Tag Archives: MXene

Lightweight nanomaterial for firefighters’ safety suits

This piece of research on firefighters’ safety suits comes from Australia’s Nuclear Science and Technology Organisation (ANSTO). A February 3, 2022 article by Judy Skatssoon for governmentnews.com.au describes the work, (Note: Despite the date of the article, the research is from 2021)

Researchers at ANSTO are developing a new highly protective nano-material they believe will produce light-weight safety suits that are perfect for Australian firefighters.

The technology involves the use of super-thin nanosheets made from a new fire and heat-resistant non-organic compound, thermo-hydraulics specialist Professor Guan Heng Yeoh says.

The compound is created from titanium carbide and produces a lightweight coating which can be used in place of traditional fire protection measures. 

A compound extracted from prawn shells, chitosan, is used to bind the nanomaterial together.

I found more details about the work in a January 25, 2022 ANSTO press release, Note: Links have been removed,

Scientists from UNSW [University of New South Wales] and ANSTO have characterised the structure of advanced materials, that could be used as a lightweight fire-retardant filler.

Fire retardant materials can self-extinguish if they ignite. 

A team under Professor Guan Heng Yeoh, Director of the ARC Training Centre for Fire Retardant Materials and Safety Technologies at UNSW and Thermal-Hydraulic Specialist at ANSTO, are working to commercialise advanced products for bushfire fighting, building protection and other applications.    

They investigated a family of two-dimensional transition metal carbides, carbonites and nitrides, known as MXenes.

In research published in Composites Part C, they reported the molecular structure of MXene, using neutron scattering and other advanced techniques.

Because the stability, properties, and various applications of MXene rely heavily on its atomic and molecular structure,  Prof Yeoh and associates conducted a detailed structural and surface characterisation of MXene.

Knowledge from this research provided good insight on how structure affects electrical, thermoelectric, magnetic and other properties of Mxene.

Experiments at ANSTO’s Australian Centre for Neutron Scattering on the Bilby small-angle neutron scattering (SANS) instrument were undertaken to characterise the two-dimensional structure of nanosheets—revealing the thickness of the material and the gaps between layers.

Theoretical modelling was used to extrapolate key information from the SANS data regarding the structural architecture of the titanium carbide nanosheets and investigate the influence of temperature on the structure.

Measurements revealed that MXene that is suspended in a colloidal solution consists of nanosheets of ultrathin multilayers with clear sharp edges.

The material comprises nanolayers, which overlap each other and form clusters of micro-sized units that endow a level of protection.

The nanolayers can be added on top of organic fire-retardant polymers. The total thickness of MXene was found to be 3 nm.

The information was in alignment with observations made using scanning electron microscopy and transmission electron microscopy.

Senior Instrument scientist Dr Jitendra Mata said, “Using SANS is like looking through a keyhole, the keyhole gives you a size indication from 1 nanometre to 500nm.  It may feel like a small size, but it’s actually not – many physical phenomena and the chemical structure occur within that size range.

“There are not many techniques in the world that gives you information about the structure and surface that accurately in a suspension and in films. Also, neutrons are ideal for many in-situ studies.”

Protective suits made with traditional retardant use as much as 30 to 40 per cent carbon compounds to achieve fire-retardant properties, which makes them heavy.

“Because we can use very low concentrations of the two-dimensional material, it comprises only about 1- 5 per cent of the total weight of the final material,” explained Prof Yeoh.

“And because it can be applied as a post-treatment, it doesn’t complicate the manufacturing process.”

When heat comes from above the surface of the material, it is conducted and moved along the nanosheets dispersing it. The nanosheets also act as a heat shield.

“At this point, it takes a lot of time to etch out the aluminium, but there are groups working on upscaling the MXene production process,” said Prof Yeoh.

“We also need to look at the performance and characteristics of the material at higher temperatures up to 800°C,” he added.

At the macro level, early tests have found the material to be an effective fire retardant.

A large team of researchers from the UNSW and ANSTO contributed to the research including first authors, Anthony Chun Yin Yuen and Timothy Bo Yuan Chen and ANSTO instrument scientist, Dr Andrew Whitten.

The versatile material could also potentially be used in energy storage devices.

Here’s a link to and a citation for the paper,

Study of structure morphology and layer thickness of Ti3C2 MXene with Small-Angle Neutron Scattering (SANS) by Anthony Chun Yin Yuen, Timothy Bo Yuan Chen, Bo Lin, Wei Yang, Imrana I.Kabir, Ivan Miguel De Cachinho Cordeiro, Andrew E.Whitten, Jitendra Mata, Bin Yu, Hong-Dian Lu. Guan Heng Yeoh. Composites Part C: Open Access Volume 5, July 2021, 100155 https://doi.org/10.1016/j.jcomc.2021.100155

This paper is open access.

2D materials for a computer’s artificial brain synapses

A January 28, 2022 news item on Nanowerk describes for some of the latest work on hardware that could enable neuromorphic (brainlike) computing. Note: A link has been removed,

Researchers from KTH Royal Institute of Technology [Sweden] and Stanford University [US] have fabricated a material for computer components that enable the commercial viability of computers that mimic the human brain (Advanced Functional Materials, “High-Speed Ionic Synaptic Memory Based on 2D Titanium Carbide MXene”).

A January 31, 2022 KTH Royal Institute of Technology press release (also on EurekAlert but published January 28, 2022), which originated the news item, delves further into the research,

Electrochemical random access (ECRAM) memory components made with 2D titanium carbide showed outstanding potential for complementing classical transistor technology, and contributing toward commercialization of powerful computers that are modeled after the brain’s neural network. Such neuromorphic computers can be thousands times more energy efficient than today’s computers.

These advances in computing are possible because of some fundamental differences from the classic computing architecture in use today, and the ECRAM, a component that acts as a sort of synaptic cell in an artificial neural network, says KTH Associate Professor Max Hamedi.

“Instead of transistors that are either on or off, and the need for information to be carried back and forth between the processor and memory—these new computers rely on components that can have multiple states, and perform in-memory computation,” Hamedi says.

The scientists at KTH and Stanford have focused on testing better materials for building an ECRAM, a component in which switching occurs by inserting ions into an oxidation channel, in a sense similar to our brain which also works with ions. What has been needed to make these chips commercially viable are materials that overcome the slow kinetics of metal oxides and the poor temperature stability of plastics.                   

The key material in the ECRAM units that the researchers fabricated is referred to as MXene—a two-dimensional (2D) compound, barely a few atoms thick, consisting of titanium carbide (Ti3C2Tx). The MXene combines the high speed of organic chemistry with the integration compatibility of inorganic materials in a single device operating at the nexus of electrochemistry and electronics, Hamedi says.

Co-author Professor Alberto Salleo at Stanford University, says that MXene ECRAMs combine the speed, linearity, write noise, switching energy, and endurance metrics essential for parallel acceleration of artificial neural networks.

“MXenes are an exciting materials family for this particular application as they combine the temperature stability needed for integration with conventional electronics with the availability of a vast composition space to optimize performance, Salleo says”

While there are many other barriers to overcome before consumers can buy their own neuromorphic computers, Hamedi says the 2D ECRAMs represent a breakthrough at least in the area of neuromorphic materials, potentially leading to artificial intelligence that can adapt to confusing input and nuance, the way the brain does with thousands time smaller energy consumption. This can also enable portable devices capable of much heavier computing tasks without having to rely on the cloud.

Here’s a link to and a citation for the paper,

High-Speed Ionic Synaptic Memory Based on 2D Titanium Carbide MXene by
Armantas Melianas, Min-A Kang, Armin VahidMohammadi, Tyler James Quill, Weiqian Tian, Yury Gogotsi, Alberto Salleo, Mahiar Max Hamedi. Advanced Functional Materials DOI: https://doi.org/10.1002/adfm.202109970 First published: 21 November 2021

This paper is open access.

MXene-coated yarn for wearable electronics

There’s been a lot of talk about wearable electronics, specifically e-textiles, but nothing seems to have entered the marketplace. Scaling up your lab discoveries for industrial production can be quite problematic. From an October 10, 2019 news item on ScienceDaily,

Producing functional fabrics that perform all the functions we want, while retaining the characteristics of fabric we’re accustomed to is no easy task.

Two groups of researchers at Drexel University — one, who is leading the development of industrial functional fabric production techniques, and the other, a pioneer in the study and application of one of the strongest, most electrically conductive super materials in use today — believe they have a solution.

They’ve improved a basic element of textiles: yarn. By adding technical capabilities to the fibers that give textiles their character, fit and feel, the team has shown that it can knit new functionality into fabrics without limiting their wearability.

An October 10, 2019 Drexel University news release (also on EurekAlert), which originated the news item, details the proposed solution (pun! as you’ll see in the video following this excerpt),

In a paper recently published in the journal Advanced Functional Materials, the researchers, led by Yury Gogotsi, PhD, Distinguished University and Bach professor in Drexel’s College of Engineering, and Genevieve Dion, an associate professor in Westphal College of Media Arts & Design and director of Drexel’s Center for Functional Fabrics, showed that they can create a highly conductive, durable yarn by coating standard cellulose-based yarns with a type of conductive two-dimensional material called MXene.

Hitting snags

“Current wearables utilize conventional batteries, which are bulky and uncomfortable, and can impose design limitations to the final product,” they write. “Therefore, the development of flexible, electrochemically and electromechanically active yarns, which can be engineered and knitted into full fabrics provide new and practical insights for the scalable production of textile-based devices.”

The team reported that its conductive yarn packs more conductive material into the fibers and can be knitted by a standard industrial knitting machine to produce a textile with top-notch electrical performance capabilities. This combination of ability and durability stands apart from the rest of the functional fabric field today.

Most attempts to turn textiles into wearable technology use stiff metallic fibers that alter the texture and physical behavior of the fabric. Other attempts to make conductive textiles using silver nanoparticles and graphene and other carbon materials raise environmental concerns and come up short on performance requirements. And the coating methods that are successfully able to apply enough material to a textile substrate to make it highly conductive also tend to make the yarns and fabrics too brittle to withstand normal wear and tear.

“Some of the biggest challenges in our field are developing innovative functional yarns at scale that are robust enough to be integrated into the textile manufacturing process and withstand washing,” Dion said. “We believe that demonstrating the manufacturability of any new conductive yarn during experimental stages is crucial. High electrical conductivity and electrochemical performance are important, but so are conductive yarns that can be produced by a simple and scalable process with suitable mechanical properties for textile integration. All must be taken into consideration for the successful development of the next-generation devices that can be worn like everyday garments.”

The winning combination

Dion has been a pioneer in the field of wearable technology, by drawing on her background on fashion and industrial design to produce new processes for creating fabrics with new technological capabilities. Her work has been recognized by the Department of Defense, which included Drexel, and Dion, in its Advanced Functional Fabrics of America effort to make the country a leader in the field.

She teamed with Gogotsi, who is a leading researcher in the area of two-dimensional conductive materials, to approach the challenge of making a conductive yarn that would hold up to knitting, wearing and washing.

Gogotsi’s group was part of the Drexel team that discovered highly conductive two-dimensional materials, called MXenes, in 2011 and have been exploring their exceptional properties and applications for them ever since. His group has shown that it can synthesize MXenes that mix with water to create inks and spray coatings without any additives or surfactants – a revelation that made them a natural candidate for making conductive yarn that could be used in functional fabrics. [Gogotsi’s work was featured here in a May 6, 2019 posting]

“Researchers have explored adding graphene and carbon nanotube coatings to yarn, our group has also looked at a number of carbon coatings in the past,” Gogotsi said. “But achieving the level of conductivity that we demonstrate with MXenes has not been possible until now. It is approaching the conductivity of silver nanowire-coated yarns, but the use of silver in the textile industry is severely limited due to its dissolution and harmful effect on the environment. Moreover, MXenes could be used to add electrical energy storage capability, sensing, electromagnetic interference shielding and many other useful properties to textiles.”

In its basic form, titanium carbide MXene looks like a black powder. But it is actually composed of flakes that are just a few atoms thick, which can be produced at various sizes. Larger flakes mean more surface area and greater conductivity, so the team found that it was possible to boost the performance of the yarn by infiltrating the individual fibers with smaller flakes and then coating the yarn itself with a layer of larger-flake MXene.

Putting it to the test

The team created the conductive yarns from three common, cellulose-based yarns: cotton, bamboo and linen. They applied the MXene material via dip-coating, which is a standard dyeing method, before testing them by knitting full fabrics on an industrial knitting machine – the kind used to make most of the sweaters and scarves you’ll see this fall.

Each type of yarn was knit into three different fabric swatches using three different stitch patterns – single jersey, half gauge and interlock – to ensure that they are durable enough to hold up in any textile from a tightly knit sweater to a loose-knit scarf.

“The ability to knit MXene-coated cellulose-based yarns with different stitch patterns allowed us to control the fabric properties, such as porosity and thickness for various applications,” the researchers write.

To put the new threads to the test in a technological application, the team knitted some touch-sensitive textiles – the sort that are being explored by Levi’s and Yves Saint Laurent as part of Google’s Project Jacquard.

Not only did the MXene-based conductive yarns hold up against the wear and tear of the industrial knitting machines, but the fabrics produced survived a battery of tests to prove its durability. Tugging, twisting, bending and – most importantly – washing, did not diminish the touch-sensing abilities of the yarn, the team reported – even after dozens of trips through the spin cycle.

Pushing forward

But the researchers suggest that the ultimate advantage of using MXene-coated conductive yarns to produce these special textiles is that all of the functionality can be seamlessly integrated into the textiles. So instead of having to add an external battery to power the wearable device, or wirelessly connect it to your smartphone, these energy storage devices and antennas would be made of fabric as well – an integration that, though literally seamed, is a much smoother way to incorporate the technology.

“Electrically conducting yarns are quintessential for wearable applications because they can be engineered to perform specific functions in a wide array of technologies,” they write.

Using conductive yarns also means that a wider variety of technological customization and innovations are possible via the knitting process. For example, “the performance of the knitted pressure sensor can be further improved in the future by changing the yarn type, stitch pattern, active material loading and the dielectric layer to result in higher capacitance changes,” according to the authors.

Dion’s team at the Center for Functional Fabrics is already putting this development to the test in a number of projects, including a collaboration with textile manufacturer Apex Mills – one of the leading producers of material for car seats and interiors. And Gogotsi suggests the next step for this work will be tuning the coating process to add just the right amount of conductive MXene material to the yarn for specific uses.

“With this MXene yarn, so many applications are possible,” Gogotsi said. “You can think about making car seats with it so the car knows the size and weight of the passenger to optimize safety settings; textile pressure sensors could be in sports apparel to monitor performance, or woven into carpets to help connected houses discern how many people are home – your imagination is the limit.”

Researchers have produced a video about their work,

Here’s a link to and a citation for the paper,

Knittable and Washable Multifunctional MXene‐Coated Cellulose Yarns by Simge Uzun, Shayan Seyedin, Amy L. Stoltzfus, Ariana S. Levitt, Mohamed Alhabeb, Mark Anayee, Christina J. Strobel, Joselito M. Razal, Genevieve Dion, Yury Gogotsi. Advanced Functional Materials DOI: https://doi.org/10.1002/adfm.201905015 First published: 05 September 2019

This paper is behind a paywall.