Category: Chemistry

A team of researchers at the Chinese Academy of Sciences, working with a colleague from the State University of New Jersey, has developed a gel-based code-hiding system that uses combinations of water, light and heat to hide and reveal hidden codes. In their paper published in the journal Science Advances, the group describes how their gel is made and the possible uses for it.

A variety of techniques are used to keep sensitive information safe from prying eyes—requiring passcodes before gaining access to a bank account, for example. Other techniques are required to prevent counterfeiting of sensitive documents, such as passports or paper money. Currently, most methods that have been developed to prevent counterfeiting involve adding an attribute to the material to be protected—a watermark, for example, that glows under a UV light. In this new effort, the researchers developed a new means for preventing counterfeiting that can also be used to convey passcodes.

The work involved manipulating types of molecules called donor-acceptor Stenhouse adducts (DASAs)—they change from a given color to transparent when exposed to normal light. The researchers created 12 molecules that change from reflecting colors to transparency when exposed to certain combinations of water, light and heat. By allowing for mixing up the amount of each that are used, the three ingredients represent a cypher of sorts. To use such a cypher, the researchers embedded the molecules in a polymer.

In practice, a person would choose desired ratios of light, water and heat and then use the gel as a sort of ink to print number codes onto a piece of paper in the format of numbers displayed on a digital clock. Each of the segments making up a number would have different amounts of DASAs. The ratios would then be divulged only to those people who are supposed to have access to the code.

Such a system could be used to verify the authenticity of documents such as passports or cash money. It could also be used to convey passcodes. Banks, for example, could securely send passwords to customers via printed documents. The researchers suggest their gel could prove useful in a wide variety of applications because it would be difficult to mimic the conditions needed to access the hidden data.

More information: Yu Dong et al, Harnessing molecular isomerization in polymer gels for sequential logic encryption and anticounterfeiting, Science Advances (2022). DOI: 10.1126/sciadv.add1980

Journal information: Science Advances 

Rotary molecular motors were first created in 1999, in the laboratory of Ben Feringa, Professor of Organic Chemistry at the University of Groningen. These motors are driven by light. For many reasons, it would be good to be able to make these motor molecules visible. The best way to do this is to make them fluoresce. However, combining two light-mediated functions in a single molecule is quite challenging. The Feringa laboratory has now succeeded in doing just that, in two different ways. These two types of fluorescing light-driven rotary motors were described in Nature Communications (September 30) and Science Advances (November 4).

“After the successful design of molecular motors in the past decades, an important next goal was to control various functions and properties using such motors,” explains Feringa, who shared in the Nobel Prize in Chemistry in 2016. “As these are light-powered rotary motors, it is particularly challenging to design a system that would have another function that is controlled by light energy, in addition to the rotary motion.”

Feringa and his team were particularly interested in fluorescence since this is a prime technique that is widely used for detection, for example in biomedical imaging. Usually, two such photochemical events are incompatible in the same molecule; either the light-driven motor operates and there is no fluorescence or there is fluorescence and the motor does not operate. Feringa says, “We have now demonstrated that both functions can exist in parallel in the same molecular system, which is rather unique.”

Ryojun Toyoda, a postdoctoral researcher in the Feringa group, who now holds a professor position at Tohoku University in Japan, added a fluorescent dye to a classic Feringa rotary motor. “The trick was to prevent these two functionalities from blocking each other,” says Toyoda. He managed to quench the direct interactions between the dye and the motor. This was done by positioning the dye perpendicular to the upper part of the motor to which it was attached. “This limits the interaction,” Toyoda explains.

Different colors

In this way, the fluorescence and the rotary function of the motor can coexist. Furthermore, it turned out that changing the solvent allows him to tune the system: “By varying the solvent polarity, the balance between both functions can be changed.” This means that the motor has become sensitive to its environment, which could point the way for future applications.

Co-author Shirin Faraji, professor of Theoretical Chemistry at the university of Groningen, helped to explain how this happens. Kiana Moghaddam, a postdoc in her group, performed extensive quantum mechanical calculations and demonstrated how the key energetics governing the photo-excited dynamics strongly depend on the solvent polarity.

Another useful property of this fluorescing motor molecule is that different dyes could be attached to it as long as they have a similar structure. “So, it is relatively easy to create motors that are glowing in different colors,” says Toyoda.

Antenna

A second fluorescent motor was constructed by Lukas Pfeifer, also while working as a postdoctoral researcher in the Feringa group. He has since joined the École Polytechnique Fédérale in Lausanne, Switzerland: “My solution was based on a motor molecule that I had already made, which is driven by two low-energy near-infrared photons.” Motors that are powered by near-infrared light are useful in biological systems, as this light penetrates deeper into tissue than visible light and is less harmful to the tissue than UV light.

“I added an antenna to the motor molecule that collects the energy of two infrared photons and transfers it to the motor. While working on this, we discovered that with some modifications, the antenna could also cause fluorescence,” says Pfeifer. It turned out that the molecule can have two different excited states: in one state, the energy is transferred to the motor part and drives rotation, while the other state causes the molecule to fluoresce.

Power

“In the case of this second motor, the entire molecule fluoresces,” explains Professor Maxim Pshenichnikov, who performed spectroscopic analysis of both types of fluorescent motor and who is a co-author of both papers. “This motor is one chemical entity on which the wave function is not localized and, depending on the energy level, can have two different effects. By altering the wavelength of the light, and thus the energy that the molecule receives, you get either rotation or fluorescence.” Faraji adds, “Our synergized in-principle and in-practice approach highlights the interplay between theoretical and experimental studies, and it illustrates the power of such combined efforts.”

Now that the team has combined both motion and fluorescence in the same molecule, a next step would be to show motility and detect the molecule’s location simultaneously by tracing the fluorescence. Feringa says, “This is very powerful and we might apply it to show how these motors might traverse a cell membrane or move inside a cell, as fluorescence is a widely used technique to show where molecules are in cells. We could also use it to trace the movement that is induced by the light-powered motor, for instance on a nanoscale trajectory or perhaps trace motor-induced transport on the nanoscale. This is all part of follow-up research.”

More information: Ryojun Toyoda et al, Synergistic interplay between photoisomerization and photoluminescence in a light-driven rotary molecular motor, Nature Communications (2022). DOI: 10.1038/s41467-022-33177-0

Lukas Pfeifer et al, Dual Function Artificial Molecular Motors Performing Rotation and Photoluminescence, Science Advances (2022). DOI: 10.1126/sciadv.add0410. www.science.org/doi/10.1126/sciadv.add0410

Journal information: Science Advances  , Nature Communications 

Provided by University of Groningen 

Physicists at the Ural Federal University (UrFU) have created a theory for the solidification of iron-nickel (Fe-Ni) alloy (invar). They determined that an important role in the technology of creating invar products, namely in the solidification process, is played by the oncoming flow: when an alloy cools, the liquid layer flows on top of the solidified layer. If this process is regulated, it is possible to control the characteristics of the alloys, obtain a more uniform structure, and improve the properties of the final product.

Nickel and iron alloys are used to create high-precision instruments, including clocks, seismic sensors, chip substrates, valves and engines in aircraft structures, and instruments for telescopes. The right calculations will help to create an alloy of the required structure, which will affect the quality of the finished products. A description of the model and the behavior of melts, as well as analytical calculations, was published in the journal Scientific Reports.

“Let me explain the work with the help of an analogy. When the water freezes, it pushes out all the dirt. So you can take a piece of ice in your mouth, it will be clean. Approximately the same happens with melts during cooling. Only they do not push out all the impurities, but some of them. Some of the impurities come out and some remain in the melt.”

“What remains in the melt fills the gaps between the crystals that solidify and the voids that remain. Thus, the alloys are heterogeneous: one tiny piece is enriched, while the neighboring piece is not. And it affects the properties of the finished product,” says Dmitri Alexandrov, Head of the Ural Federal University’s Laboratory of Multi-Scale Mathematical Modeling.

The main thing that scientists have shown is the processes in a two-phase layer: a layer in which both solid and liquid phases are located, inside it there is a transformation from a liquid state to a solid one.

“This layer completely changes the crystallization scenario. Thus, for example, the temperature at each point of this layer is lower than the crystallization temperature, and crystallites and dendrites release the heat of phase transformation and thus partially compensate for supercooling.”

“In addition, the growing solid phase displaces the dissolved impurity, which lowers the crystallization temperature. These processes lead to the formation of complex branched structures of the solid phase, the gaps between which are filled by a liquid with a higher concentration of impurities,” says Liubov Toropova, senior researcher at the Laboratory of Mathematical Modeling of Physical and Chemical Processes at UrFU.

The name “invar” comes from the word “unchanging,” as the alloy almost does not expand or contract when the temperature changes. The first invar alloy was discovered by Swiss scientist Charles Edouard Guillaume in 1896. In 1920 he received the Nobel Prize in Physics for it.

This alloy of nickel and iron is used when a serious dimensional stability of finished parts is required: in precision instruments, clocks, valves, etc. One of the first applications of invar is rods for pendulum clocks. At the time when the pendulum clock was invented, it was the most precise chronometer in the world. Today, invar is also used in astronomy, as components that support the size-sensitive optics of astronomical telescopes.

More information: Dmitri V. Alexandrov et al, The role of incoming flow on crystallization of undercooled liquids with a two-phase layer, Scientific Reports (2022). DOI: 10.1038/s41598-022-22786-w

Journal information: Scientific Reports 

Provided by Ural Federal University 

In recent years, many engineers and material scientists have been trying to develop sustainable energy solutions that could help to mitigate climate change on Earth. This includes carbon capture technologies, which are specifically designed to capture or absorb carbon dioxide (CO₂) in sites where it is widely produced, such as power generation plants or industrial facilities that rely on biomass or burning fossil fuels.

While some carbon capture solutions achieved promising results, those based on conventional wet chemical scrubbing methods utilizing sp³ amines often consume too much energy and are prone to corrosion and sorbent degradation. This significantly limits their widespread implementation, highlighting the need for alternative CO₂ separation strategies.

Researchers at Johns Hopkins University, the University of Texas at Austin and Massachusetts Institute of Technology (MIT) have recently introduced a series of redox-tunable Lewis bases (i.e., molecules with a lone pair of electrons that can be donated to a coordinate covalent bond) with sp² nitrogen centers that can reversibly capture and release CO₂. In their paper, published in Nature Energy, they also outline strategies to fine-tune the properties of these Lewis bases.

“We demonstrate a library of redox-tunable Lewis bases with sp²-nitrogen centers that can reversibly capture and release carbon dioxide through an electrochemical cycle,” Xing Li, Xunhua Zhao, Yuanyue Liu, T. Alan Hatton and Yayuan Liu wrote in their paper. “The mechanism of the carbon capture process is elucidated via a combined experimental and computational approach.”

The researchers’ recent work is based on the idea that due to their CO₂ affinity, Lewis bases with redox-active sp² nitrogen centers could be modulated using electrochemical potentials, enabling the development of alternative, more effective carbon capture solutions. To verify this hypothesis, the researchers compiled a library of organic bases containing sp² nitrogen centers, including pyradine, diazine, thiadizole and azo moieties.

“While in the oxidized form, none of these compounds shows strong interactions with CO₂,” the researchers wrote in their paper. “However, their electro-reduction and subsequent oxidation behavior can be drastically modulated by the presence of CO₂ in the electrolyte.”

Li and his colleagues clearly outlined the mechanism that allows the Lewis base sorbents to capture carbon in both computational simulations and experiments. Subsequently, they showed that the properties of these sorbents can be fine-tuned (i.e., tailored for specific uses) using both molecular design and electrolyte engineering methods. By fine-tuning the properties of the Lewis bases they created, the researchers were then able to identify a particularly promising Lewis base based on bifunctional azopyridine.

“We identify a bifunctional azopyridine base that holds promise for electrochemically mediated carbon capture, exhibiting >85% capacity utilization efficiency over cycling in a flow system under 15% carbon dioxide with 5% oxygen,” Li and his colleagues wrote in their paper. “This work broadens the structural scope of redox-active carbon dioxide sorbents and provides design guidelines on molecules with tunable basicity under electrochemical conditions.”

In the future, the bifunctional azopyridine base identified by Li and his colleagues could be used to create more energy-efficient and effective carbon capture technologies. In addition, their work could pave the way towards the development of other carbon capture solutions based on Lewis base sorbents.

More information: Xing Li et al, Redox-tunable Lewis bases for electrochemical carbon dioxide capture, Nature Energy (2022). DOI: 10.1038/s41560-022-01137-z

Journal information: Nature Energy 

© 2022 Science X Network

Could the future of data storage be DNA? It’s the original format after all, storing the information needed to build every living thing.

And it has a handful of qualities that would make it perfect for storing all the digital information in our world.

With recent advances in sequencing and printing DNA, it’s technically possible, but there are a few obstacles to overcome before this sci-fi-sounding tech can become a household reality.

Provided by American Chemical Society 

Polymers are lightweight, durable, and easily processed into fabricated parts, features that promoted polymers to become the most relevant class of engineering materials by volume. However, recycling polymers is a challenge that materials scientists have been researching for decades.

An alternate route toward a more sustainable polymer industry is to increase the service lifetime of polymers. An intriguing new concept is to impart the ability to “self-heal” from structural damage. Michael Bockstaller, professor of materials science and engineering at Carnegie Mellon University Materials Science and Engineering, in collaboration with Krzysztof Matyjaszewski, professor of chemistry, has discovered that the binding of copolymers on the surface of nanoparticles that are already used in industrial manufacturing provides an economic and scalable route toward self-healing polymers with increased strength and toughness.

Normally when you think of the building blocks of materials, you think of atoms. In Bockstaller’s research group, this concept inspired a new approach to fabricate functional materials by assembling nanoparticle building blocks using a form of atom transfer radical polymerization, a technique invented and developed by Matyjaszewski. The properties of the resulting materials can be varied by controlling the interactions between nanoparticle building blocks. This concept opens up new possibilities to vary properties of engineering materials without having to change their chemical composition—a feature that is highly beneficial in the context of recyclability.

While working to make these particles more amenable to fabrication technologies like additive manufacturing, Bockstaller’s team experimented with putting copolymers at the surface of nanoparticles.

“If we can put polymers on the surface of nanoparticles, we can improve the interactions between them and make materials more mechanically robust and easier to form,” Bockstaller said.

Matyjaszewski added, “This work illustrates how controlling macromolecular architecture can dramatically enhance properties of various advanced materials.”

Copolymers are a special class of polymers that are made up of two different monomers and exhibit self-healing properties. The researchers found that when copolymers were added onto the surface of nanoparticles, new structures were formed that enhanced the polymer’s self-healing properties. This discovery is foundational to improving the recyclability of polymers.

“This enables us to avoid material failure,” Bockstaller explained. “If the material can self-heal, we reduce the need to discard materials damaged by stress.”

Bockstaller’s group will continue to explore strategies to maximize strength and toughness of copolymer-based self-healing materials and to make them available to scalable production methods.

This research was published in Macromolecules.

More information: Yuqi Zhao et al, Topologically Induced Heterogeneity in Gradient Copolymer Brush Particle Materials, Macromolecules (2022). DOI: 10.1021/acs.macromol.2c01131

Provided by Carnegie Mellon University Materials Science and Engineering

Dr. Emily Pentzer, associate professor in the Department of Materials Science and Engineering and the Department of Chemistry at Texas A&M University, is making 3D-printed polymers more environmentally friendly through a process that allows the polymers to naturally degrade over time. Pentzer’s research is a collaborative effort that includes researchers from the Texas A&M College of Engineering, the Texas A&M Engineering Experiment Station, the Texas A&M Department of Chemistry and the University of Kashmir.

The research was published in the journal Angewandte Chemie.

“Our goal was to create sustainable degradable polymeric structures,” Pentzer said. “We did this by leveraging the microstructures afforded by chemistry in conjunction with the macrostructures afforded by 3D printing.”

Most commercial synthetic polymers consist of large molecules that do not break apart under normal conditions. When left in the environment, manufactured items such as Styrofoam cups or plastic containers break down into small pieces that are unseen by the naked eye, but the long polymer molecules remain present forever.

“It’s not just the plastic bottle being kicked down the road,” Pentzer said. “These materials break down into microplastics that stay in the environment. We don’t fully understand the impact of microplastics, but they’ve been shown to carry diseases, heavy metals and fecal bacteria.”

To make the degradable polymers Pentzer collaborated with Dr. Don Darensbourg, distinguished professor in the Department of Chemistry at Texas A&M, to use carbon dioxide and table salt to create the ink that was used in the 3D printing process. After printing, the structures are washed with water to dissolve the salt and solidify the structure. While the outside of the structure continues to look smooth, the process creates thousands of small pores which allow the chemical compounds to degrade at a quicker rate.

“Under the right conditions, the polymers we’ve created will actually degrade quickly,” Pentzer said. “Ideally, they’ll break apart into small molecules that are not toxic. These smaller molecules won’t be able to carry things like heavy metals or bacteria.”

As the research progresses, Pentzer hopes to use this process to create packaging materials so that things like boxes and tape can degrade quickly rather than sitting in a landfill for years to come. She also sees a bright future for 3D-printed polymers in the biomedical field.

“These materials can be used for diverse biomedical applications,” Pentzer said. “Things like scaffolds for implants that will degrade over time so your body can heal, but you won’t have that piece of plastic in you forever.”

Through her interdisciplinary research, Pentzer is seeking to solve a worldwide problem that could have implications on the environment, human health, biomedicine and almost every aspect of human existence.

“It’s kind of like marrying the science with the engineering,” Pentzer said. “Working together, we can create synergy and achieve much more.”

More information: Peiran Wei et al, 3D Printed CO 2 ‐Based Triblock Copolymers and Post‐Printing Modification, Angewandte Chemie International Edition (2022). DOI: 10.1002/anie.202208355

Journal information: Angewandte Chemie International Edition  , Angewandte Chemie 

Provided by Texas A&M University College of Engineering 

When you cut yourself, a mass migration begins inside your body: Skin cells flood by the thousands toward the site of the wound, where they will soon lay down fresh layers of protective tissue.

In a new study, researchers from the University of Colorado Boulder have taken an important step toward unraveling the drivers behind this collective behavior. The team has developed an equation learning technique that might one day help scientists grasp how the body rebuilds skin, and could potentially inspire new therapies to accelerate wound healing.

“Learning the rules for how individual cells respond to the proximity and relative motion of other cells is critical to understanding why cells migrate into a wound,” said David Bortz, professor of applied mathematics at CU Boulder and senior author of the new study.

The research is the latest in a decade-long collaboration between Bortz and Xuedong Liu, professor of biochemistry at CU Boulder. The group’s method, called the Weak form Sparse Identification of Nonlinear Dynamics (WSINDy), can apply to a wide range of phenomena in the natural world, said study lead author Dan Messenger.

“While this paper is about cells, the math is also applicable to a wide range of fields, including how flocks of birds avoid both predators and each other,” said Messenger, a postdoctoral researcher in Bortz’s lab.

He and his colleagues published their results Oct. 12 in the Journal of The Royal Society Interface.

The research hinges on a set of tools from the field of “data-driven modeling,” an emerging area at the intersection of applied math, statistics and data science. Using this approach, the group designed computer simulations of hundreds of cells moving toward an artificial wound, then built a method to learn the equations to describe and examine the motion of each individual cell. The team’s tools are potentially much faster and more accurate than traditional modeling approaches—a boon for understanding complex natural phenomena like wound healing.

“To prevent infections, we want our wounds to close as soon as possible,” Liu said. “We plan to use these learned models to test pharmaceuticals and drug regimens that might be able to stimulate wound healing.”

Trial and error

Mathematical models come in a lot of shapes and sizes, but most use a complex series of equations to try to capture some phenomenon in the real world.

Bortz, for example, joined a team of scientists in 2020 who drew on models to try to predict the spread of COVID-19 in Colorado. But, he noted, it can take a lot of trial and error, and even supercomputers, to validate those equations.

“Developing an accurate and reliable model can be a very long and laborious process,” Bortz said.

In this new study, he and his colleagues extended their recently-developed WSINDy method to directly use data to learn models of individuals.

“It’s about putting the data first and letting the mathematics follow,” Bortz said.

Cells to particles

In the current study, he and his colleagues, including biochemistry graduate student Graycen Wheeler, decided to turn that data-driven lens to the problem of cell migration.

Liu and his colleagues have observed how skin cells surge together as a group in the lab. Migrating skin cells, they found, tend to follow certain rules: Like a herd of stampeding buffalo, skin cells will align their direction to the cells in front of them but also try not to bump into the leaders from behind.

To see if WSINDy could shed light on this mass movement, Bortz and Messenger designed computer simulations showing hundreds of digital cells moving in tandem. The team deployed their WSINDy approach to build precise equations describing the motion of each and every one of those cells.

“With WSINDy, if you have 1,000 cells, you can learn 1,000 different models,” Bortz said.

They then drew on even more math to begin clustering those models together. Bortz noted that WSINDy is especially well-suited to finding the patterns hiding in data. When the researchers, for example, mixed together two or more types of cells that moved in different ways, their suite of tools could accurately spot and sort the cells into groups.

“We not only learn models for each cell, but those models can be sorted, thus revealing the dominant categories of cell behaviors that play a role in wound healing,” Messenger said.

Moving forward, the collaborators hope to use their approach to start digging into the behavior of real cells in the lab. Liu noted that the technique could be especially useful for studying cancer. Cancer cells, he said, undergo similar mass migrations when they spread from one organ to another.

“As biochemists, we usually don’t have a quantitative way to describe this cell migration,” Liu said. “But now, we do.”

A team of researchers at Shanghai Jiao Tong University, working with a pair of colleagues from Harvard University, has developed a new way to synthesize single quantum nanomagnets that are based on metal-free, multi-porphyrin systems. In their paper published in the journal Nature Chemistry, the group describes their method and possible uses for it.

Molecular magnets are materials that are capable of exhibiting ferromagnetism. They are different from other magnets because their building blocks are composed of organic molecules or a combination of coordination compounds. Chemists have been studying their properties with the goal of using them to develop medical therapies such advanced magnetic resonance imaging, new kinds of chemotherapy and possibly magnetic-field-induced local hyperthermia therapy. In this new effort, the researchers have developed a way to create molecular nanomagnets with quantum properties.

The technique involved first synthesizing a monoporphyrin using what they describe as conventional “solution chemistry”—the monoporhyrins were created by using an atomic-force microscope to pull hydrogen atoms off of polyporphyrins. The researchers then applied the result to a base of gold, which they placed in an oven and heated to 80 °C. This forced the rings in the material to become chained. They then turned the oven up to 290°C and then let the material cook for another 10 minutes. This resulted in the formation of additional carbon cycles and the creation of quantum nanomagnets.

The technique works because it involves the use of porphyrins, which are heterocyclic molecules that have multiple double-bonds with delocalized electrons. They typically exist as rings. They also easily form complexes with ions and rare earth metals, which allows them to be used to create molecular magnets.

Once their magnets were complete, the researchers studied them using a scanning-tunneling microscope, finding ferromagnetic interactions between spins of 15 millielectronvolts. They further confirmed the existence of magnetic interaction exchange using spectroscopy with spin circulation.

The researchers suggest their approach is a relatively easy way to make polyporphyrin quantum nanomagnets of variable lengths, which can also have differing numbers of radical centers.

A new method to ensure consistency and quality in rubber manufacturing, developed by a research team from the University of Tennessee, Knoxville, and Eastman, is likely to show real-world impact on material sustainability and durability for products such as car tires.

As consumers in the U.S. and around the globe are increasingly incentivized toward electric vehicles and away from fossil-fuel reliance, current EV users have uncovered an unexpected maintenance issue. Due to the combination of higher weight and higher torque, EVs put more pressure on standard tires, causing them to degrade 30% faster than tires on internal-combustion vehicles.

UT’s Fred N. Peebles Professor and IAMM Chair of Excellence Dayakar Penumadu, along with electrical engineering graduate student Jun-Cheng Chin, postdoctoral researcher Stephen Young and three Eastman scientists, recently published research aimed at resolving one of rubber manufacturing’s most common challenges: identifying flaws in the material.

Rubber contains additives such as zinc oxide and sulfur that work to improve strength, elasticity and other favorable traits. When the ingredients are not distributed evenly throughout a rubber product such as a car tire, the material will contain flaws that cause the product to degrade prematurely.

“If components such as sulfur do not disperse well, that generates localized hard spots,” said Penumadu. “That hard stuff attracts a lot of mechanical and thermal stresses, making the material degrade prematurely.”

Even a flaw the width of a human hair can decrease the life span of a large rubber component such as a car tire.

“That leads to safety and economic impacts,” Penumadu said.

Identifying and studying such flaws—a field known as fracture mechanics—is critical to understanding how the material will perform. Yet finding such flaws before they cause problems is an issue that has long plagued the rubber industry.

“The current industry approach is to cut out a small sample of rubber, then observe it under an optical microscope,” Penumadu said. “Not only is this tedious and destructive, it’s unreliable. It requires you to guess beforehand where, in an opaque sample, you need to check for inconsistencies.”

In addition, optical microscopes cannot differentiate between rubber components—for example, sulfur and zinc oxide both appear as white specks.

Penumadu’s team has overcome this issue by switching from optical analysis to X-ray computed tomography. X-rays that pass through the sample are scattered and absorbed differently depending on the materials they strike. A computer then reconstructs a digital 3D model of the rubber’s interior.

“This is a very important point,” Penumadu said. “XCT lets us see the inside of the material noninvasively, and we can actually see the distribution of each component.”

The application of this new method increases the rubber industry’s ability to view and predict flaws and will ultimately lead to more consistent quality and longer-lasting rubber products.

In October the team received the 2021 Publication Excellence Award from the Journal of Rubber Chemistry and Technology for their groundbreaking paper, “Sulfur Dispersion Quantitative Analysis in Elastomeric Tire Formulations by Using High Resolution X-Ray Computed Tomography”, which discusses the new XCT method and their research findings.