New records are constantly being set in materials research: even stronger, even harder or even more elastic materials, maximum load-bearing capacity with the lowest possible density. Complex high-performance composites push the boundaries of what is technically feasible.
In nature, however, things are usually different: it does not necessarily produce materials with extreme material properties, but also takes properties such as durability, reparability and reusability into account. The best bone is not necessarily the hardest, but perhaps the one that heals as quickly as possible.
Research into biogenic materials is being carried out at TU Wien - and the extent to which these basic principles can be taken into account in science and technology has now been investigated. The results have been published in the journal "Advanced Functional Materials".
A wall around the world"The amount of raw materials we use every year is enormous," says Ille C. Gebeshuber, who has been researching bio-materials at the Institute of Applied Physics at TU Wien for many years. "If you were to pile up all this material, from crude oil to minerals and rocks, to form a wall, this wall would be around one kilometer high at a width of one meter and would reach around the equator," Gebeshuber calculates. "And every year this wall would become about 2.8 cm thicker."
This huge consumption of resources is closely linked to how we humans usually select materials: "Often you want to combine different material properties - for example, you want a material that is as strong as possible but not too dense. Then you can look at material science diagrams to see which materials best meet these requirements and then choose a material from the outermost edge of this diagram, for example a certain metal alloy."
However, the same diagram also shows biological materials - usually with somewhat less extreme properties. "The crucial question now is: are these natural materials perhaps still good enough for what we actually need in this specific case?" says Richard van Nieuwenhoven (TU Vienna), the lead author of the current paper.
The somewhat less optimal material properties can be more than compensated for by other advantages - such as better environmental compatibility, greater flexibility and better repair options. "Nature optimizes the whole, not just one or two specific parameters - and this can also be exploited in materials science," says Ille C. Gebeshuber.
Living materialsIlle C. Gebeshuber notes that a new trend is currently emerging in materials research: "Engineered Living Materials" (ELMs) - natural materials that are used for technical applications in a sophisticated, controlled way. For example, there are types of concrete into which special bacteria are incorporated. This may initially impair the material properties of the concrete slightly, but if a crack forms somewhere in the concrete and water seeps in, these bacteria become active and heal the crack. There have also been successful experiments in growing trees in a specific shape in order to adapt their wood for a specific purpose - for example, to make an armchair. In Indonesia, there are bridges that are formed from living plant parts - this creates a load-bearing network of flexible branches and lianas that would certainly not withstand a railroad, but is perhaps a better, more durable and lower-maintenance solution for use as a footbridge.
"The more closely we study natural materials, the clearer it becomes that we can also learn a lot from nature on an industrial scale," Ille C. Gebeshuber is convinced. "In technology, we think of every object for a very specific purpose. In nature, on the other hand, everything almost always has more than one function. It’s not about optimizing certain material parameters, but also about optimizing resource and energy consumption, about the ability to repair and heal, about complex branched networks, not just about linear thinking." Gebeshuber is convinced that materials research will completely change our own approaches and habits in the future thanks to new findings from nature.