The University of Trento helps reveal the secrets of aerographite
Aerographite, discovered in 2012 by researchers from the universities of Kiel and Hamburg, is a carbon-based material, although to make it the researchers started from zinc oxide, around which the material was moulded. One of the authors explains: “Think of aerographite as a net of ivy waving around a tree. Then remove the tree.”
Zinc oxide, converted into a crystal, acted as a skeleton: the crystal, carbon was nebulized in carbon in gaseous form, forming a thin layer of graphite. At the same time, hydrogen was injected that, by reacting with zinc oxide oxygen, released vapor and zinc in gaseous form, causing the skeleton around which the graphite was deposited to crumble and releasing a carbon-based structure consisting of individual 'building blocks’, called tetrapods.
The material obtained has very peculiar features: it’s black, super flexible, hydrophobic, highly conductive. But aerographite is most of all extremely light: it weighs 0.2 milligrams per cubic centimetre, that is up to 6 times lighter than air and 75 times lighter than polystyrene and it is considered the lightest material ever invented.
Being light and resistant at the same time, thanks to its structure, aerographite is considered an extremely interesting material for its diverse possible applications. It can be used, for example, in ultra-light batteries for cars and e-bikes, mobile devices, models of biological scaffolds for medical applications, filters to treat air, oil or water containing pollutants and impurities, and even in foams to be used to reduce the impact of micrometeorites on space crafts. The Italian Space Agency (ASI) finds this latter aspect particularly interesting.
An international study, which also involved Stefano Signetti, PhD candidate and member of the research group of the Department of Civil, Environmental and Mechanical Engineering of the University of Trento led by Nicola Pugno, project coordinator, funded under the Graphene Flagship consortium, Kiel, Hamburg and Latvia universities, resulted into a step further in the understanding of the mechanics of tetrapods, the individual structural components of aerographite.
The study, published in Nature Communications, the University of Trento focused mainly on the analytical and numerical modelling of the nanomechanics of tetrapods that with their peculiar tubular morphology, behave therefore like a sort of “elastic zipper” on a strongly inflexed structure. Modelling showed the reaction of tetrapods of different size and shape when under compression or tension, and when in contact with other tetrapods thus providing precious information about their behaviour in order to devise new types of aerographite with even better mechanical features.
Project coordinator Nicola Pugno is very satisfied with the work of Stefano Signetti: “I am very proud of his work. I selected him during a project set up by the Alta Scuola Politecnica, and he followed me to Trento since the beginning, to work on his doctoral program. He has put a lot of commitment and effort in this project and achieved excellent results. He is a black belt, second dan, in ju-jitsu, and maybe this helped him to keep up with the pace of the lab: meetings sometimes were held while biking uphill in the evening sun”.