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Chemistry

Polymers with Flawed Fillers: A Surprising Boost in Heat Transfer

In the quest to design the next generation of materials for modern devices — ones that are lightweight, flexible and excellent at dissipating heat — a team of researchers made a discovery: imperfection has its upsides.

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Polymers with Flawed Fillers: A Surprising Boost in Heat Transfer

In the quest for designing next-generation materials that are lightweight, flexible, and excellent at dissipating heat, researchers have made a groundbreaking discovery. Imperfections, it turns out, can be beneficial.

A study published in Science Advances found that polymers (commonly referred to as plastics) made with thermally conductive fillers containing defects performed 160% better than those with perfect fillers. This counterintuitive finding challenges long-held assumptions and points to a promising new strategy for engineering polymer composites with ultrahigh thermal conductivity.

The study was led by the University of Massachusetts Amherst, in collaboration with researchers from other top institutions. Polymers have revolutionized modern devices due to their unmatched lightness, electrical insulation, flexibility, and ease of processing. However, common polymers are thermal insulators with low thermal conductivity, which can lead to overheating issues.

For years, scientists have attempted to enhance the thermal conductivity of polymers by incorporating highly thermally conductive fillers such as metals, ceramics, or carbon-based materials. The logic is straightforward: blending in thermally conductive fillers should improve overall performance.

However, in practice, it’s not that simple. Consider a polymer blended with diamonds, which have an exceptional thermal conductivity of about 2,000 watts per meter per kelvin (W m-1 K-1). A polymer composed of 40% diamond filler might theoretically achieve conductivity of around 800 W m-1 K-1. Yet, practical results have fallen short due to challenges like filler clumping, defects, high contact resistance between polymers and fillers, and low thermal conductivity of polymer matrices.

Understanding thermal transport mechanisms in polymeric materials has been a long-standing challenge. The study aimed to lay the foundation for understanding thermal transport in polymeric materials and controlling heat transfer across heterogeneous interfaces.

The researchers created two polymer composites of polyvinyl alcohol (PVA) – one incorporating perfect graphite fillers and the other using defective graphite oxide fillers, each at a low 5% volume fraction. As expected, the perfect fillers on their own were more thermally conductive than imperfect ones.

However, surprisingly, when these fillers are added into polymers, polymers made with graphite oxide fillers containing defects performed 160% better than those with perfect graphite fillers. The team used a combination of experiments and models to study how defects influence thermal transport in polymer composites.

They found that defective fillers facilitate more efficient heat transfer because their uneven surfaces don’t allow the polymer chains to pack together as tightly as the perfectly smooth fillers do. This unexpected effect, known as enhanced vibrational couplings between the polymers and defective fillers at the polymer/filler interfaces, boosts thermal conductivity and reduces resistance.

“Defects, at times, act as bridges, enhancing the coupling across the interface and enabling better heat flow,” says Jun Liu, associate professor in the Department of Mechanical and Aerospace Engineering at North Carolina State University. “Indeed, imperfection can sometimes lead to better outcomes.”

The results lay the groundwork for engineering new polymeric materials with ultrahigh thermal conductivity. These advanced materials will enable devices – from high-performance microchips to next-generation soft robotics – to operate cooler and more efficiently through improved heat dissipation.

Chemistry

Revolutionizing Magnetic Field Technology: A Breakthrough Design for MRI and Magnetic Levitation

Two German physicists have reimagined how to create powerful and uniform magnetic fields using compact permanent magnets. By overcoming the limitations of the well-known Halbach array, which works only with infinitely long magnets, they engineered innovative 3D magnet arrangements that work in practical, finite-size setups. Their designs not only boost field strength but also enhance homogeneity, verified through real-world experiments. This game-changing advancement could help bring affordable MRI technology to underserved regions and power applications like particle accelerators and magnetic levitation systems.

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Physicists at the University of Bayreuth and Johannes Gutenberg University Mainz have made a groundbreaking discovery that could transform the way we generate magnetic fields. Prof. Dr. Ingo Rehberg and Dr. Peter Blümler developed an innovative approach to create homogeneous magnetic fields using compact, permanent magnets. This breakthrough design outperforms the traditional Halbach arrangement, which is ideal only for infinitely long and therefore unrealizable magnets.

The new approach presents optimal three-dimensional arrangements of very compact magnets, idealized by point dipoles. The researchers investigated the optimal orientation of the magnets for two geometries relevant to practical use: a single ring and a stacked double ring. This “focused” design allows the generation of homogeneous fields outside the magnet plane, enabling applications such as magnetic levitation systems.

To validate their theoretical predictions, Rehberg and Blümler constructed magnet arrays from 16 FeNdB cuboids mounted on 3D-printed supports. The resulting magnetic fields were measured and compared with theoretical calculations, revealing excellent agreement. In terms of both magnetic field strength and homogeneity, the new configurations clearly outperform the classical Halbach arrangement.

The potential applications of this breakthrough design are vast. Conventional MRI technology relies on powerful superconducting magnets, which are technically complex and extremely costly. The new approach offers a promising alternative for generating homogeneous magnetic fields using permanent magnets. Additionally, this innovation could lead to advancements in particle accelerators and magnetic levitation systems.

This study was published in the renowned interdisciplinary journal Physical Review Applied, showcasing significant advances at the intersection of physics with engineering, materials science, chemistry, biology, and medicine. The implications of this breakthrough design are far-reaching, and further research is expected to uncover new possibilities for its applications.

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Chemistry

Breakthrough at Rice University Keeps CO2 Electrolyzers Running 50x Longer with a Surprisingly Simple Method

A Rice University team discovered that bubbling CO₂ through a mild acid dramatically improves the lifespan and efficiency of electrochemical devices that convert CO₂ into useful fuels. This simple trick prevents salt buildup—a major barrier to commercialization—by altering local chemistry just enough to keep salts dissolved and flowing. The result? A device that ran for over 4,500 hours without clogging, using common catalysts and scalable technology. It’s a breakthrough that could make green CO₂ conversion far more viable in the real world.

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The researchers at Rice University have made a groundbreaking discovery that vastly improves the stability of electrochemical devices converting carbon dioxide into useful fuels and chemicals. Their innovative approach involves simply sending the CO2 through an acid bubbler, which dramatically extends the operational life of these devices by more than 50 times.

Electrochemical CO2 reduction (CO2RR) is a promising green technology that uses electricity to transform climate-warming CO2 into valuable products like carbon monoxide, ethylene, or alcohols. These products can be further refined into fuels or used in industrial processes, potentially turning a major pollutant into a feedstock.

However, the practical implementation of this technology has been hindered by poor system stability due to salt buildup in gas flow channels. This issue occurs when potassium ions migrate from the anolyte across the anion exchange membrane to the cathode reaction zone and combine with CO2 under high pH conditions.

To combat this problem, the Rice team tried a clever twist on standard procedures. Instead of using water to humidify the CO2 gas input into the reactor, they bubbled the gas through an acid solution such as hydrochloric, formic, or acetic acid.

The vapor from the acid altered local chemistry in trace amounts, preventing salt crystallization and channel blockage. The effect was remarkable: systems operated stably for over 4,500 hours in a scaled-up electrolyzer, compared to just about 80 hours under standard water-humidified CO2 conditions.

This breakthrough has significant implications for the development of carbon capture and utilization technologies. By extending the lifespan of CO2 electrolyzers, this innovation can help make these technologies more commercially viable and sustainable.

The simplicity of this approach is noteworthy, as it requires only small tweaks to existing humidification setups, which means it can be adopted without significant redesigns or added costs. This makes it an attractive solution for industries looking to integrate carbon utilization technologies into their operations.

This work was supported by the Robert A. Welch Foundation, Rice University, the National Science Foundation, and the David and Lucile Packard Foundation. The researchers’ findings have the potential to transform the field of CO2RR and pave the way for more durable, scalable electrochemical devices that can efficiently convert CO2 into valuable products.

The study’s authors highlight the significance of this discovery, saying it “addresses a long-standing obstacle with a low-cost, easily implementable solution.” They also emphasize its potential impact on making carbon utilization technologies more commercially viable and sustainable.

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Chemistry

“Rewriting Chemistry with Light: A Breakthrough in Fossil Fuel Transformation”

Researchers at Colorado State University have developed a new photoredox catalysis system that uses visible light mimicking photosynthesis to drive energy-intensive chemical reactions at room temperature. This groundbreaking process could significantly reduce the energy required in chemical manufacturing, especially in industries reliant on fossil fuels.

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The world is on the cusp of a revolutionary change in the way we transform fossil fuels into useful modern chemicals. Researchers at Colorado State University have made a groundbreaking discovery that uses light to rewrite the chemistry of fossil fuels, reducing energy demands and associated pollution. This breakthrough, published in Science, could be a game-changer for industries reliant on chemical manufacturing.

At the forefront of this research are professors Garret Miyake and Robert Paton from the Department of Chemistry and the Center for Sustainable Photoredox Catalysis (SuPRCat). Inspired by photosynthesis, their organic photoredox catalysis system harnesses visible light to gently alter the properties of chemical compounds. By exposing them to two separate photons, the team’s system generates energy needed for desired reactions, performing super-reducing reactions that are normally difficult and energy-intensive.

The research has shown remarkable results on aromatic hydrocarbons – resistant compounds like benzene in fossil fuels. Miyake boasts that their technology is “the most efficient system currently available” for reducing these compounds, paving the way for the production of chemicals needed for plastics and medicine.

This work continues the efforts of the U.S. National Science Foundation Center for Sustainable Photoredox Catalysis at CSU, led by Miyake as its director. This multi-institution research effort aims to transform chemical synthesis processes across various uses, making synthetic and computational chemists team up to understand the fundamental chemical nature of photoredox catalysis.

Katharine Covert, program director for the NSF Centers for Chemical Innovation program, highlights the importance of photoredox catalysis in pharmaceutical development and other industries. Through the NSF Center for Sustainable Photoredox Catalysis, researchers are developing catalysis systems similar to the one described in this paper to support energy-efficient production of ammonia for fertilizers, the breakdown of PFAS forever chemicals, and the upcycling of plastics.

Miyake emphasizes the urgency of meeting these challenges and making a more sustainable future for our world. He concludes that “the world has a timeclock that is expiring,” and we must develop sustainable technologies before it’s too late.

This breakthrough has far-reaching implications, not just in chemical manufacturing but also in addressing pressing environmental concerns. As researchers continue to push the boundaries of what’s possible with light-based chemistry, one thing is certain – the future of fossil fuel transformation has never looked brighter.

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