The new superlight, conductive materials could make better flexible electronics.

The ordered structure of a graphene aerogel (left) mimics that of a strong, flexible aquatic plant stem (right) with parallel layers that are connected by short bridges.

Credit: ACS Nano

Ultralight and exceptionally strong, graphene aerogels are attractive materials for use as catalysts, electrodes, and flexible electronics. But so far it has been hard to make them both strong and elastic. Researchers have now overcome that hurdle by making a squishable graphene aerogel that mimics an aquatic plant’s highly ordered porous structure (ACS Nano 2017, DOI: 10.1021/acsnano.7b01815).

The new, conductive aerogel springs back to its original shape after being squeezed to half its size with more than 6,000 times its weight. The aerogel retains 85% of its original strength even after being squeezed more than 1,000 times. In comparison, aerogels with random pore structures that the researchers made and tested lost more than half of their strength after just 10 compression cycles. The combination of low density, strength, super elasticity, and conductivity are critical for applications in which the material undergoes large volume changes, such as an absorbent that soaks up chemicals or an electrode that takes up and releases ions.

Scientists have typically made graphene aerogels by chemically reducing graphene oxide flakes suspended in water and freeze-drying them. More recently, scientists used 3-D printing with graphene inks to make porous, compressible graphene aerogels.

To assess the material’s potential for use in sensors and electronics, the team tested its conductivity and how it varies with compression. When they connected the aerogel to a light-emitting diode in a circuit, they found that squeezing the aerogel increased conductivity as they expected, demonstrated by the LED glowing brighter. “The conductivity of the aerogel is high considering its low density,” Bai says. “With higher density, the aerogel should be more conductive.”

This is a clever, low-cost, and scalable freezing process to generate a new aerogel microstructure, says Peter Pauzauskie of the University of Washington. “This kind of detailed graphene microstructure would be very expensive and difficult to achieve” using other methods, including 3-D printing, he says

Plastics recycling technology roundup

A Canadian company’s bottle-to-bottle recycling operation gets a boost, and a recyclable oxygen-barrier film is developed for food packaging.

Marker potential:Marker technologies won’t be a silver bullet to boosting recycling rates, but fluorescent pigments and digital watermarks could help protect the quality of recovered plastics, according to an article at canadianpackaging.com. The report is based on an interview with Richard McKinlay, head of engineering and research at the U.K. firm Axion Consulting.

Bottle-to-bottle boost: Recycling International reports that Canadian water bottler Ice River Springs has boosted its recycling performance through the installation of a Starlinger PET recycling line. The recoSTAR PET bottle-to-bottle line came with a Nordson BKG Flex Disc filter cartridge that has improved melt flow filtering performance by boosting output and reducing melt loss.

First-place finish: Canada-based Pyrowave, a company that uses microwave radiation in the depolymerization of PS, announced that it wonfirst prize at the 6th IQ-CHem International Chemistry Innovation Competition, held in Moscow. The technology recovers styrene monomers from the plastics. Contest judges included representatives from The Dow Chemical Co., Linde, LG, Honeywell UOP, DuPont, 3M, BASF and Sinopec.

Recyclable packaging: Keurig Green Mountain announced that it will accelerate its timeline for ensuring all of its K-Cups are recyclable in Canada, Plastics News reports. The Vermont-based company will, by the end of 2018, produce all of its cups in Canada with a recyclable PP, replacing multi-material pods.

PS push: Trade association PlasticsEurope launched an effort to promote innovative recycling solutions for polystyrene, with a focus on chemical recycling. The group will work to engage the value chain to develop and industrialize promising new technologies, including those that can recycle post-consumer materials into food-contact packaging.

Recyclable barrier film: U.S. PE supplier Nova Chemicals has developed an easily recyclable oxygen-barrier film, according to Recycling International. The new packaging, which could replaced mixed-material packaging, is compatible with the HDPE stream.

New material may help cut battery costs for electric cars, cellphones

Researchers at the University of Texas at Dallas and Seoul National University have designed a novel battery cathode material that offers a potentially lower-cost, more eco-friendly option to lithium-ion batteries. Their sodium-ion design, which retains the high energy density of a lithium-ion cathode, replaces the most of the lithium atoms (green) with sodium (yellow). The layered structure of the new material also incorporates manganese (purple) and oxygen (red). The research is published in the journal Advanced Materials. Credit: University of Texas at Dallas

In the battle of the batteries, lithium-ion technology is the reigning champion, powering that cellphone in your pocket as well as an increasing number of electric vehicles on the road.
   "Lithium is a more expensive, limited resource that must be mined from just a few areas on the globe," Cho said. "There are no mining issues with sodium—it can be extracted from seawater. Unfortunately, although sodium-ion batteries might be less expensive than those using lithium, sodium tends to provide 20 percent lower energy density than lithium."

The energy density, or energy storage capacity, of a battery determines the run time of a device.

"We used our previous experience and thought about these issues—how can we combine these ideas to come up with something new to solve the problem?" Cho said.

A battery consists of a positive electrode, or anode; a negative electrode, or cathode; and an electrolyte in between. In a standard lithium-ion battery, the cathode is made of lithium, cobalt, nickel and oxygen, while the anode is made of graphite, a type of carbon. When the battery charges, lithium ions move through the electrolyte to the anode and attach to the carbon. During discharge, the lithium ions move back to the cathode and provide electric energy to run devices.

"There was great hope several years ago in using manganese oxide in lithium-ion battery cathodes to increase capacity, but unfortunately, that combination becomes unstable," Cho said.

In the design developed by Cho and his colleagues, sodium replaces most of the lithium in the cathode, and manganese is used instead of the more expensive and rarer elements cobalt and nickel.

"Our sodium-ion material is more stable, but it still maintains the high energy capacity of lithium," Cho said. "And we believe this is scalable, which is the whole point of our research. We want to make the material in such a way that the process is compatible with commercial mass production."

for more info visit https://m.phys.org/news/2017-07-material-battery-electric-cars-cellphones.html

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A ceramic sample compacted at room temperature in an ETH Zurich lab.

ETH material scientists have developed a new method of manufacturing ceramics that does not require the starting materials to be fired. Instead, they are compacted under high pressure at room temperature in a significantly more energy-efficient process.      The manufacture of cement, bricks, bathroom tiles and porcelain crockery normally requires a great deal of heat: a kiln is used to fire the ceramic materials at temperatures well in excess of 1,000°C. Now, material scientists from ETH Zurich have developed what seems at first glance to be an astonishingly simple method of manufacture that works at room temperature. The scientists used a calcium carbonate nanopowder as the starting material and instead of firing it, they added a small amount of water and then compacted it.

       “The manufacturing process is based on the geological process of rock formation,” explains Florian Bouville, a postdoc in the group of André Studart, Professor of Complex Materials. Sedimentary rock is formed from sediment that is compressed over millions of years through the pressure exerted by overlying deposits. This process turns calcium carbonate sediment into limestone with the help of the surrounding water. As the ETH researchers used calcium carbonate with an extremely fine particle size (nanoparticles) as the starting material, their compacting process took only an hour. “Our work is the first evidence that a piece of ceramic material can be manufactured at room temperature in such a short amount of time and with relatively low pressures,” says ETH professor Studart.         According to the scientists, in the long term, the new approach of cold sintering even has the potential to lead to more environmentally friendly substitutes for cement-based materials. However, great research efforts are needed to reach this goal. Cement production is not only energy-intensive, but it also generates large amounts of CO2 – unlike potential cold-sintered replacement materials.

© ETH Zurich News

Scientists produce dialysis membrane made from graphene

Material can filter nanometer-sized molecules at 10 to 100 times the rate of commercial membranes.

1) Graphene, grown on copper foil, is pressed against a supporting sheet of polycarbonate. 2) The polycarbonate acts to peel the graphene from the copper. 3) Using interfacial polymerization, researchers seal large tears and defects in graphene. 4) Next, they use oxygen plasma to etch pores of specific sizes in graphene.

         Dialysis, in the most general sense, is the process by which molecules filter out of one solution, by diffusing through a membrane, into a more dilute solution. Outside of hemodialysis, which removes waste from blood, scientists use dialysis to purify drugs, remove residue from chemical solutions, and isolate molecules for medical diagnosis, typically by allowing the materials to pass through a porous membrane.

          Today’s commercial dialysis membranes separate molecules slowly, in part due to their makeup: They are relatively thick, and the pores that tunnel through such dense membranes do so in winding paths, making it difficult for target molecules to quickly pass through.

             Now MIT engineers have fabricated a functional dialysis membrane from a sheet of graphene — a single layer of carbon atoms, linked end to end in hexagonal configuration like that of chicken wire. The graphene membrane, about the size of a fingernail, is less than 1 nanometer thick. (The thinnest existing memranes are about 20 nanometers thick.) The team’s membrane is able to filter out nanometer-sized molecules from aqueous solutions up to 10 times faster than state-of-the-art membranes, with the graphene itself being up to 100 times faster.

          While graphene has largely been explored for applications in electronics, Piran Kidambi, a postdoc in MIT’s Department of Mechanical Engineering, says the team’s findings demonstrate that graphene may improve membrane technology, particularly for lab-scale separation processes and potentially for hemodialysis.

         “Because graphene is so thin, diffusion across it will be extremely fast,” Kidambi says. “A molecule doesn’t have to do this tedious job of going through all these tortuous pores in a thick membrane before exiting the other side. Moving graphene into this regime of biological separation is very exciting.”

Upcycling 'fast fashion' to reduce waste and pollution

Creative use of fast fashion to save nature.

Pollution created by making and dyeing clothes has pitted the fashion industry and environmentalists against each other. Now, the advent of “fast fashion”-trendy clothing affordable enough to be disposable- has strained that relationship even more. But what if we could recycle clothes like we recycle paper, or even upcycle them? Scientists report today new progress toward that goal.
        People don’t want to spend much money on textiles anymore, but poor-quality garments don’t last,” Simone Haslinger explained. “A small amount might be recycled as cleaning rags, but the rest ends up in landfills, where it degrades and releases carbon dioxide, a major greenhouse gas. Also, there isn’t much arable land anymore for cotton fields, as we also have to produce food for a growing population.”
   All these reasons amount to a big incentive to recycle clothing, and some efforts are already underway, such as take-back programmes. But even industry representatives admit in news reports that only a small percentage gets recycled.
     A better strategy, said Herbert Sixta, PhD, who heads the biorefineries research group at Aalto University, is to upcycle worn-out garments: “We want to not only recycle garments, but we want to really produce the best possible textiles so that recycled fibre is even better than native fibre.” But achieving this goal isn’t simple. Cotton and other fibre are often blended with polyester in fabrics such as “cotton-polyester blends,” which complicates processing.

Previous research showed that many ionic liquids can dissolve cellulose. But the resulting material couldn’t then be re-used to make new fibre. Then about five years ago, Sixta’s team found an ionic liquid-1,5-diazabicyclo[4.3.0]non-5-ene acetate - that could dissolve cellulose from wood pulp, producing a material that could be spun into fibre. Later testing showed that these fibres are stronger than commercially available viscose and feel similar to lyocell. Lyocell is also known by the brand name Tencel, which is a fibre favoured by eco-conscious designers because it’s made of wood pulp.

See the Story in Chemical Today magazine

http://www.worldofchemicals.com/digitalissue/chemical-today-june-2017/20

A 30-year-old man in Delhi was left with a hole in his stomach and had to get that part removed after he drank down a cocktail laced with liquid nitrogen.

The man was partying at a Gurgaon pub with friends. They ordered the pub's latest offering - a cocktail with liquid nitrogen. He drank it before the smoke coming out of the drink could evaporate. What followed was extremely restlessness, abdomen swelling and breathing difficulty. The man was rushed to a nearby hospital, where blood tests revealed severe lactic acidosis – high level of lactic acid in the blood which commonly results from oxygen deprivation in the body.

        What he had consumed was liquid nitrogen that has a boiling point of -195.8 degree Celsius and is used to instantly freeze food and drinks. The colourless liquid is also used to cool computers and in cryogenic medical procedures like removing warts and cancerous tissues by freezing them. When used to freeze drinks, these should only be consumed after the nitrogen has completely evaporated.

         “Consuming liquid nitrogen can cause havoc in a person’s system. By nature, liquid nitrogen expands manifolds and evaporates when left at room temperature. The gas did not have an escape route after the person consumed it and the sphincter closed, this is what led to a perforation (a hole) in his stomach,” said Dr Amit Deepta Goswami, the person’s doctor and consultant of bariatric and minimally invasive surgery at Columbia Asia Hospital, Gurgaon.