Researchers at NTNU have developed a brand new elastomer with unprecedented stiffness and toughness, impressed by spider silk.
Inspired by extraordinarily sturdy spider silk, researchers at Norwegian College of Science and Know-how (NTNU) have developed a brand new materials that defies beforehand seen trade-offs between toughness and stiffness.
The fabric is a sort of polymer often called an elastomer as a result of it has a rubber-like elasticity. The newly developed elastomer options molecules which have eight hydrogen bonds in a single repeat unit, and it’s these bonds that assist to evenly distribute stress placed on the fabric and make it so sturdy.
“The eight hydrogen bonds are the origin of the extraordinary mechanical properties,” says Zhiliang Zhang, professor of mechanics and supplies at NTNU’s Division of Structural Engineering. The fabric was developed at NTNU NanoLab and partially funded by the Analysis Council of Norway.
Substance that’s stiff and difficult
The thought to introduce the next than common variety of hydrogen bonds got here from nature. “Spider silk accommodates the identical sort of construction,” says Yizhi Zhuo, who developed the brand new materials as a part of his PhD and postdoc work. “We knew it might lead to very particular properties.”
Scientists have beforehand famous that spider silk – particularly dragline silk, which offers the spokes and outer rim of a spider’s net – is each exceptionally stiff and difficult.
Stiffness and toughness are distinct properties in engineering, and are sometimes in opposition. Stiff supplies can face up to a variety of stress earlier than deforming, whereas robust supplies can take up a variety of vitality earlier than they break. Glass, for instance, is stiff however not robust.
Till now, replicating the twin stiffness and toughness of spider silk in artificial elastomers has not been attainable. “With industrial supplies, if you wish to have greater stiffness, you might have decrease toughness. It’s a commerce off. You can not have each,” says Zhang.
The crew’s new elastomer options distinct laborious and smooth domains. After devising and making it, the crew used an atomic drive microscope – with a decision of fractions of a nanometre – to have a look at the underlying construction of the fabric, and observe the interface between the laborious and smooth areas.
They noticed that in addition to the eight hydrogen bonds distributing stress, the mismatch in stiffness between the laborious and smooth domains helped to dissipate vitality additional by encouraging any cracks to department off as a substitute of constant alongside a straight path. “You probably have a zig-zag, you create a big fracture floor and dissipate extra vitality, so you might have greater toughness,” says Zhang.
A future in versatile electronics?
Alongside its mechanical properties, the fabric is optically clear and analysis suggests it might even self-heal at temperatures greater than 80 °C. If manufacturing could be scaled up, the brand new materials might sooner or later be utilized in versatile electronics – significantly wearable units which might be extra inclined to wreck and breakages.
Zhang and his colleagues filed a patent for his or her materials in March, however they proceed to work on introducing different fascinating properties to it. The smooth domains of their materials are made up of a silicon-based polymer often called PDMS, however the researchers suspect they might enhance the mechanical properties even additional by experimenting with different substances.
They might additionally like to increase the fabric’s properties to incorporate anti-icing – stopping ice sticking to it at low temperatures – and anti-fouling – stopping aquatic organisms like mussels and algae attaching to it – so it may very well be utilized in excessive situations, such because the Arctic. “This materials is an effective start line, however we need to add another performance,” says Zhang.
Reference: “Concurrently Toughening and Stiffening Elastomers with Octuple Hydrogen Bonding” by Yizhi Zhuo, Zhijie Xia, Yuan Qi, Takashi Sumigawa, Jianyang Wu, Petr Šesták, Yinan Lu, Verner Håkonsen, Tong Li,Feng Wang, Wei Chen, Senbo Xiao, Rong Lengthy, Takayuki Kitamura, Liangbin Li, Jianying He and Zhiliang Zhang, 3 Could 2021, Superior Supplies.
The analysis was funded by Analysis Council of Norway grant numbers 255507 and 245963.
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