UK and Italian researchers just made spider silk three times stronger, and ten times tougher – thanks to an exciting nanotechnology boost with graphene.
They exposed three different spider species to water containing graphene – also known as carbon nanotubes – and then tested the enhanced silk. The bionic spider silk could be useful where light but very strong materials are required, including parachutes, they say.
The researchers, led by Professor Nicola Pugno at the University of Trento in Italy, say the discovery could pave the way for a new class of bionicomposites, with a wide variety of uses.
“Humans have used silkworm silks widely for thousands of years, but recently research has focussed on spider silk, as it has extremely promising mechanical properties,” Professor Pugno said.
“It is among the best spun polymer fibres in terms of tensile strength, ultimate strain, and especially toughness, even when compared to synthetic fibres such as Kevlar.”
Professor Pugno said we already know that there are biominerals present in in the protein matrices and hard tissues of insects – which gives them high strength and hardness in their jaws, mandibles and teeth, for example.
So this study looked at whether spider silk’s properties could be “enhanced” by artificially incorporating various different nanomaterials into the silk’s biological protein structures.
“We found that the strongest silk the spiders spun had a fracture strength up to 5.4 gigapascals (GPa), and a toughness modulus up to 1,570 joules per gram (J/g),” Professor Pugno said.
Normal spider silk, by comparison, has a fracture strength of around 1.5 GPa and a toughness modulus of around 150 J/g.
Professor Pugno said this is the highest fibre toughness discovered to date, and a strength comparable to that of the strongest carbon fibres or limpet teeth.
These silks’ high toughness and resistance to ultimate strain could have applications such as parachutes, and the whole process of the natural integration of reinforcements in biological structural materials could also be applied to other animals and plants – leading to a new class of “bionicomposites”.