes to determine a cost-effective recipe and possibly make a guide for future recipes that could be used in large-scale 2D material manufacturing.
Professor SungWoo Nam has many projects involving research with nanomaterials applications and their morphology, which involves testing the properties of patterned or folded 2D materials to determine how it affects their functionality.
I want to give a special thanks to Professor van der Zande, Professor Tawfick, Professor Nam, Juyoung Leem and Keong Yong for helping me gather the information for this blog.