November 02, 2016

Diamond nanothread may become as ubiquitous as plastic for clothes, cars and space elevators

Queensland University of Technology Dr Haifei Zhan is leading a global effort to work out how many ways humanity can use a newly-invented material with enormous potential - diamond nanothread (DNT).

First created by Pennsylvania State University last year, one-dimensional DNT is similar to carbon nanotubes, hollow cylindrical tubes 10,000 times smaller than human hair, stronger than steel - but brittle.

"DNT, by comparison, is even thinner, incorporating kinks of hydrogen in the carbon's hollow structure, called Stone-Wale (SW) transformation defects, which I've discovered reduces brittleness and adds flexibility," said Dr Zhan, from QUT's School of Chemistry, Physics and Mechanical Engineering.

"That structure makes DNT a great candidate for a range of uses. It's possible DNT may become as ubiquitous as plastic [for manufacturing] in the future, used in everything from clothing to cars.

This is QUT's Dr Haifei Zhan with model of diamond nanothread. CREDIT Anthony Weate, QUT

Nanoscale - From brittle to ductile: a structure dependent ductility of diamond nanothread

Carbon - The morphology and temperature dependent tensile properties of diamond nanothreads

Advanced Functional Material - Diamond Nanothread as a New Reinforcement for Nanocomposites

Carbon - Thermal conductivity of a new carbon nanotube analog: The diamond nanothread

"That structure makes DNT a great candidate for a range of uses. It's possible DNT may become as ubiquitous a plastic in the future, used in everything from clothing to cars.

"I feel very lucky to have this chance to study a new material in depth - blue-sky applied research opportunities like this are rare."

DNT does not look like a rock diamond. Rather, its name refers to the way the carbon atoms are packed together, similar to diamond, giving it its phenomenal strength.

Dr Zhan has been modeling the properties of DNT since it was invented, using large-scale molecular dynamics simulations and high-performance computing.

He was the first to realize the SW defects were the key to DNT's versatility.

"While both carbon nanotubes and DNT have great potential, the more I model DNT properties, the more it looks to be a superior material," Dr Zhan said.

"The SW defects give DNT a flexibility that rigid carbon nanotubes can't replicate - think of it as the difference between sewing with uncooked spaghetti and cooked spaghetti.

"My simulations have shown that the SW defects act like hinges, connecting straight sections of DNT. And by changing the spacing of those defects, we can a change - or tune - the flexibility of the DNT."

That research is published in the peer-reviewed publication Nanoscale.

Dr Zhan has also published a number of other results from his DNT-modeling research:

  • The thermal conductivity of DNT can be tuned by changing the spacing between the SW defects (Carbon).
  • SW defects create irregular surfaces on the DNT, allowing it to bond well with polymers. DNT could therefore be used as reinforcement for nanocomposite materials (Advanced Function Materials).
  • The mechanical properties of DNT vary significantly depending on its exact atomic structure, including tensile behavior. Temperature also affects the mechanical properties. While DNT likely behaves like a flexible elastic rod, the mechanical properties could be tailored for specific purposes (Carbon).

"Further modeling is needed to fully investigate all the properties of DNT. However, I am excited about the potential range of applications it could be used for, given we've proven we can control its flexibility, conductivity and strength," Dr Zhang said.

"Carbon is the most abundant element on the planet. It's a renewable resource, so the cost of the raw material is extremely low.

"Once the manufacturing costs are viable, DNT would likely be used primarily in mechanical applications, combined with other materials to make ultra-strong, light-weight composites and components - such as plane fuselages.

"I plan to test how DNT performs as a two-dimensional networked structure - a sheet or layer - for potential use in flexible electronics and screens.

"I also want to test is viability as a fibre for textiles or rope, from bullet-proof vests and hard-wearing work gear to a replacement for steel cables in bridge construction.

"There's already talk in the global carbon community of DNT being the best candidate yet for building a space elevator. It would be a real honor if my research contributed to the development of DNTs for that purpose."

Abstract Nanoscale

As a potential building block for the next generation of devices/multifunctional materials that are spreading in almost every technology sector, one-dimensional (1D) carbon nanomaterial has received intensive research interests. Recently, a new ultra-thin diamond nanothread (DNT) has joined this palette, which is a 1D structure with poly-benzene sections connected by Stone–Wales (SW) transformation defects. Using large-scale molecular dynamics simulations, we found that this sp3 bonded DNT can transition from brittle to ductile behaviour by varying the length of the poly-benzene sections, suggesting that DNT possesses entirely different mechanical responses than other 1D carbon allotropes. Analogously, the SW defects behave like a grain boundary that interrupts the consistency of the poly-benzene sections. For a DNT with a fixed length, the yield strength fluctuates in the vicinity of a certain value and is independent of the “grain size”. On the other hand, both yield strength and yield strain show a clear dependence on the total length of DNT, which is due to the fact that the failure of the DNT is dominated by the SW defects. Its highly tunable ductility together with its ultra-light density and high Young's modulus makes diamond nanothread ideal for the creation of extremely strong three-dimensional nano-architectures.

Carbon Abstract

The ultrathin one-dimensional sp3 diamond nanothreads (NTHs), as successfully synthesised recently, have greatly augmented the interests from the carbon community. In principle, there can exist different stable NTH structures. In this work, we studied the mechanical behaviours of three representative NTHs using molecular dynamics simulations. It is found that the mechanical properties of NTH can vary significantly due to morphology differences, which are believed to originate from the different stress distributions determined by its structure. Further studies have shown that the temperature has a significant impact on the mechanical properties of the NTH. Specifically, the failure strength/strain decreases with increasing temperature, and the effective Young’s modulus appears independent of temperature. The remarkable reduction of the failure strength/strain is believed to be resulted from the increased bond re-arrangement process and free lateral vibration at high temperatures. In addition, the NTH is found to have a relatively high bending rigidity, and behaves more like flexible elastic rod. This study highlights the importance of structure-property relation and provides a fundamental understanding of the tensile behaviours of different NTHs, which should shed light on the design and also application of the NTH-based nanostructures as strain sensors and mechanical connectors.

Abstract - Advanced Functional Material

This work explores the application of a new one-dimensional carbon nanomaterial, the diamond nanothread (DNT), as a reinforcement for nanocomposites. Owing to the existence of Stone-Wales transformation defects, the DNT intrinsically possesses irregular surfaces, which is expected to enhance the non-covalent interfacial load transfer. Through a series of in silico pull-out studies of the DNT in polyethylene (PE) matrix, we found that the load transfer between DNT and PE matrix is dominated by the non-covalent interactions, in particular the van der Waals interactions. Although the hydrogenated surface of the DNT reduces the strength of the van der Waals interactions at the interface, the irregular surface of the DNT can compensate for the weak bonds. These factors lead to an interfacial shear strength of the DNT/PE interface comparable with that of the carbon nanotube (CNT)/PE interface. Our results show that the DNT/PE interfacial shear strength remains high even as the number of Stone-Wales transformation defects decreases. It can be enhanced further by increasing the PE density or introduction of functional groups to the DNT, both of which greatly increase the non-covalent interactions.

Abstract - Carbon - Thermal conductivity of a new carbon nanotube analog: The diamond nanothread

Based on the non-equilibrium molecular dynamics simulations, we have studied the thermal conductivities of a novel ultra-thin one-dimensional carbon nanomaterial – diamond nanothread (DNT). Unlike single-wall carbon nanotube (CNT), the existence of the Stone-Wales (SW) transformations in DNT endows it with richer thermal transport characteristics. There is a transition from wave-dominated to particle-dominated transport region, which depends on the length of poly-benzene rings. However, independent of the transport region, strong length dependence in thermal conductivity is observed in DNTs with different lengths of poly-benzene ring. The distinctive SW characteristic in DNT provides more to tune the thermal conductivity not found in the homogeneous structure of CNT. Therefore, DNT is an ideal platform to investigate various thermal transport mechanisms at the nanoscale. Its high tunability raises the potential to design DNTs for different applications, such as thermal connection and temperature management.

SOURCES- Carbon, Nanoscale, Queensland University of Technology,

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