Material Science News and Discussions

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Healable carbon fiber composite offers path to long-lasting, sustainable materials
https://phys.org/news/2021-11-healable- ... -path.html
by Andy Freeberg, University of Washington

Because of their high strength and light weight, carbon-fiber-based composite materials are gradually replacing metals for advancing all kinds of products and applications, from airplanes to wind turbines to golf clubs. But there's a trade-off. Once damaged or compromised, the most commonly-used carbon fiber materials are nearly impossible to repair or recycle.

In a paper posted this week in the journal Carbon, a research team that includes UW mechanical engineering Assistant Professor Aniruddh Vashisth describes a new type of carbon fiber reinforced material that is as strong and light as traditionally used ones but can be repeatedly healed with heat, reversing any fatigue damage and providing a way to break it down and recycle it when it reaches the end of its life.
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Quicker, more precise way to find metallic glasses

by Yale School of Engineering and Applied Science
https://phys.org/news/2021-11-quicker-p ... asses.html
Metallic glasses are being developed for a broad range of applications. The relatively new material is stronger than even the best metals, but with the pliability of plastic.

However, finding the right elements to make metallic glasses has proven a time-consuming task. A team of researchers, including Jan Schroers, professor of mechanical engineering & materials science, has devised a way to dramatically reduce the amount of time that it takes. Their results are published in Nature Materials.

Metallic glasses owe their properties to their unique atomic structures: when metallic glasses cool from a liquid to a solid, their atoms settle into a random arrangement and do not crystallize the way traditional metals do. But the glass-forming ability (GFA)—that is, how easy a metal or alloy can be turned into a glass—is complex and poorly understood. And trying to quantify the GFA of a material has been experimentally elaborate and computationally challenging. As a consequence, the ideal combination of properties has been found in only a few alloys, and current use of metallic glass is limited to highly specialized applications. To unleash their potential, a much wider range of alloys must be characterized.

The team of researchers has devised a method that takes much of the time and the trial-and-error out of the process. They found that with conventional X-ray diffraction, they could figure out how readily an alloy can be converted to glass. For the study, they processed about 5,700 X-ray diffraction patterns from 12 alloy systems—an unprecedented amount of experimental data, both in quantity and in consistent quality.
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Polymer discovery gives 3D-printed sand super strength
https://phys.org/news/2021-11-polymer-d ... super.html
by Oak Ridge National Laboratory
Researchers at the Department of Energy's Oak Ridge National Laboratory designed a novel polymer to bind and strengthen silica sand for binder jet additive manufacturing, a 3D-printing method used by industries for prototyping and part production.

The printable polymer enables sand structures with intricate geometries and exceptional strength—and is also water soluble.

The study, published in Nature Communications, demonstrates a 3D-printed sand bridge that at 6.5 centimeters can hold 300 times its own weight, a feat analogous to 12 Empire State Buildings sitting on the Brooklyn Bridge.

The binder jet printing process is cheaper and faster than other 3D-printing methods used by industry and makes it possible to create 3D structures from a variety of powdered materials, offering advantages in cost and scalability. The concept stems from inkjet printing, but instead of using ink, the printer head jets out a liquid polymer to bind a powdered material, such as sand, building up a 3D design layer by layer. The binding polymer is what gives the printed sand its strength.
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Synthetic biology yields easy-to-use underwater adhesives
https://phys.org/news/2021-11-synthetic ... water.html
by Brandie Jefferson, Washington University in St. Louis
Several marine organisms, such as mussels, secrete adhesive proteins that allow them to stick to different surfaces under sea water. This attractive underwater adhesion property has inspired decades of research to create biomimetic glues for underwater repair or biological tissue repair. However, existing glues often do not have the desirable adhesion, are hard to use underwater, or are not biocompatible for medical applications. Now, there is a solution from synthetic biology.

Researchers a the McKelvey School of Engineering at Washington University in St. Louis have developed a method that uses engineered microbes to produce the necessary ingredients for a biocompatible adhesive hydrogel that is as strong as spider silk and as adhesive as mussel foot protein (Mfp), which means it can stick to a myriad of surfaces underwater.

The research led by Fuzhong Zhang, professor of energy, environmental and chemical engineering, was published in the journal ACS Applied Materials and Interfaces.
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‘Super jelly’ can survive being run over by a car

25 Nov 2021

Researchers have developed a jelly-like material that can withstand the equivalent of an elephant standing on it, and completely recover to its original shape, even though it’s 80% water.

The soft-yet-strong material, developed by a team at the University of Cambridge, looks and feels like a squishy jelly, but acts like an ultra-hard, shatterproof glass when compressed, despite its high water content.

The non-water portion of the material is a network of polymers held together by reversible on/off interactions that control the material’s mechanical properties. This is the first time that such significant resistance to compression has been incorporated into a soft material.

The ‘super jelly’ could be used for a wide range of potential applications, including soft robotics, bioelectronics or even as a cartilage replacement for biomedical use. The results are reported in the journal Nature Materials.

https://www.cam.ac.uk/research/news/sup ... r-by-a-car


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Novel chemical design makes hard crystals stretchy
https://phys.org/news/2021-12-chemical- ... etchy.html
by Dartmouth College
Researchers have discovered a new way to make crystals stretchy, a modification that could enable them to act as very effective nanofilters.

"Picture a diamond that behaves like a rubber band," says Assistant Professor of Chemistry Chenfeng Ke. His research team has designed a new type of porous, carbon-based crystals that can stretch to more than twice their length.

Known to chemists as porous organic frameworks, these materials are typically hard. They are built from a scaffold of lightweight organic molecules like carbon, oxygen, and nitrogen. Additional molecular crosslinks are chemically stitched in to strengthen the structure. Their structures resemble open nets full of voids, or pores, that can house a variety of molecules as guests. This allows them to act as filters that can remove certain pollutants from air and water, or separate and store commercially important chemicals. The size of the pores usually determines which molecules can be absorbed and stored.

By tweaking the design of the molecular building blocks, the researchers have now made it possible for specific chemicals to make the crystal expand. It's as if some molecules have a key that can unlock a whole lot of extra space that they can now occupy, says Jayanta Samanta, a research associate in the Ke Functional Materials Group.
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Plant-based component could boost bacterial production of biodegradable plastic
https://phys.org/news/2021-12-plant-bas ... ction.html
by Scott Schrage, University of Nebraska-Lincoln
Given that less than 10 percent of synthetic plastics are recycled, the petroleum-derived, non-biodegradable materials continue to accumulate across the planet, covering stretches of land and the ocean floor. Microplastics have been found 29,000 feet above sea level, on the peak of Mount Everest, and 36,000 feet below it, in the depths of the Mariana Trench.

Some bacteria produce biodegradable plastics when deprived of nutrients or otherwise stressed, positioning them as part of a solution to the plastic pollution crisis. Unfortunately, the cost of feeding and maintaining those microbes has impeded efforts to scale up their production of biodegradable plastics. So researchers have set out to engineer microbes that yield bioplastics—especially poly-3-hydroxybutyrate, or PHB—faster, more efficiently and from renewable feedstocks.

Nebraska's Rajib Saha and colleagues have been studying the species Rhodopseudomonas palustris for secrets to engineering a better bacterium. Their recent experiments generated a bevy of important findings. Among them? A component of decomposed lignin—a polymer found in the cell walls of nearly all land-based plants—can substantially boost R. palustris production of PHB plastic.

To better understand why, the team turned to a model that maps the metabolic processes responsible for turning feedstocks into various products, including bioplastics. That model helped reveal multiple strategies for optimizing PHB production, from bypassing a biochemical reaction that normally acts as a bottleneck to growing the microbes on surfaces abundant in electrons and carbon atoms.
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New atomically thin material could improve efficiency of light-based tech
https://phys.org/news/2021-12-atomicall ... based.html
by Melissa Pappas, University of Pennsylvania

Solar panels, cameras, biosensors and fiber optics are technologies that rely on photodetectors, or sensors that convert light into electricity. Photodetectors are becoming more efficient and affordable, with their component semiconductor chips decreasing in size. However, this miniaturization is pushing against limits set by current materials and manufacturing methods, forcing trade-offs between size and performance.

There are many limitations of the traditional semiconductor chip manufacturing process. The chips are created by growing the semiconductor film over the top of a wafer in a way where the film's crystalline structure is in alignment with that of the substrate wafer. This makes it difficult to transfer the film to other substrate materials, reducing its applicability.

Additionally, the current method of transferring and stacking these films is done through mechanical exfoliation, a process where a piece of tape pulls off the semiconductor film and then transfers it to a new substrate, layer by layer. This process results in multiple non-uniform layers stacked upon one another with each layer's imperfections accumulated in the whole. This process affects the quality of the product as well as limits the reproducibility and scalability of these chips.
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New technique tunes into graphene nanoribbons' electronic potential
https://phys.org/news/2021-12-technique ... ronic.html
by Lawrence Berkeley National Laboratory
Ever since graphene—a thin carbon sheet just one-atom thick—was discovered more than 15 years ago, the wonder material became a workhorse in materials science research. From this body of work, other researchers learned that slicing graphene along the edge of its honeycomb lattice creates one-dimensional zigzag graphene strips or nanoribbons with exotic magnetic properties.

Many researchers have sought to harness nanoribbons' unusual magnetic behavior into carbon-based, spintronics devices that enable high-speed, low-power data storage and information processing technologies by encoding data through electron spin instead of charge. But because zigzag nanoribbons are highly reactive, researchers have grappled with how to observe and channel their exotic properties into a real-world device.

Now, as reported in the Dec. 22 issue of the journal Nature, researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley have developed a method to stabilize the edges of graphene nanoribbons and directly measure their unique magnetic properties.

The team co-led by Felix Fischer and Steven Louie, both faculty scientists in Berkeley Lab's Materials Sciences Division, found that by substituting some of the carbon atoms along the ribbon's zigzag edges with nitrogen atoms, they could discretely tune the local electronic structure without disrupting the magnetic properties. This subtle structural change further enabled the development of a scanning probe microscopy technique for measuring the material's local magnetism at the atomic scale.
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Sustainable silk material for biomedical, optical, food supply applications
https://phys.org/news/2022-01-sustainab ... tical.html
by American Institute of Physics
While silk is best known as a component in clothes and fabric, the material has plentiful uses, spanning biomedicine to environmental science. In Applied Physics Reviews, researchers from Tufts University discuss the properties of silk and recent and future applications of the material.

Silk makes an important biomaterial, because it does not generate an immune response in humans and promotes the growth of cells. It has been used in drug delivery, and because the material is flexible and has favorable technological properties, it is ideal for wearable and implantable health monitoring sensors.

As an optically transparent and easily manipulated material at the nano- and microscale, silk is also useful in optics and electronics. It is used to develop diffractive optics, photonic crystals, and waveguides, among other devices.

More recently, silk has come to the forefront of sustainability research. The material is made in nature and can be reprocessed from recycled or discarded clothing and other textiles. The use of silk coatings may also reduce food waste, which is a significant component of the global carbon footprint.
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