Special Features

Interesting facts about plastics and rubber

We come across plastics and rubber everywhere in our daily lives. Discover fascinating stories, surprising facts and interesting background information – from historical developments and well-known products to key figures and innovations in the industry.

Results (423)

  • Water vapor in the atmosphere may be prime renewable energy source

    A new Tel Aviv University study finds that water vapor in the atmosphere may serve as a potential renewable energy source in the future. The search for renewable energy sources, which include wind, solar, hydroelectric dams, geothermal, and biomass, has preoccupied scientists and policymakers alike, due to their enormous potential in the fight against climate change. A new Tel Aviv University study finds that water vapor in the atmosphere may serve as a potential renewable energy source in the future. The research, led by Prof. Colin Price in collaboration with Prof. Hadas Saaroni and doctoral student Judi Lax, all of TAU's Porter School of the Environment and Earth Sciences, is based on the discovery that electricity materializes in the interaction between water molecules and metal surfaces. It was published in Scientific Reports on May 6, 2020. "We sought to capitalize on a naturally occurring phenomenon: electricity from water," explains Prof. Price. "Electricity in thunderstorms is generated only by water in its different phases - water vapor, water droplets, and ice. Twenty minutes of cloud development is how we get from water droplets to huge electric discharges - lightning - some half a mile in length." The researchers set out to try to produce a tiny low-voltage battery that utilizes only humidity in the air, building on the findings of earlier discoveries. In the nineteenth century, for example, English physicist Michael Faraday discovered that water droplets could charge metal surfaces due to friction between the two. A much more recent study showed that certain metals spontaneously build up an electrical charge when exposed to humidity. The scientists conducted a laboratory experiment to determine the voltage between two different metals exposed to high relative humidity, while one is grounded. "We found that there was no voltage between them when the air was dry," Prof. Price explains. "But once the relative humidity rose above 60%, a voltage began to develop between the two isolated metal surfaces. When we lowered the humidity level to below 60%, the voltage disappeared. When we carried out the experiment outside in natural conditions, we saw the same results. "Water is a very special molecule. During molecular collisions, it can transfer an electrical charge from one molecule to the other. Through friction, it can build up a kind of static electricity," says Prof. Price. "We tried to reproduce electricity in the lab and found that different isolated metal surfaces will build up different amounts of charge from water vapor in the atmosphere, but only if the air relative humidity is above 60%. This occurs nearly every day in the summer in Israel and every day in most tropical countries." According to Prof. Price, this study challenges established ideas about humidity and its potential as an energy source. "People know that dry air results in static electricity and you sometimes get 'shocks' you when you touch a metal door handle. Water is normally thought of as a good conductor of electricity, not something that can build up charge on a surface. However, it seems that things are different once the relative humidity exceeds a certain threshold," he says. The researchers, however, showed that humid air may be a source of charging surfaces to voltages of around one volt. "If a AA battery is 1.5V, there may be a practical application in the future: to develop batteries that can be charged from water vapor in the air," Prof. Price adds. "The results may be particularly important as a renewable source of energy in developing countries, where many communities still do not have access to electricity, but the humidity is constantly about 60%," Prof. Price concludes. Reference Lax et al., On the Spontaneous Build-Up of Voltage between Dissimilar Metals Under High Relative Humidity Conditions, Scientific Reports 10 (2020), http://dx.doi.org/10.1038/s41598-020-64409-2

    Learn more

  • Renewable fuel from carbon dioxide with the aid of solar energy

    Researchers at Linköping University, Sweden, are attempting to convert carbon dioxide, a greenhouse gas, to fuel using energy from sunlight. Recent results have shown that it is possible to use their technique to selectively produce methane, carbon monoxide or formic acid from carbon dioxide and water. The study has been published in ACS Nano. Plants convert carbon dioxide and water to oxygen and high-energy sugars, which they use as "fuel" to grow. They obtain their energy from sunlight. Jianwu Sun and his colleagues at Linköping University are attempting to imitate this reaction, known as photosynthesis, used by plants to capture carbon dioxide from air and convert it to chemical fuels, such as methane, ethanol and methanol. The method is currently at a research stage, and the long-term objective of the scientists is to convert solar energy to fuel efficiently. "By converting carbon dioxide to fuel with the aid of solar energy, this technique could contribute to the development of sources of renewable energy and reduce the impact on the climate of the combustion of fossil fuels", says Jianwu Sun, senior lecturer in the Department of Physics, Chemistry and Biology at Linköping University. Graphene is one of the thinnest materials that exist, consisting of a single layer of carbon atoms. It is elastic, flexible, transparent to sunlight, and a good conductor of electricity. This combination of properties ensures that graphene has potential for use in applications such as electronics and biomedicine. But graphene alone is not suitable for the solar energy conversion application sought by the LiU researchers, and they have therefore combined the graphene with a semiconductor, cubic silicon carbide (3C-SiC). Scientists at Linköping University have previously developed a world-leading method to grow graphene on cubic silicon carbide, which consists of carbon and silicon. When the silicon carbide is heated, the silicon is vaporised, while the carbon atoms remain and re-construct in the form of a graphene layer. The researchers have previously shown that it is possible to place up to four layers of graphene on top of each other in a controlled manner. They have combined the graphene and cubic silicon carbide to develop a graphene-based photoelectrode that preserves the ability of cubic silicon carbide to capture the energy of sunlight and create charge carriers. The graphene functions as a conducting transparent layer while protecting the silicon carbide. The performance of the graphene-based technique is controlled by several factors, an important one of which is the quality of the interface between the graphene and the semiconductor. The scientists have looked at the properties of this interface in detail. They show in the article that they can tailor the layers of graphene on the silicon carbide and control the properties of the graphene-based photoelectrode. The conversion of carbon dioxide is in this way made more efficient, while the stabilities of the components are at the same time improved. The photoelectrode developed by the researchers can be combined with cathodes of various metals, such as copper, zinc or bismuth. Different chemical compounds, such as methane, carbon monoxide and formic acid, can be selectively formed from carbon dioxide and water by selecting suitable metal cathodes. "Most importantly, we have demonstrated that we can use solar energy to control the conversion of carbon dioxide to methane, carbon monoxide or formic acid", says Jianwu Sun. Methane is used as a fuel in vehicles adapted to use gaseous fuels. Carbon monoxide and formic acid can either be further processed such that they can function as fuels, or they can be used in industry." Reference Li et al., Atomic-Scale Tuning of Graphene/Cubic SiC Schottky Junction for Stable Low-Bias Photoelectrochemical Solar-to-Fuel Conversion, ACS Nano 14 (2020) 4905-4915, http://dx.doi.org/10.1021/acsnano.0c00986

    Learn more

  • Researchers develop 3D-printable material that mimics biological tissues

    Their motivation: dissipation controlled across length scales from the resin chemistry (mesoscale), to the microscale lattice architecture, and the overall macrostructure of printed structures. Image: N/A University of Colorado Denver researchers are the first to 3D print a complex, porous lattice structure using liquid crystal elastomers creating devices that can mimic cartilage and other biological tissues. Biological tissues have evolved over millennia to be perfectly optimized for their specific functions. Take cartilage as an example. It's a compliant, elastic tissue that's soft enough to cushion joints, but strong enough to resist compression and withstand the substantial load bearing of our bodies: key for running, jumping, and our daily wear and tear. Creating synthetic replacements which truly match the properties and behaviors of biological tissues hasn't been easy. But University of Colorado Denver scientists, led by mechanical engineer professor Chris Yakacki, PhD, are the first to 3D print a complex, porous lattice structure using liquid crystal elastomers (LCEs) creating devices that can finally mimic cartilage and other biological tissues. The CU Denver team, including professor Kai Yu, PhD, postdoctoral fellow Devesh Mistry, PhD, and doctoral student Nicholas Traugutt, as well as scientists from the Southern University of Science and Technology in China, reported its findings this week in the journal Advanced Materials. Revolution in the manufacturing of LCEs Yakacki, who works out of CU Denver's Smart Materials and Biomechanics (SMAB) Lab, began working with LCEs in 2012. The soft, multifunctional materials are known for their elasticity and extraordinary ability to dissipate high energy. In 2018, Yakacki received an NSF CAREER award to revolutionize the manufacturability of LCEs and several rounds of funding to develop them as a shock absorber for football helmets. Even then, he knew its applications could go further. "Everyone's heard of liquid crystals because you stare at them in your phone display," says Yakacki. "And you've likely heard of liquid crystal polymers because that's exactly what Kevlar is. Our challenge was to get them into soft polymers, like elastomers, to use them as shock absorbers. That's when you go down the layers of complexity." LCEs are tricky to manipulate. Until now, most researchers could create either large objects with minimal detail or high detail in practically microscopic structures. But as with phone screens, big devices with high resolutions are where the future lies. Yakacki and his team's chemicals and printing process took the difficulty down to nearly zero. Shining a light on honey-like resin For their study, Yakacki and his team explored a 3D printing process called digital light processing (DLP). The team developed a honey-like LC resin that, when hit with ultraviolet light, cures--forming new bonds in a succession of thin photopolymer layers. The final cured resin forms a soft, strong, and compliant elastomer. When printed in lattice structures--levels of patterning akin to a honeycomb--that's when it began to mimic cartilage. The group printed several structures, including a tiny, detailed lotus flower and a prototype of a spinal fusion cage, creating the largest LCE device with the most detail. The combination of the resin and printing process also led to 12 times greater rate-dependence and up to 27 times greater strain-energy dissipation compared to those printed from a commercially available photocurable elastomer resin. From football helmets to the spine Going forward, the structures have several applications, like shock-absorbing football helmet foam or even small biomedical implants for toes. Yakacki is most excited about its possibilities in the spine. LCE spinal cage prototype

    Learn more

  • Functional polymers to improve thermal stability of bioplastics

    One of the key objectives for contemporary chemistry is to improve thermomechanical properties of polymers, in particular, thermostability of bioplastics. In this paper, the team concentrated on researching oligomer and polymer materials with macrocyclic compounds characterized by enhanced thermostability. "Such products have lower vitrification temperatures, which makes them more malleable in comparison with commercial polylactic acid," says co-author, Research Associate Pavel Padnya. Polycondensation products of lactic acid (poly- and oligolactides) are of great interest for targeted drug delivery and implant design. A width of the range of their applications is due to a number of practically important properties, such as biocompatibility and biodegradability, non-toxicity and mechanical strength. "Modification of the obtained polymers with various additives can improve their properties and expand possible applications. One of the strategies to increase the stability of materials in biological media and to make drug loading possible is to obtain branched, or, as they are called, star-shaped polymers," explains Padnya. "We've been working on this topic for five years thanks to Russian Science Foundation's funding. We have had some non-trivial results for biodegradable polymers," adds team leader, Professor Ivan Stoikov. In the course of the study, new functional star-shaped polymers of lactic acid were obtained. Researchers chose macrocyclic compounds, thiacalixarenes, as the "crosslinking units" of polymer chains. An important result of this work is that the dependence of the structure of the obtained oligo- and polymer products on the synthesis temperature and the nature of the solvents used, as well as on the spatial structures selected for the "crosslinking" of chains of macrocyclic compounds, was established. This development can have a significant impact on the use of polymers in medicine: it turned out that the obtained compounds have an affinity for a certain type of xanthene dyes - a means for medical diagnostics and the study of biochemical processes in cells. Reference Gorbachuk et al., Towards novel functional polymers: Ring-opening polymerization of l-lactide with p-tert-butylthiacalix[4]arene derivatives, Reactive and Functional Polymers 150 (2020), https://doi.org/10.1016/j.reactfunctpolym.2020.104546

    Learn more

  • A new strategy for the optimal electroreduction of Co2 to high-value products

    Three strategies employed in this study to modulate local CO2 concentration in a catalyst layer (top) and the relationship between local CO2 concentration and the selectivity for multi-carbon products (bottom).Note that maximum selectivity is achieved at a moderate local CO2 concentration. I: KAIST Researchers suggest that modulation of local CO2 concentration improves the selectivity, conversion rate, and electrode stability, and shed a new light on the electrochemical CO2 reduction technology for controlling emissions at a low cost. A KAIST research team presented three novel approaches for modulating local carbon dioxide (CO2) concentration in gas-diffusion electrode (GDE)-based flow electrolyzers. Their study also empirically demonstrated that providing a moderate local CO2 concentration is effective in promoting Carbon-Carbon (C-C) coupling reactions toward the production of multi-carbon molecules. This work, featured in the May 20th issue of Joule, serves as a rational guide to tune CO2 mass transport for the optimal production of valuable multi-carbon products. Amid global efforts to reduce and recycle anthropogenic CO2 emissions, CO2 electrolysis holds great promise for converting CO2 into useful chemicals that were traditionally derived from fossil fuels. Many researches have been attempting to improve the selectivity of CO2 for commercially and industrially high-value multi-carbon products such as ethylene, ethanol, and 1-propanol, due to their high energy density and large market size. In order to achieve the highly-selective conversion of CO2 into valuable multi-carbon products, past studies have focused on the design of catalysts and the tuning of local environment related to pH, cations, and molecular additives. Conventional CO2 electrolytic systems relied heavily on an alkaline electrolyte that is often consumed in large quantities when reacting with CO2, and thus led to an increase in the operational costs. Moreover, the life span of a catalyst electrode was short, due to its inherent chemical reactivity. In their recent study, a group of KAIST researchers led by Professor Jihun Oh from the Department of Materials Science and Engineering reported that the local CO2 concentration has been an overlooked factor that largely affects the selectivity toward multi-carbon products. Professor Oh and his researchers Dr. Ying Chuan Tan, Hakhyeon Song, and Kelvin Berm Lee proposed that there is an intimate relation between local CO2 and multi-carbon product selectivity during electrochemical CO2 reduction reactions. The team employed the mass-transport modeling of a GDE-based flow electrolyzer that utilizes copper oxide (Cu2O) nanoparticles as model catalysts. They then identified and applied three approaches to modulate the local CO2 concentration within a GDE-based electrolytic system, including 1) controlling the catalyst layer structure, 2) CO2 feed concentration, and 3) feed flow rate. Contrary to common intuition, the study showed that providing a maximum CO2 transport leads to suboptimal multi-carbon product faradaic efficiency. Instead, by restricting and providing a moderate local CO2 concentration, C-C coupling can be significantly enhanced. The researchers demonstrated experimentally that the selectivity rate increased from 25.4% to 61.9%, and from 5.9% to 22.6% for the CO2 conversion rate. When a cheap milder near-neutral electrolyte was used, the stability of the CO2 electrolytic system improved to a great extent, allowing over 10 hours of steady selective production of multi-carbon products. Dr. Tan, the lead author of the paper, said, "Our research clearly revealed that the optimization of the local CO2 concentration is the key to maximizing the efficiency of converting CO2 into high-value multi-carbon products." Professor Oh added, "This finding is expected to deliver new insights to the research community that variables affecting local CO2 concentration are also influential factors in the electrochemical CO2 reduction reaction performance. My colleagues and I hope that our study becomes a cornerstone for related technologies and their industrial applications." Reference Tan et al., Modulating Local CO2Concentration as aGeneral Strategy for Enhancing CC Couplingin CO2Electroreduction, Joule, http://dx.doi.org/10.1016/j.joule.2020.03.013

    Learn more

  • Super water-repellent materials are now durable enough for the real world

    A schematic representation of how the surface looks, and how the structure repels water. Image: Aalto University Superhydrophobic surfaces repel water like nothing else. This makes them extremely useful for antimicrobial coatings - as bacteria, viruses and other pathogens cannot cling to their surfaces. However, superhydrophobic surfaces have one major flaw - they are extremely susceptible to cuts, scratches or dents. If a superhydrophobic surface gets damaged, the damaged area can trap liquids and the benefits of the coating are lost. Now, however, a collaboration between researchers in China and Finland has developed an armour-plated superhydrophobic surface which can take repeated battering from sharp and blunt objects, and still repel liquids with world-record effectiveness. The research - which is the cover feature of this week's issue of Nature - has designed superhydrophobic surfaces that can be made out of metal, glass, or ceramic. The superhydrophobic properties of the surface come from nano-sized structures spread all over it. The trick is to pattern the surface of the material with a honeycomb-like structure of tiny inverted pyramids. The fragile water-repellent chemical is then coated on the inside the honeycomb. This prevents any liquid from sticking to the surface, and the fragile chemical coating is protected from damage by the pyramid's walls. "The armour can be made from almost any material, it's the interconnection of the surface frame that makes it strong and rigid," says Professor Robin Ras, a physicist at Aalto University whose research group was part of the project. "We made the armour with honeycombs of different sizes, shapes and materials. The beauty of this result is that it is a generic concept that fits for many different materials, giving us the flexibility to design a wide range of durable waterproof surfaces." As well as their useful antimicrobial properties for biomedical technology, superhydrophobic surfaces can also be used more generally in any application requiring a liquid-repellent surface. One example is photovoltaics, where the build-up of moisture and dirt over time blocks the amount of light they can absorb, which reduces electricity production. Making a solar panel out of a superhydrophobic glass surface would maintain their efficiencies over long periods of time. Furthermore, as solar cells are often on roof tops and other difficult to reach locations, the repellent coatings would cut down the amount of cleaning that is needed. "By using the decoupled design, we introduce a new approach for designing a robust superhydrophobic surface. Our future work would be to push this method further, and to transfer robust superhydrophobic surfaces to different materials and its commercialization" said Professor Xu Deng, the leader of the group at the University of Electronic Science and Technology of China in Chengdu who took part in this research. Other desirable applications for superhydrophobic surfaces include in machines and on vehicles, where conditions can be very tough for brittle materials for long periods of time. To simulate these working environments, the researchers subjected their new surfaces to extreme conditions, including baking them at 100 °C nonstop for weeks, immersing them in highly corrosive liquids for hours, blasting them with high-pressure water jets, and subjecting them to physical exertion in extreme humidity. The surfaces were still able to repel liquid as effectively as before. Now that the strengths of this new material design have been demonstrated, future research will explore its broad potential in real-world applications. Reference Wang et al., Design of robust superhydrophobic surfaces, Nature 582 (2020) 55-59, http://dx.doi.org/10.1038/s41586-020-2331-8

    Learn more

  • Recycling plastics together, simple and fast

    Scientists successfully blended different types of plastics to be recycled together, providing a solution to the environmental problem of plastic waste and adding economic value to plastic materials. Image: Limin Bao, Shinshu University Recycling plastic faces several challenges, one of which is recycling different types of plastics together, because they have varying properties, each of which need to be addressed accordingly. Separating and treating each type of plastic adds to the cost of recycling plastic, which reduces the incentive to do so, despite the irreversible and detrimental biological cost of plastics in the environment. Researchers Tingan LIN and Limin BAO of Shinshu University and their colleague examined the recyclability and sustainable development of thermoplastic materials. Material characteristics were also examined. A simple and fast treatment using a blending process would allow plastics to be useful again, rather than sitting in landfill. Plastics are the most used manmade material after steel and cement and they do not decompose like natural materials. This has lead to a lot of unwanted plastic in the environment. Melt or burn are the only ways to eliminate plastic waste, but cause other problems such as toxic fumes and add to global warming. Therefore, a method to melt different plastics together is urgently needed. Polypropylene is a thermoplastics which means it is a plastic that can be heated and reshaped. It is used a lot in industry and household applications. The plastics examined in this study, thermoplastic polyurethane and polypropylene have significantly different melting points at 145 C° and 165 C°, so melting them together posed a challenge. To solve this issue, LIN et al. added an appropriate compatibilizer which acts as a go-between the plastics, which successfully enabled them to be processed together at the same time. The quality of the plastic was not undermined. The researchers were able to efficiently produce thermoplastic blends using the melt extrusion process and injection molded process. Only a small amount of the compatibilizer, polypropylene grafted maleic anhydride was needed to do so. This finding would allow for unwanted plastic to be economically valued again and protect wildlife and the environment from further pollution. Professor Bao hopes to continue the study of thermal behaviors to see how they affect the reusability of thermoplastic-based materials. For more information please read their paper: Polypropylene/thermoplastic polyurethane blends: mechanical characterizations, recyclability and sustainable development of thermoplastic materials. Reference Ting An Lin, Jia-Horng Lin and Limin Bao, Polypropylene/thermoplastic polyurethane blends: mechanical characterizations, recyclability and sustainable development of thermoplastic materials, Journal of Materials Research and Technology 9 (2020) 5304-5312, https://doi.org/10.1016/j.jmrt.2020.03.056

    Learn more

  • New method predicts spin dynamics of materials for quantum computing

    This illustration represents spin relaxation due to the coupling with lattice vibrations, as predicted from fully quantum-mechanical calculations. Image: Xinran Dongfang Researchers at UC Santa Cruz have developed a theoretical foundation and new computational tools for predicting a material's spin dynamics, a key property for building solid-state quantum computing platforms and other applications of spintronics. Spin is a fundamental property of electrons and other particles, and the rapidly growing field of spintronics uses spin states in a manner analogous to the use of electrical charge in electronics. Spin can be used as the basis for qubits (quantum bits) and single-photon emitters in applications of quantum information science, including quantum computation, communication, and sensing. Qubits can be made from any quantum system that has two states, but the challenge is to maintain quantum coherence (a relationship between quantum states) long enough to allow manipulation of the qubits. Decoherence means a loss of information from the system, and spin qubits can lose coherence by interacting with their environment through, for example, lattice vibrations within the material. "The key property for quantum information science is the lifetime of the spin states, known as the spin relaxation and decoherence time," said Yuan Ping, assistant professor of chemistry at UC Santa Cruz. "For quantum information applications, we need materials with long spin relaxation times." In a paper published June 3 in Nature Communications, Ping and her coauthors at UCSC and Rensselaer Polytechnic Institute present a new theoretical framework and computational tools for accurately predicting the spin relaxation time of any material, which was not previously possible. "These days, people just make a material and try it to see whether it works. Now we have the predictive capability from quantum mechanics that will allow us to design materials with the properties we want for applications in quantum information science," she said. "And if you have a promising material, this can tell you how to change it to make it better." The researchers established methods for determining spin dynamics from first principles, meaning that no empirical parameters from experimental measurements are needed to do the calculations. They also showed that their approach is generalizable to different types of materials with vastly different crystal symmetries and electronic structures. For example, they predicted accurately the spin relaxation time of centrosymmetric materials such as silicon, ferromagnetic iron, and graphene, as well as non-centrosymmetric materials such as molybdenum disulfide and gallium nitride, highlighting the predictive power of their method for a broad range of quantum materials. By enabling the rational design of materials, instead of searching blindly and testing a wide range of materials experimentally, these new methods could enable rapid advances in the field of quantum information technologies. Reference Xu et al.,Spin-phonon relaxation from a universal ab initio density-matrix approach, Nature Communications 11 (2020), s41467-020-16063-5), https://www.nature.com/articles/s41467-020-16063-5

    Learn more

  • The nature of glass-forming liquids is more clear

    Researchers from The University of Tokyo revealed a key structural feature of glass-forming liquids that may help solve a decades-long physics debate. Image: Institute of Industrial Science, The University of Tokyo Researchers from The University of Tokyo have found that attractive and repulsive interactions between particles are both essential to form structural order that controls the dynamics of glass-forming liquids. This knowledge will help understanding why a liquid becomes so viscous before glass formation. Glass is such a common, everyday material that you probably don't think about it much. It may surprise you to learn that researchers today still don't understand how glass forms. Figuring this out is important for glass industries and many other surprising applications of glasses. In a study published in Physical Review Letters, researchers from The University of Tokyo have revealed a structural origin of slow glassy dynamics that's aimed at understanding how a liquid becomes more viscous on cooling and can form a glass. The researchers found the correlation between the structure and motion of particles within simulated glass-forming liquids, on the level of individual particles and larger-scale particle assemblies. A central puzzle in glass physics is why a glass-forming liquid becomes so viscous before forming a glass. Whether this unusually slow motion in a liquid is mainly attributable to changes in spatial structure remains unknown. A physical model that reproduces how glass forms would help resolve this debate. "We used the concept of mutual information to understand the interrelationship between local particle arrangement and dynamics in glass-forming liquids," explains lead author of the study Hua Tong, who is now Assistant Professor in Shanghai Jiao Tong University. "Our results suggest that spatial structure controls the unique cooperative particle motion seen in glass-forming liquids." The researchers based their simulations on a structural order parameter that quantifies how closely the particles can pack together. The simulations focused on particle motions attributable to the original state of the particles, i.e., on the spatial structure. With the concept of mutual information, the simulations showed that particles structurally organize into assemblies that move more slowly than the rest of the particles, as seen in a real glass. "We found no clear relationship between particle-level potential energy and relaxation time," says Hajime Tanaka, senior author. "This suggests that slow glassy dynamics is fundamentally controlled by structural order formed by interparticle interactions, including both the repulsive and attractive parts." This liquid-to-glass research has many applications, including window glasses, optical fibers, and improved smart touch screens. Ultrahigh viscosity of a glass-forming material is very useful to deform it to arbitrary shape. By understanding what controls the viscosity of glass-forming liquids, the shape processability may be much improved. Reference Hua Tog and Hajime Tanaka, Role of attractive interactions in structure ordering and dynamics of glass-forming liquids, Physical Review Letters 124 (2020), DOI:10.1103/PhysRevLett.124.225501

    Learn more

  • Reducing Carbon Emissions in the Economy

    How can the economy be restructured to lower carbon emissions? What steps towards decarbonisation have nations already taken and how successful have they been? These are the questions to be addressed in a research project whose participants include scientists from the Institute for Political Science at Heidelberg University. Prof. Dr Jale Tosun will head up the work in Heidelberg which will start at the beginning of 2021. The work is part of a project based at the University of East Anglia (Great Britain), which the European Research Council (ERC) is funding with an ERC Advanced Grant for leading researchers. A total of nearly 2.4 million euros has been granted for the project. Approximately 530,000 euros is earmarked for the research in Heidelberg. In the “Deep Decarbonisation: The Democratic Challenge of Navigating Governance Traps” (DeepDCarb) project, coordinated by Prof. Dr Andrew Jordan of the University of East Anglia, the researchers first want to gain a fundamental understanding of climate policy action throughout the world. Datasets from the past 30 years that depict the activities of 41 countries with different levels of economic development will be used as a basis. The researchers will then look more closely at the processes that have already brought about the passage of climate policy laws and enactments in the past. “Further on, we will link political science research with approaches from the behavioural sciences. The central question is how should decision-making situations be set up to achieve long-term goals, like reducing global warming to 1.5 degrees,” explains Prof. Tosun. The researchers in Heidelberg will be creating empirical models to measure climate policy action and thus explain how climate policy is developed. “In past projects, we already developed approaches to measure legislative activities in this area for a large number of nations and over long periods of observation,” adds Prof. Tosun. “With our research activities in the DeepDCarb project, we plan to continue this work and facilitate insights that can be implemented in practice and thus benefit policy and public administration.”

    Learn more

  • 'A litmus paper for CO2:' Scientists develop paper-based sensors for carbon dioxide

    This paper-based sensor turns orange as it is exposed to carbon dioxide. Image courtesy of Al Meldrum. Image: Al Meldrum A new sensor for detecting carbon dioxide can be manufactured on a simple piece of paper, according to a new study by University of Alberta physicists. "You can basically think of it as a litmus paper for carbon dioxide," said Al Meldrum, professor in the Department of Physics and co-author on the study led by graduate student Hui Wang. "The work showed that you can make a sensitive carbon dioxide detector out of a simple piece of paper. One could easily imagine mass produced sensors for carbon dioxide or other gases using the same basic methods." The sensor, which changes colours based on the amount of carbon dioxide in the environment, has many potential applications--from industries that make use of carbon dioxide to smart buildings. And due to its paper base, the sensor is low cost to create and provides a simple template for mass production. "In smart buildings, carbon dioxide sensors can tell you about the occupancy and where people tend to congregate and spend their time, by detecting the carbon dioxide exhaled when we breathe," explained Meldrum. "This can help to aid in building usage and design. Carbon dioxide sensors currently can be very expensive if they are sensitive enough for many applications, so a cheap and mass-produced alternative could be beneficial for these applications." While this research demonstrates the sensing ability and performance of the technology, a mass-producible sensor would require further design, optimization, and packaging. Reference Wang et al.,An Ultrasensitive Fluorescent Paper-Based CO2 Sensor, ACS Applied Material Interface 12 (2020) 20507-20513, https://doi.org/10.1021/acsami.0c03405

    Learn more

  • From dark to light in a flash: Smart film lets windows switch autonomously

    Design concept of and fabrication procedures for the 3D scatterer. Image: KAIST Researchers have developed a new easy-to-use smart optical film technology that allows smart window devices to autonomously switch between transparent and opaque states in response to the surrounding light conditions. The proposed 3D hybrid nanocomposite film with a highly periodic network structure has empirically demonstrated its high speed and performance, enabling the smart window to quantify and self-regulate its high-contrast optical transmittance. As a proof of concept, a mobile-app-enabled smart window device for Internet of Things (IoT) applications has been realized using the proposed smart optical film with successful expansion to the 3-by-3-inch scale. This energy-efficient and cost-effective technology holds great promise for future use in various applications that require active optical transmission modulation. Flexible optical transmission modulation technologies for smart applications including privacy-protection windows, zero-energy buildings, and beam projection screens have been in the spotlight in recent years. Conventional technologies that used external stimuli such as electricity, heat, or light to modulate optical transmission had only limited applications due to their slow response speeds, unnecessary color switching, and low durability, stability, and safety. The optical transmission modulation contrast achieved by controlling the light scattering interfaces on non-periodic 2D surface structures that often have low optical density such as cracks, wrinkles, and pillars is also generally low. In addition, since the light scattering interfaces are exposed and not subject to any passivation, they can be vulnerable to external damage and may lose optical transmission modulation functions. Furthermore, in-plane scattering interfaces that randomly exist on the surface make large-area modulation with uniformity difficult. Mechanical and optical simulations of the 3D scatterer. Image: KAIST Inspired by these limitations, a KAIST research team led by Professor Seokwoo Jeon from the Department of Materials Science and Engineering and Professor Jung-Wuk Hong of the Civil and Environmental Engineering Department used proximity-field nanopatterning (PnP) technology that effectively produces highly periodic 3D hybrid nanostructures, and an atomic layer deposition (ALD) technique that allows the precise control of oxide deposition and the high-quality fabrication of semiconductor devices. The team then successfully produced a large-scale smart optical film with a size of 3 by 3 inches in which ultrathin alumina nanoshells are inserted between the elastomers in a periodic 3D nanonetwork. This "mechano-responsive" 3D hybrid nanocomposite film with a highly periodic network structure is the largest smart optical transmission modulation film that exists. The film has been shown to have state-of-the-art optical transmission modulation of up to 74% at visible wavelengths from 90% initial transmission to 16% in the scattering state under strain. Its durability and stability were proved by more than 10,000 tests of harsh mechanical deformation including stretching, releasing, bending, and being placed under high temperatures of up to 70°C. When this film was used, the transmittance of the smart window device was adjusted promptly and automatically within one second in response to the surrounding light conditions. Through these experiments, the underlying physics of optical scattering phenomena occurring in the heterogeneous interfaces were identified. Their findings were reported in the online edition of Advanced Science on April 26. KAIST Professor Jong-Hwa Shin's group and Professor Young-Seok Shim at Silla University also collaborated on this project. Demonstrations of the internet of things (IoT) applications: a self-regulating mechano-responsive smart window (MSW) device and a beam projection screen. Image: KAIST Donghwi Cho, a PhD candidate in materials science and engineering at KAIST and co-lead author of the study, said, "Our smart optical film technology can better control high-contrast optical transmittance by relatively simple operating principles and with low energy consumption and costs." "When this technology is applied by simply attaching the film to a conventional smart window glass surface without replacing the existing window system, fast switching and uniform tinting are possible while also securing durability, stability, and safety. In addition, its wide range of applications for stretchable or rollable devices such as wall-type displays for a beam projection screen will also fulfill aesthetic needs," he added. Reference Cho et al.,High‐Contrast Optical Modulation from Strain‐Induced Nanogaps at 3D Heterogeneous Interfaces, Advanced Science (2020), https://doi.org/10.1002/advs.201903708

    Learn more