Category Archives: coatings

More of the ‘blackest black’

There’s a very good November 11, 2019 article by Natalie Angier for the New York Times on carbon nanotubes (CNTs) and the colour black,

On a laboratory bench at the National Institute of Standards and Technology was a square tray with two black disks inside, each about the width of the top of a Dixie cup. Both disks were undeniably black, yet they didn’t look quite the same.

Solomon Woods, 49, a trim, dark-haired, soft-spoken physicist, was about to demonstrate how different they were, and how serenely voracious a black could be.

“The human eye is extraordinarily sensitive to light,” Dr. Woods said. Throw a few dozen photons its way, a few dozen quantum-sized packets of light, and the eye can readily track them.

Dr. Woods pulled a laser pointer from his pocket. “This pointer,” he said, “puts out 100 trillion photons per second.” He switched on the laser and began slowly sweeping its bright beam across the surface of the tray.

On hitting the white background, the light bounced back almost unimpeded, as rude as a glaring headlight in a rearview mirror.

The beam moved to the first black disk, a rondel of engineered carbon now more than a decade old. The light dimmed significantly, as a sizable tranche of the incident photons were absorbed by the black pigment, yet the glow remained surprisingly strong.

Finally Dr. Woods trained his pointer on the second black disk, and suddenly the laser’s brilliant beam, its brash photonic probe, simply — disappeared. Trillions of light particles were striking the black disk, and virtually none were winking back up again. It was like watching a circus performer swallow a sword, or a husband “share” your plate of French fries: Hey, where did it all go?

N.I.S.T. disk number two was an example of advanced ultra-black technology: elaborately engineered arrays of tiny carbon cylinders, or nanotubes, designed to capture and muzzle any light they encounter. Blacker is the new black, and researchers here and abroad are working to create ever more efficient light traps, which means fabricating materials that look ever darker, ever flatter, ever more ripped from the void.

The N.I.S.T. ultra-black absorbs at least 99.99 percent of the light that stumbles into its nanotube forest. But scientists at the Massachusetts Institute of Technology reported in September the creation of a carbon nanotube coating that they claim captures better than 99.995 of the incident light.

… The more fastidious and reliable the ultra-black, the more broadly useful it will prove to be — in solar power generators, radiometers, industrial baffles and telescopes primed to detect the faintest light fluxes as a distant planet traverses the face of its star.

Psychology and metaphors

It’s not all technical, Angier goes on to mention the psychological and metaphorical aspects,

Psychologists have gathered evidence that black is among the most metaphorically loaded of all colors, and that we absorb our often contradictory impressions about black at a young age.

Reporting earlier this year in the Quarterly Journal of Experimental Psychology, Robin Kramer and Joanne Prior of the University of Lincoln in the United Kingdom compared color associations in a group of 104 children, aged 5 to 10, with those of 100 university students.

The researchers showed subjects drawings in which a lineup of six otherwise identical images differed only in some aspect of color. The T-shirt of a boy taking a test, for example, was switched from black to blue to green to red to white to yellow. The same for a businessman’s necktie, a schoolgirl’s dress, a dog’s collar, a boxer’s gloves.

Participants were asked to link images with traits. Which boy was likeliest to cheat on the test? Which man was likely to be in charge at work? Which girl was the smartest in her class, which dog the scariest?

Again and again, among both children and young adults, black pulled ahead of nearly every color but red. Black was the color of cheating, and black was the color of cleverness. A black tie was the mark of a boss, a black collar the sign of a pit bull. Black was the color of strength and of winning. Black was the color of rage.

Art

Then, there is the world of art,

For artists, black is basal and nonnegotiable, the source of shadow, line, volume, perspective and mood. “There is a black which is old and a black which is fresh,” Ad Reinhardt, the abstract expressionist artist, said. “Lustrous black and dull black, black in sunlight and black in shadow.”

So essential is black to any aesthetic act that, as David Scott Kastan and Stephen Farthing describe in their scholarly yet highly entertaining book, “On Color,” modern artists have long squabbled over who pioneered the ultimate visual distillation: the all-black painting.

Was it the Russian Constructivist Aleksandr Rodchenko, who in 1918 created a series of eight seemingly all-black canvases? No, insisted the American artist Barnett Newman: Those works were very dark brown, not black. He, Mr. Newman, deserved credit for his 1949 opus, “Abraham,” which in 1966 he described as “the first and still the only black painting in history.”

But what about Kazimir Malevich’s “Black Square” of 1915? True, it was a black square against a white background, but the black part was the point. Then again, the English polymath Robert Fludd had engraved a black square in a white border back in 1617.

Clearly, said Alfred H. Barr, Jr., the first director of the Museum of Modern Art, “Each generation must paint its own black square.”

Structural colour

Solomon and his NIST colleagues and the MIT scientists are all trying to create materials with structural colour, in this case, black. Angier goes on to discuss structural colour in nature mentioning bird feathers and spiders as examples of where you might find superblacks. For anyone unfamiliar with structural colour, the colour is not achieved with pigment or dye but with tiny structures, usually measured at the nanoscale, on a bird’s wing, a spider’s belly, a plant leaf, etc. Structural colour does not fade or change . Still, it’s possible to destroy the structures, i.e., the colour, but light and time will not have any effect since it’s the tiny structures and their optical properties which are producing the colour . (Even after all these years, my favourite structural colour story remains a Feb. 1, 2013 article, Color from Structure, by Cristina Luiggi for The Scientist magazine. For a shorter version, I excerpted parts of Luiggi’s story for my February 7, 2013 posting.)

The examples of structural colour in Angier’s article were new to me. However, there are many, many examples elsewhere,. You can find some here by using the terms ‘structural colour’ or ‘structural color’ in the blog’s search engine.

Angier’s is a really good article and I strongly recommend reading it if you have time but I’m a little surprised she doesn’t mention Vantablack and the artistic feud. More about that in a moment,

Massachusetts Institute of Technology and a ‘blacker black’

According to MIT (Massachusetts Institute of Technology), they have the blackest black. It too is courtesy of carbon nanotubes.

The Redemption of Vanity, is a work of art by MIT artist in residence Diemut Strebe that has been realized together with Brian L. Wardle, Professor of Aeronautics and Astronautics and Director of necstlab and Nano- Engineered Composite aerospace STructures (NECST) Consortium and his team Drs. Luiz Acauan and Estelle Cohen. Strebe’s residency at MIT is supported by the Center for Art, Science & Technology (CAST). Image: Diemut Strebe

What you see in the above ‘The Redemption of Vanity’ was on show at the New York Stock Exchange (NYSE) from September 13 – November 29, 2019. It’s both an art piece and a demonstration of MIT’s blackest black.

There are two new releases from MIT. The first is the more technical one. From a Sept. 12, 2019 MIT news release,

With apologies to “Spinal Tap,” it appears that black can, indeed, get more black.

MIT engineers report today that they have cooked up a material that is 10 times blacker than anything that has previously been reported. The material is made from vertically aligned carbon nanotubes, or CNTs — microscopic filaments of carbon, like a fuzzy forest of tiny trees, that the team grew on a surface of chlorine-etched aluminum foil. The foil captures at least 99.995 percent* of any incoming light, making it the blackest material on record.

The researchers have published their findings today in the journal ACS-Applied Materials and Interfaces. They are also showcasing the cloak-like material as part of a new exhibit today at the New York Stock Exchange, titled “The Redemption of Vanity.”

The artwork, conceived by Diemut Strebe, an artist-in-residence at the MIT Center for Art, Science, and Technology, in collaboration with Brian Wardle, professor of aeronautics and astronautics at MIT, and his group, and MIT Center for Art, Science, and Technology artist-in-residence Diemut Strebe, features a 16.78-carat natural yellow diamond from LJ West Diamonds, estimated to be worth $2 million, which the team coated with the new, ultrablack CNT material. The effect is arresting: The gem, normally brilliantly faceted, appears as a flat, black void.

Wardle says the CNT material, aside from making an artistic statement, may also be of practical use, for instance in optical blinders that reduce unwanted glare, to help space telescopes spot orbiting exoplanets.

“There are optical and space science applications for very black materials, and of course, artists have been interested in black, going back well before the Renaissance,” Wardle says. “Our material is 10 times blacker than anything that’s ever been reported, but I think the blackest black is a constantly moving target. Someone will find a blacker material, and eventually we’ll understand all the underlying mechanisms, and will be able to properly engineer the ultimate black.”

Wardle’s co-author on the paper is former MIT postdoc Kehang Cui, now a professor at Shanghai Jiao Tong University.

Into the void

Wardle and Cui didn’t intend to engineer an ultrablack material. Instead, they were experimenting with ways to grow carbon nanotubes on electrically conducting materials such as aluminum, to boost their electrical and thermal properties.

But in attempting to grow CNTs on aluminum, Cui ran up against a barrier, literally: an ever-present layer of oxide that coats aluminum when it is exposed to air. This oxide layer acts as an insulator, blocking rather than conducting electricity and heat. As he cast about for ways to remove aluminum’s oxide layer, Cui found a solution in salt, or sodium chloride.

At the time, Wardle’s group was using salt and other pantry products, such as baking soda and detergent, to grow carbon nanotubes. In their tests with salt, Cui noticed that chloride ions were eating away at aluminum’s surface and dissolving its oxide layer.

“This etching process is common for many metals,” Cui says. “For instance, ships suffer from corrosion of chlorine-based ocean water. Now we’re using this process to our advantage.”

Cui found that if he soaked aluminum foil in saltwater, he could remove the oxide layer. He then transferred the foil to an oxygen-free environment to prevent reoxidation, and finally, placed the etched aluminum in an oven, where the group carried out techniques to grow carbon nanotubes via a process called chemical vapor deposition.

By removing the oxide layer, the researchers were able to grow carbon nanotubes on aluminum, at much lower temperatures than they otherwise would, by about 100 degrees Celsius. They also saw that the combination of CNTs on aluminum significantly enhanced the material’s thermal and electrical properties — a finding that they expected.

What surprised them was the material’s color.

“I remember noticing how black it was before growing carbon nanotubes on it, and then after growth, it looked even darker,” Cui recalls. “So I thought I should measure the optical reflectance of the sample.

“Our group does not usually focus on optical properties of materials, but this work was going on at the same time as our art-science collaborations with Diemut, so art influenced science in this case,” says Wardle.

Wardle and Cui, who have applied for a patent on the technology, are making the new CNT process freely available to any artist to use for a noncommercial art project.

“Built to take abuse”

Cui measured the amount of light reflected by the material, not just from directly overhead, but also from every other possible angle. The results showed that the material absorbed at least 99.995 percent of incoming light, from every angle. In other words, it reflected 10 times less light than all other superblack materials, including Vantablack. If the material contained bumps or ridges, or features of any kind, no matter what angle it was viewed from, these features would be invisible, obscured in a void of black.  

The researchers aren’t entirely sure of the mechanism contributing to the material’s opacity, but they suspect that it may have something to do with the combination of etched aluminum, which is somewhat blackened, with the carbon nanotubes. Scientists believe that forests of carbon nanotubes can trap and convert most incoming light to heat, reflecting very little of it back out as light, thereby giving CNTs a particularly black shade.

“CNT forests of different varieties are known to be extremely black, but there is a lack of mechanistic understanding as to why this material is the blackest. That needs further study,” Wardle says.

The material is already gaining interest in the aerospace community. Astrophysicist and Nobel laureate John Mather, who was not involved in the research, is exploring the possibility of using Wardle’s material as the basis for a star shade — a massive black shade that would shield a space telescope from stray light.

“Optical instruments like cameras and telescopes have to get rid of unwanted glare, so you can see what you want to see,” Mather says. “Would you like to see an Earth orbiting another star? We need something very black. … And this black has to be tough to withstand a rocket launch. Old versions were fragile forests of fur, but these are more like pot scrubbers — built to take abuse.”

[Note] An earlier version of this story stated that the new material captures more than 99.96 percent of incoming light. That number has been updated to be more precise; the material absorbs at least 99.995 of incoming light.

Here’s an August 29, 2019 news release from MIT announcing the then upcoming show. Usually I’d expect to see a research paper associated with this work but this time it seems to an art exhibit only,

The MIT Center for Art, Science &Technology (CAST) and the New York Stock Exchange (NYSE) will present The Redemption of Vanity,created by artist Diemut Strebe in collaboration with MIT scientist Brian Wardle and his lab, on view at the New York Stock Exchange September 13, 2019 -November 25, 2019. For the work, a 16.78 carat natural yellow diamond valued at $2 million from L.J.West was coated using a new procedure of generating carbon nanotubes (CNTs), recently measured to be the blackest black ever created, which makes the diamond seem to disappear into an invisible void. The patented carbon nanotube technology (CNT) absorbs more than 99.96% of light and was developed by Professor Wardle and his necstlablab at MIT.

“Any object covered with this CNT material loses all its plasticity and appears entirely flat, abbreviated/reduced to a black silhouette. In outright contradiction to this we see that a diamond,while made of the very same element (carbon) performs the most intense reflection of light on earth.Because of the extremely high light absorbtive qualities of the CNTs, any object, in this case a large diamond coated with CNT’s, becomes a kind of black hole absent of shadows,“ explains Strebe.“The unification of extreme opposites in one object and the particular aesthetic features of the CNTs caught my imagination for this art project.”

“Strebe’s art-science collaboration caused us to look at the optical properties of our new CNT growth, and we discovered that these particular CNTs are blacker than all other reported materials by an order of magnitude across the visible spectrum”, says Wardle. The MIT team is offering the process for any artist to use. “We do not believe in exclusive ownership of any material or idea for any artwork and have opened our method to any artist,” say Strebe and Wardle.“

The project explores material and immaterial value attached to objects and concepts in reference to luxury, society and to art. We are presenting the literal devaluation of a diamond, which is highly symbolic and of high economic value.It presents a challenge to art market mechanisms on the one hand, while expressing at the same time questions of the value of art in a broader way. In this sense it manifests an inquiry into the significance of the value of objects of art and the art market,” says Strebe. “We are honored to present this work at The New York Stock Exchange, which I believe to be a most fitting location to consider the ideas embedded in The Redemption of Vanity.”

“The New York Stock Exchange, a center of financial and technological innovation for 227 years, is the perfect venue to display Diemut Strebe and Professor Brian Wardle’s collaboration. Their work brings together cutting-edge nanotube technology and a natural diamond, which is a symbol of both value and longevity,” said John Tuttle, NYSE Group Vice Chairman & Chief Commercial Officer.

“We welcome all scientists and artists to venture into the world of natural color diamonds. The Redemption of Vanity exemplifies the bond between art, science, and luxury. The 16-carat vivid yellow diamond in the exhibit spent millions of years in complete darkness, deep below the earth’s surface. It was only recently unearthed —a once-in-a-lifetime discovery of exquisite size and color. Now the diamond will relive its journey to darkness as it is covered in the blackest of materials. Once again, it will become a reminder that something rare and beautiful can exist even in darkness,”said Larry West.

The “disappearing” diamond in The Redemption of Vanity is a $2 Million Fancy Vivid Yellow SI1 (GIA), Radiant shape, from color diamond specialist, L.J. West Diamonds Inc. of New York.

The Redemption of Vanity, conceived by Diemut Strebe, has been realized with Brian L. Wardle, Professor of Aeronautics and Astronautics and Director of necstlab and Nano-Engineered Composite aerospace STructures (NECST) Consortium and his team Drs. Luiz Acauan and Estelle Cohen, in conjunction with Strebe’s residency at MIT supported by the Center for Art, Science & Technology (CAST).

ABOUT THE ARTISTS

Diemut Strebe is a conceptual artist based in Boston, MA and a MIT CAST Visiting Artist. She has collaborated with several MIT faculty, including Noam Chomsky and Robert Langer on Sugababe (2014), Litmus (2014) and Yeast Expression(2015); Seth Lloyd and Dirk Englund on Wigner’s Friends(2014); Alan Guth on Plötzlich! (2018); researchers in William Tisdale’s Lab on The Origin of the Works of Art(2018); Regina Barzilay and Elchanan Mossel on The Prayer (2019); and Ken Kamrin and John Brisson on The Gymnast (2019). Strebe is represented by the Ronald Feldman Gallery.

Brian L. Wardle is a Professor of Aeronautics and Astronautics at MIT and the director of the necstlab research group and MIT’s Nano-Engineered Composite aerospace STructures (NECST) Consortium. Wardle previously worked with CAST Visiting Artist Trevor Paglen on The Last Picturesproject (2012).

ABOUT THE MIT CENTER FOR ART, SCIENCE & TECHNOLOGY

A major cross-school initiative, the MIT Center for Art, Science & Technology (CAST) creates new opportunities for art, science and technology to thrive as interrelated, mutually informing modes of exploration, knowledge and discovery. CAST’s multidisciplinary platform presents performing and visual arts programs, supports research projects for artists working with science and engineering labs, and sponsors symposia, classes, workshops, design studios, lectures and publications. The Center is funded in part by a generous grant from the Andrew W. Mellon Foundation. Evan Ziporyn is the Faculty Director and Leila W. Kinney is the Executive Director.Since its inception in 2012, CAST has been the catalyst for more than 150 artist residencies and collaborative projects with MIT faculty and students, including numerous cross-disciplinary courses, workshops, concert series, multimedia projects, lectures and symposia. The visiting artists program is a cornerstone of CAST’s activities, which encourages cross-fertilization among disciplines and intensive interaction with MIT’s faculty and students. More info at https://arts.mit.edu/cast/ .

HISTORY OF VISITING ARTISTS AT MIT

Since the late 1960s, MIT has been a leader in integrating the arts and pioneering a model for collaboration among artists, scientists and engineers in a research setting. CAST’s Visiting Artists Program brings internationally acclaimed artists to engage with MIT’s creative community in ways that are mutually enlightening for the artists and for faculty, students and research staff at the Institute. Artists who have worked extensively at MIT include Mel Chin, Olafur Eliasson, Rick Lowe, Vik Muniz, Trevor Paglen, Tomás Saraceno, Maya Beiser, Agnieszka Kurant, and Anicka Yi.

ABOUT L.J. WEST DIAMONDS

L.J. West Diamonds is a three generation natural color diamond whole sale rfounded in the late 1970’s by Larry J. West and based in New York City. L.J. West has established itself as one of the world’s prominent houses for some of the most rare and important exotic natural fancy color diamonds to have ever been unearthed. This collection includes a vast color spectrum of rare pink, blue, yellow, green, orange and red diamonds. L.J. West is an expert in every phase of the jewelry process –from sourcing to the cutting, polishing and final design. Each exceptional jewel is carefully set to become a unique work of art.The Redemption of Vanity is on view at the New York Stock Exchange by appointment only.

Press viewing: September 13, 2019 at 3pmNew York Stock Exchange, 11 Wall Street, New York, NY 10005RSVP required. Please check-in at the blue tent at 2 Broad Street(at the corner of Wall and Broad Streets). All guests are required to show a government issued photo ID and go through airport-like security upon entering the NYSE.NYSE follows a business casual dress code -jeans & sneakers are not permitted.

No word yet if there will be other showings.

An artistic feud (of sorts)

Earlier this year, I updated a story on Vantablack. It was the blackest black, blocking 99.8% of light when I featured it in a March 14, 2016 posting. The UK company making the announcement, Surrey NanoSystems, then laid the groundwork for an artistic feud when it granted exclusive rights to their carbon nanotube-based coating, Vantablack, to Sir Anish Kapoor mentioned here in an April 16, 2016 posting.

This exclusivity outraged some artists notably, Stuart Semple. In his first act of defiance, he created the pinkest pink. Next, came a Kickstarter campaign to fund Semple’s blackest black, which would be available to all artists except Anish Kapoor. You can read all about the pinkest pink and blackest black as per Semple in my February 21, 2019 posting. You can also get a bit of an update in an Oct. 17, 2019 Stuart Semple proffile by Berenice Baker for Verdict,

… so I managed to hire a scientist, Jemima, to work in the studio with me. She got really close to a super black, and we made our own pigment to this recipe and it was awesome, but we couldn’t afford to put it into manufacture because it cost £25,000.”

Semple launched a Kickstarter campaign and was amazed to raise half a million pounds, making it the second most-supported art Kickstarter of all time.

The ‘race to the blackest’ is well underway, with MIT researchers recently announcing a carbon nanotube-based black whose light absorption they tested by coasting a diamond. But Semple is determined that his black should be affordable by all artists and work like a paint, not only perform in laboratory conditions. He’s currently working with Jemima and two chemists to upgrade the recipe for Black 3.2.

I don’t know how Semple arrived at his blackest black. I think it’s unlikely that he achieved the result by working with carbon nanotubes since my understanding is that CNTs aren’t that easy to produce.

Finally

Interesting, eh? In just a few years scientists have progressed from achieving a 99.8% black to 99.999%. It doesn’t seem like that big a difference to me but with Solomon Woods, at the beginning of this post, making the point that our eyes are very sensitive to light, an artistic feud, and a study uncovering deep emotions, getting the blackest black is a much more artistically fraught endeavour than I had imagined.

Superhydrophobic nanoflowers

I’m getting to the science but first this video of what looks like jiggling jello,

In actuality, it’s a superhydrophobic coating demonstration and a July 2, 2019 news item on phys.org provides more information,

Plant leaves have a natural superpower—they’re designed with water repelling characteristics. Called a superhydrophobic surface, this trait allows leaves to cleanse themselves from dust particles. Inspired by such natural designs, a team of researchers at Texas A&M University has developed an innovative way to control the hydrophobicity of a surface to benefit to the biomedical field.

Researchers in Dr. Akhilesh K. Gaharwar’s lab in the Department of Biomedical Engineering have developed a “lotus effect” by incorporating atomic defects in nanomaterials, which could have widespread applications in the biomedical field including biosensing, lab-on-a-chip, blood-repellent, anti-fouling and self-cleaning applications.

A July 2, 2019 Texas A&M University news release (also on EurekAlert) by Jennifer Reiley, which originated the news item, expands on the theme,

Superhydrophobic materials are used extensively for self-cleaning characteristic of devices. However, current materials require alteration to the chemistry or topography of the surface to work. This limits the use of superhydrophobic materials.

“Designing hydrophobic surfaces and controlling the wetting behavior has long been of great interest, as it plays crucial role in accomplishing self-cleaning ability,” Gaharwar said. “However, there are limited biocompatible approach to control the wetting behavior of the surface as desired in several biomedical and biotechnological applications.”

The Texas A&M design adopts a ‘nanoflower-like’ assembly of two-dimensional (2D) atomic layers to protect the surface from wetting. The team recently released a study published in Chemical Communications. 2D nanomaterials are an ultrathin class of nanomaterials and have received considerable attention in research. Gaharwar’s lab used 2D molybdenum disulfide (MoS2), a new class of 2D nanomaterials that has shown enormous potential in nanoelectronics, optical sensors, renewable energy sources, catalysis and lubrication, but has not been investigated for biomedical applications. This innovative approach demonstrates applications of this unique class of materials to the biomedical industry.

“These 2D nanomaterials with their hexagonal packed layer repel water adherence, however, a missing atom from the top layer can allow easy access to water molecules by the next layer of atoms underneath making it transit from hydrophobic to hydrophilic,” said lead author of the study, Dr. Manish Jaiswal, a senior research associate in Gaharwar’s lab.

This innovative technique opens many doors for expanded applications in several scientific and technological areas. The superhydrophobic coating can be easily applied over various substrates such as glass, tissue paper, rubber or silica using the solvent evaporation method. These superhydrophobic coatings have wide-spread applications, not only in developing self-cleaning surfaces in nanoelectronics devices, but also for biomedical applications.

Specifically, the study demonstrated that blood and cell culture media containing proteins do not adhere to the surface, which is very promising. In addition, the team is currently exploring the potential applications of controlled hydrophobicity in stem cell fate.

Here’s a link to and a citation for the paper,

Superhydrophobic states of 2D nanomaterials controlled by atomic defects can modulate cell adhesion by Manish K. Jaiswal, Kanwar Abhay Singh, Giriraj Lokhande and Akhilesh K. Gaharwar. Chem. Commun., 2019, Advance Article DOI: 10.1039/C9CC00547A First published on 07 Jun 2019

This paper is open access.

A fire-retardant coating made of renewable nanocellulose materials

Firefighters everywhere are likely to appreciate the efforts of researchers at Texas A&M University (US) to a develop a non-toxic fire retardant coating. From a February 12, 2019 news item on Nanowerk (Note: A link has been removed),

Texas A&M University researchers are developing a new kind of flame-retardant coating using renewable, nontoxic materials readily found in nature, which could provide even more effective fire protection for several widely used materials.

Dr. Jaime Grunlan, the Linda & Ralph Schmidt ’68 Professor in the J. Mike Walker ’66 Department of Mechanical Engineering at Texas A&M, led the recently published research that is featured on the cover of a recent issue of the journal Advanced Materials Interfaces (“Super Gas Barrier and Fire Resistance of Nanoplatelet/Nanofibril Multilayer Thin Films”).

Successful development and implementation of the coating could provide better fire protection to materials including upholstered furniture, textiles and insulation.

“These coatings offer the opportunity to reduce the flammability of the polyurethane foam used in a variety of furniture throughout most people’s homes,” Grunlan noted.

A February 8, 2019 Texas A&M University news release (also on EurekAlert) by Steve Kuhlmann, which originated the news item, describes the work being done in collaboration with a Swedish team in more detail,

The project is a result of an ongoing collaboration between Grunlan and a group of researchers at KTH Royal Institute of Technology in Stockholm, Sweden, led by Lars Wagberg. The group, which specializes in utilizing nanocellulose, provided Grunlan with the ingredients he needed to complement his water-based coating procedure.

In nature, both the cellulose – a component of wood and various sea creatures – and clay – a component in soil and rock formations – act as mechanical reinforcements for the structures in which they are found.

“The uniqueness in this current study lies in the use of two naturally occurring nanomaterials, clay nanoplatelets and cellulose nanofibrils,” Grunlan said. “To the best of our knowledge, these ingredients have never been used to make a heat shielding or flame-retardant coating as a multilayer thin film deposited from water.”

Among the benefits gained from using this method include the coating’s ability to create an excellent oxygen barrier to plastic films – commonly used for food packaging – and better fire protection at a lower cost than other, more toxic ingredients traditionally used flame-retardant treatments.

To test the coatings, Grunlan and his colleagues applied the flexible polyurethane foam – often used in furniture cushions – and exposed it to fire using a butane torch to determine the level of protection the compounds provided.

While uncoated polyurethane foam immediately melts when exposed to flame, the foam treated with the researchers’ coating prevented the fire from damaging any further than surface level, leaving the foam underneath undamaged.

“The nanobrick wall structure of the coating reduces the temperature experienced by the underlying foam, which delays combustion,” Grunlan said. “This coating also serves to promote insulating char formation and reduces the release of fumes that feed a fire.”

With the research completed, Grunlan said the next step for the overall flame-retardant project is to transition the methods into industry for implementation and further development. 

Here’s a link to and a citation for the paper,

Super Gas Barrier and Fire Resistance of Nanoplatelet/Nanofibril Multilayer Thin Films by Shuang Qin, Maryam Ghanad Pour, Simone Lazar, Oruç Köklükaya, Joseph Gerringer, Yixuan Song, Lars Wågberg, Jaime C. Grunlan. Advanced Materials Interfaces Volume 6, Issue 2 January 23, 2019 1801424 DOI: https://doi.org/10.1002/admi.201801424 First published online: 16 November 2018

This paper is behind a paywall.

First textile to automatically trap or release heat, depending on conditions

A revolutionary fabric created at UMD reacts to environmental conditions to either trap heat or release it. (Photo by Faye Levine) Courtesy: University of Maryland

This may look like just another gauzy fabric but it has some special properties according to a February 7, 2019 news item on ScienceDaily,

Despite decades of innovation in fabrics with high-tech thermal properties that keep marathon runners cool or alpine hikers warm, there has never been a material that changes its insulating properties in response to the environment. Until now.

University of Maryland researchers have created a fabric that can automatically regulate the amount of heat that passes through it. When conditions are warm and moist, such as those near a sweating body, the fabric allows infrared radiation (heat) to pass through. When conditions become cooler and drier, the fabric reduces the heat that escapes. The development was reported in the February 8, 2019 issue of the journal Science.

A February 8, 2019 University of Maryland news release (also on EurekAlert [published Feb.7, 2019]) by Kimbra Cutlip delves further into the research,

The researchers created the fabric from specially engineered yarn coated with a conductive metal. Under hot, humid conditions, the strands of yarn compact and activate the coating, while cool, dry conditions reverse the action. The researchers refer to this as “gating”—essentially a tunable blind that transmits or blocks heat.

“This is the first technology that allows us to dynamically gate infrared radiation,” said YuHuang Wang, a professor of chemistry and biochemistry and one of the paper’s corresponding authors who directed the studies.

The base yarn for this new textile is created with fibers made of two different synthetic materials—one absorbs water and the other repels it. The strands are coated with carbon nanotubes, a special class of lightweight, carbon-based, conductive metal.

Because materials in the fibers both resist and absorb water, the fibers warp when exposed to humidity such as that surrounding a sweating body. That distortion brings the strands of yarn closer together, opening the pores in the fabric and creating a minor cooling effect by allowing heat to escape. More importantly, it modifies the electromagnetic coupling between the carbon nanotubes in the coating.

“You can think of this coupling effect like the bending of a radio antenna to change the wavelength or frequency it resonates with,” Wang said. “Imagine bringing two antennae close together to regulate the kind of electromagnetic wave they pick up. When the fabric fibers are brought closer together, the radiation they interact with changes. In clothing, that means the fabric interacts with the heat radiating from the human body.

”Depending on the tuning, the fabric either blocks infrared radiation or allows it to pass through. The reaction is almost instant, so before people realize it, the dynamic gating mechanism is either cooling them down or working in reverse to trap heat.
 
“The human body is a perfect radiator. It gives off heat quickly,” said Min Ouyang, a professor of physics at UMD and the paper’s other corresponding author. “For all of history, the only way to regulate the radiator has been to take clothes off or put clothes on. But this fabric is a true bidirectional regulator.

More work is needed before the fabric can be commercialized, but according to the researchers, materials used for the base fiber are readily available and the carbon coating can be easily added during the standard dyeing process.

Here’s a link to and a citation for the paper,

Dynamic gating of infrared radiation in a textile by Xu A. Zhang, Shangjie Yu, Beibei Xu, Min Li, Zhiwei Peng, Yongxin Wang, Shunliu Deng, Xiaojian Wu, Zupeng Wu, Min Ouyang, YuHuang Wang. Science 08 Feb 2019: Vol. 363, Issue 6427, pp. 619-623 DOI: 10.1126/science.aau1217

This paper is behind a paywall.

The van Gogh-Roosegaarde path, a solar powered bike path

From YouTube, Heijmans NV Published on Nov 12, 2014 Inspired by Vincent van Gogh’s work, the cycle path combines innovation and design with cultural heritage and tourism. The Van Gogh-Roosegaarde cycle path is being constructed by Heijmans from a design by Daan Roosegaarde and forms part of the Van Gogh cycle route in Brabant.

According to other sources, the path was inspired by van Gogh’s ‘Starry Night’. From a November 21, 2014 article by Elizabeth Montalbano for Design News (Note: A link has been removed),

The Dutch are known for their love of bicycling, and they’ve also long been early adopters of green-energy and smart-city technologies. So it seems fitting that a town in which painter Vincent van Gogh once lived has given him a very Dutch-like tribute — a bike path lit by a special smart paint in the style of the artist’s “Starry Night” painting.

Designed by artist Daan Roosegaarde of Studio Roosegaarde, the van Gogh-Roosegaarde bike path — in the Dutch town of Nuenen en Eindhoven, where van Gogh lived from 1883-1885 — is a kilometer long and features technologies developed as part of the Smart Highway project, a joint venture of the studio and Dutch infrastructure company Heijmans.

A team of 12 designers and engineers worked on the project for eight months, while site production took 10 days. The opening of the path marked the official launch of the international van Gogh 2015 year.

The path uses stones painted with a smart coating that charges by the heat of the sun during the day and then glow at night for up to eight hours. When there is not enough sunlight during the day to charge the stones, the path can draw electricity from a solar panel installed nearby. There are also LEDs in the path that provides lighting.

How does the technology work?

Despite my best efforts, I never did unearth a good technical explanation. There is some sort of photoluminescent powder or paint. I vote for a powder that’s been emulsified in a paint/coating. material. Somehow, this material is charged by sunlight and then at night glows with the help of a solar panel and light-emitting diodes (LEDs).

Here’s the clearest explanation I found; it’s from Dan Howarth’s November 12, 2014 article for dezeen.com (Note: A link has been removed), ,

The surface of the Van Gogh-Roosegaarde Bicycle Path is coated with a special paint that uses energy gathered during the day to glow after dark.


[Daan] Roosegaarde told Dezeen that this method of illumination is “more gentle to the eye and surrounding nature” that other lighting infrastructure, and creates a “connection with cultural history”.

A nearby solar panel is used to generate power to illuminate the coated surface, which was developed with infrastructure firm Heijmans. LEDs along the side of certain curves in the path cast extra light, meaning the path will still be partially lit if the weather has been too cloudy for the panel to charge the surface to its full brightness.

“It’s a new total system that is self-sufficient and practical, and just incredibly poetic,” said Roosegaarde.

Lily Hay Newman’s November 14, 2014 article for Slate.com succinctly sums up the technical aspects,

The path is coated in photoluminescent paint that’s also embedded with small LEDs powered by nearby solar panels. The path essentially charges all day so that it can glow during the night, and it also has backup power in case it’s overcast.

This October 30, 2012 article by Liat Clark for Wired.com provides a bit more detail about the powder/paint as Clark delves into the Roosegaarde Studo’s Smart Highway project (the cycle path made use of the same technology) ,

The studio has developed a photo-luminising powder that will replace road markings – it charges up in sunlight, giving it up to 10 hours of glow-in-the-dark time come nightfall. “It’s like the glow in the dark paint you and I had when we were children,” designer Roosegaarde explained, “but we teamed up with a paint manufacturer and pushed the development. Now, it’s almost radioactive“. [perhaps not the wisest choice of hyperbole]

Special paint will also be used to paint markers like snowflakes across the road’s surface – when temperatures fall to a certain point, these images will become visible, indicating that the surface will likely be slippery. Roosegaarde says this technology has been around for years, on things like baby food – the studio has just upscaled it.

Not everyone is in love

Shaunacy Ferro’s July 26, 2017 article for dentalfloss.com highlights a glow-in-the-dark path project for Singapore and a little criticism (Note: Links have been removed),

Glow-in-the-dark materials are no longer for toys. Photoluminescence can help cities feel safer at night, whether it’s part of a mural, a bike lane, or a highway. Glow-in-the-dark paths have been tested in several European cities (the above is a Van Gogh-inspired bike path by the Dutch artist Daan Roosegaarde) and in Texas, but now, the technology may be coming to Singapore. The city-state is currently developing a 15-mile greenway called the Rail Corridor, and it now has a glow-in-the-dark path, as Mashable reports.

The 328-foot stretch of glowing path is part of a test of multiple surface materials that might eventually be used throughout the park, depending on public opinion. In addition to the strontium aluminate-beaded [emphasis mine] path that glows at night, there are also three other 328-foot stretches of the path that are paved with fine gravel, cement aggregate, and part-grass/part-gravel. The glow-in-the-dark material embedded in the walkway absorbs UV light from the sun during the day and can emit light for up to eight hours once the sun goes down.

However, in practice, glow-in-the-dark paths can be less dazzling than they seem. [emphasis mine] Mashable’s reporter called the glowing effect on Singapore’s path “disappointingly feeble.” [emphasis mine] In 2014, a glowing highway-markings pilot by Studio Roosegaarde in the Netherlands revealed that the first road markings faded after exposure to heavy rains. [emphases mine] When it comes to glowing roads, the renderings tend to look better than the actual result, [emphasis mine] and there are still kinks to work out. (The studio worked the issue out eventually.) While a person walking or biking down Singapore’s glowing path might be able to tell that they were staying on the path better than if they were fumbling along dark pavement, it’s not the equivalent of a streetlight, for sure.

Ferro had reported earlier on Studio Roosegaarde’s Smart Highway project in an October 23, 2014 article for Fast Company where Ferro first mentioned the rain problem (Note: Links have been removed),

Glowing Lanes is a collaboration between Dutch engineering company Heijmans and Daan Roosegaarde, a tech-loving artist and designer whose previous work includes Intimacy 2.0, a dress that becomes transparent when the wearer gets aroused. The glow-in-the-dark lane markers are intended to increase road visibility in a more energy-efficient way than traditional street lighting. Photoluminescent paint charges during the day and slowly emits light over the course of eight hours during the evening.

After a few technical challenges (an early version of the markers didn’t fare so well in the rain), the final system has been installed, and according to Studio Roosegaarde, the kinks have been worked out, and initial reports of the paint fading were “overstated.” [emphases mine]

“This was part of any normal learning process,” according to an email from the studio’s PR, and “now the project is ‘matured.’”

But not to the point where it’s no longer a novelty. According to the email from Studio Roosegaarde, the glowing highway caused a minor traffic jam last night as people rushed to look at it.

… Roosegaarde has also been asked to create a smart highway design for Afsluitdijk–an almost 20-mile-long dike that connects North Holland to the province of Friesland across the water–and according to his studio, there are plans in the works to launch the glowing lanes in China and Japan as well.

Comments

In the following excerpt, there’s a reference to strontium aluminate-coated materials, given the interview which follows this section, the project in Singapore did not use the photoluminescent paint developed by Roosegaarde Studio. I found this paint reference in a July 26, 2017 article by Yi Shu Ng for Mashable (h/t Ferro’s July 26, 2017 article) which notes the product’s ubiquity,

The track glows because it’s got strontium aluminate compounds embedded in it — the chemical is commonly found in glow-in-the-dark products, which absorb ultraviolet light in the day, to emit luminescence at night.

There are some inconsistencies in the reporting about the number of hours, eight hours or 10 hours, the bicycle path or smart highway remains lit after being charged. Given that this was a newish technology being used in a new application, the rain problem and other technical glitches were to be expected. I wish the writer had been a little less dismissive and that the studio had been a little more forthcoming about how they solved the problems. In any case, I dug further and this is what I got.

Interview

I’m not sure who answered the questions but this comes direct from Studio Roosegaarde,

  • Could you give me a capsule description of what’s happened since the path was opened in 2014/15? For example, How does the bike path look these days? Does it still glow? Don’t the bicycles on the path destroy the ‘Starry Night’ pattern over time? Do the stones have to be coated over and over again to maintain their solar charging capacities? 

    The Van Gogh Path is still working perfectly and is visited every night by couples, tourists and local people. The stones are inside the concrete so are still in place and will work for a minimum of 10 years. It is great to see we have created a place of wonder. It is the most published bicycle path in the world. We have even had children books published about it.
  • Are there more bike paths like the Van Gogh Path in other parts of Holland and/or elsewhere?

    No, this is the only one. There have been some copycats in other countries.The Smart Highway project is still growing, and our recent Gates of Light is the next step of poetic and energy-neutral landscapes like the Van Gogh Path:  https://www.studioroosegaarde.net/project/gates-of-light
  • How has your project evolved? And, have there been any unanticipated benefits and/or setbacks? Is there a change in the technology, I noticed you were investigating bioluminscence.

    Yes, we are still developing new landscapes of the future. What we have learned from Van Gogh Path we have applied in new projects such as Glowing Nature: https://www.studioroosegaarde.net/project/glowing-nature We also do something new.
  • I was struck by how gentle the lighting is. I understand there has been some criticism about how much light the path radiates and I’m wondering about your thoughts on that.

    Yes, since the path is a nature protected environment, normal LED lighting was not allowed. So the light is gentle but still visible, and sustainable.There are some bad copy-cats using cheap materials which don’t work well, like the one in Singapore. But we are happy that our path is still working.

Thank you to the folks at Studio Roosegaarde for taking the time to provide this interview. Here are links to Studio Roosegaarde and their industrial partner, Heijmans.

Graphene-gilded artifacts (or artefacts)

Caption: L: An artist rendering of graphene gilding on Tutankhamun’s middle coffin (original photograph copyright: Griffith Institute, University of Oxford). R: Microscope image of a graphene crystal is shown on the palladium leaf. Although graphene is only a single atom thick, it can be observed in the scanning electron microscope. Here, a small crystal of graphene is shown to observe its edges. The team produces leaves where the graphene fully cover the metal surface. Credit: Original photograph copyright: Griffith Institute, University of Oxford

As icons go, Tutankhamun’s middle coffin ranks highly and it’s a great image to use as an example of what might be accomplished with graphene gilding. From a Sept. 10, 2018 news item on Nanowerk,

Gilding is the process of coating intricate artifacts with precious metals. Ancient Egyptians and Chinese coated their sculptures with thin metal films using gilding—and these golden sculptures have resisted corrosion, wear, and environmental degradation for thousands of years. The middle and outer coffins of Tutankhamun, for instance, are gold leaf gilded, as are many other ancient treasures.

In a new study, Illinois’ Sameh Tawfick, from the Department of Mechanical Science & Engineering (MechSE) and the Beckman Institute, inspired by this ancient process, has added a single layer of carbon atoms, known as graphene, on top of metal leaves—doubling the protective quality of gilding against wear and tear.

A Sept. 10, 2018 University of Illinois news release (also on EurekAlert), which originated the news item, offers more details,

Metal leaves, or foils, offer many advantages as a scalable coating material, including their commercial availability in large rolls and their comparatively low price. By bonding a single layer of graphene to the leaves, Tawfick and his team demonstrated unexpected benefits, including enhanced mechanical resistance. Their work presents exciting opportunities for protective coating applications on large structures like buildings or ship hulls, metal surfaces of consumer electronics, and small precious artifacts or jewelry.

“Adding one more layer of graphene atoms onto the palladium made it twice as resistant to indents than the bare leaves alone,” said Tawfick. “It’s also very attractive from a cost perspective. The amount of graphene needed to cover the gilded structures of the Carbide & Carbon Building in Chicago, for example, would be the size of the head of a pin.”

Additionally, the team developed a new technology to grow high-quality graphene directly on the surface of 150 nanometer-thin palladium leaves—in just 30 seconds. Using a process called chemical vapor deposition, in which the metal leaf is processed in a 1,100°C furnace, the bare palladium leaf acts as a catalyst, allowing the gases to react quickly.

“Chemical vapor deposition of graphene requires a very high temperature, which could melt the leaves or cause them to bead up by a process called solid state dewetting,” said Kaihao Zhang, PhD candidate in MechSE and lead author of the study. “The process we developed deposits the graphene quickly enough to avoid high-temperature degradation, it’s scalable, and it produces graphene of very high quality.”

Here’s a link to and a citation for the paper,

Gilding with Graphene: Rapid Chemical Vapor Deposition Synthesis of Graphene on Thin Metal Leaves by Kaihao Zhang, Charalampos Androulidakis, Mingze Chen, Sameh Tawfick. Advanced Functional Materials DOI: https://doi.org/10.1002/adfm.201804068 First published: 06 September 2018

This paper is behind  a paywall.

Colo(u)ring your carbon nanotubes

Finnish research is highlighted in an August 28, 2018 news item on phys.org,

A method developed at Aalto University, Finland, can produce large quantities of pristine single-walled carbon nanotubes in select shades of the rainbow. The secret is a fine-tuned fabrication process—and a small dose of carbon dioxide. The films could find applications in touch screen technologies or as coating agents for new types of solar cells.

An August 28, 2018 Aalto University press release (also on EurekAlert), which originated the news item, provides more detail,

Samples of the colourful carbon nanotube thin films, as produced in the fabrication reactor. Image: Aalto University.
 

Single-walled carbon nanotubes, or sheets of one atom-thick layers of graphene rolled up into different sizes and shapes, have found many uses in electronics and new touch screen devices. By nature, carbon nanotubes are typically black or a dark grey.

In their new study published in the Journal of the American Chemical Society (JACS), Aalto University researchers present a way to control the fabrication of carbon nanotube thin films so that they display a variety of different colours—for instance, green, brown, or a silvery grey.

The researchers believe this is the first time that coloured carbon nanotubes have been produced by direct synthesis. Using their invention, the colour is induced straight away in the fabrication process, not by employing a range of purifying techniques on finished, synthesized tubes.

With direct synthesis, large quantities of clean sample materials can be produced while also avoiding damage to the product in the purifying process—which makes it the most attractive approach for applications.

‘In theory, these coloured thin films could be used to make touch screens with many different colours, or solar cells that display completely new types of optical properties,’ says Esko Kauppinen, Professor at Aalto University.

To get carbon structures to display colours is a feat in itself. The underlying techniques needed to enable the colouration also imply finely detailed control of the structure of the nanotube structures. Kauppinen and his team’s unique method, which uses aerosols of metal and carbon, allows them to carefully manipulate and control the nanotube structure directly from the fabrication process.

‘Growing carbon nanotubes is, in a way, like planting trees: we need seeds, feeds, and solar heat. For us, aerosol nanoparticles of iron work as a catalyst or seed, carbon monoxide as the source for carbon, so feed, and a reactor gives heat at a temperature more than 850 degrees Celsius,’ says Dr. Hua Jiang, Senior Scientist at Aalto University.

Professor Kauppinen’s group has a long history of using these very resources in their singular production method. To add to their repertoire, they have recently experimented with administering small doses of carbon dioxide into the fabrication process.

‘Carbon dioxide acts as a kind of graft material that we can use to tune the growth of carbon nanotubes of various colors,’ explains Jiang.

With an advanced electron diffraction technique, the researchers were able to find out the precise atomic scale structure of their thin films. They found that they have very narrow chirality distributions, meaning that the orientation of the honeycomb-lattice of the tubes’ walls is almost uniform throughout the sample. The chirality more or less dictates the electrical properties carbon nanotubes can have, as well as their colour.

The method developed at Aalto University promises a simple and highly scalable way to fabricate carbon nanotube thin films in high yields.

‘Usually you have to choose between mass production or having good control over the structure of carbon nanotubes. With our breakthrough, we can do both,’ trusts Dr. Qiang Zhang, a postdoctoral researcher in the group.

Follow-up work is already underway.

‘We want to understand the science of how the addition of carbon dioxide tunes the structure of the nanotubes and creates colours. Our aim is to achieve full control of the growing process so that single-walled carbon nanotubes could be used as building blocks for the next generation of nanoelectronics devices,’ says professor Kauppinen.

Here’s a link to and a citation for the paper,

Direct Synthesis of Colorful Single-Walled Carbon Nanotube Thin Films by Yongping Liao, Hua Jiang, Nan Wei, Patrik Laiho, Qiang Zhang, Sabbir A. Khan, and Esko I. Kauppinen. J. Am. Chem. Soc., 2018, 140 (31), pp 9797–9800 DOI: 10.1021/jacs.8b05151 Publication Date (Web): July 26, 2018

Copyright © 2018 American Chemical Society

This paper appears to be open access.

For the curious, here’s a peek at the coloured carbon nanotube films,

 

Caption: Samples of the colorful carbon nanotube thin films, as produced in the fabrication reactor. Credit: Authors / Aalto University

It’s a very ‘carbony’ time: graphene jacket, graphene-skinned airplane, and schwarzite

In August 2018, I been stumbled across several stories about graphene-based products and a new form of carbon.

Graphene jacket

The company producing this jacket has as its goal “… creating bionic clothing that is both bulletproof and intelligent.” Well, ‘bionic‘ means biologically-inspired engineering and ‘intelligent‘ usually means there’s some kind of computing capability in the product. This jacket, which is the first step towards the company’s goal, is not bionic, bulletproof, or intelligent. Nonetheless, it represents a very interesting science experiment in which you, the consumer, are part of step two in the company’s R&D (research and development).

Onto Vollebak’s graphene jacket,

Courtesy: Vollebak

From an August 14, 2018 article by Jesus Diaz for Fast Company,

Graphene is the thinnest possible form of graphite, which you can find in your everyday pencil. It’s purely bi-dimensional, a single layer of carbon atoms that has unbelievable properties that have long threatened to revolutionize everything from aerospace engineering to medicine. …

Despite its immense promise, graphene still hasn’t found much use in consumer products, thanks to the fact that it’s hard to manipulate and manufacture in industrial quantities. The process of developing Vollebak’s jacket, according to the company’s cofounders, brothers Steve and Nick Tidball, took years of intensive research, during which the company worked with the same material scientists who built Michael Phelps’ 2008 Olympic Speedo swimsuit (which was famously banned for shattering records at the event).

The jacket is made out of a two-sided material, which the company invented during the extensive R&D process. The graphene side looks gunmetal gray, while the flipside appears matte black. To create it, the scientists turned raw graphite into something called graphene “nanoplatelets,” which are stacks of graphene that were then blended with polyurethane to create a membrane. That, in turn, is bonded to nylon to form the other side of the material, which Vollebak says alters the properties of the nylon itself. “Adding graphene to the nylon fundamentally changes its mechanical and chemical properties–a nylon fabric that couldn’t naturally conduct heat or energy, for instance, now can,” the company claims.

The company says that it’s reversible so you can enjoy graphene’s properties in different ways as the material interacts with either your skin or the world around you. “As physicists at the Max Planck Institute revealed, graphene challenges the fundamental laws of heat conduction, which means your jacket will not only conduct the heat from your body around itself to equalize your skin temperature and increase it, but the jacket can also theoretically store an unlimited amount of heat, which means it can work like a radiator,” Tidball explains.

He means it literally. You can leave the jacket out in the sun, or on another source of warmth, as it absorbs heat. Then, the company explains on its website, “If you then turn it inside out and wear the graphene next to your skin, it acts like a radiator, retaining its heat and spreading it around your body. The effect can be visibly demonstrated by placing your hand on the fabric, taking it away and then shooting the jacket with a thermal imaging camera. The heat of the handprint stays long after the hand has left.”

There’s a lot more to the article although it does feature some hype and I’m not sure I believe Diaz’s claim (August 14, 2018 article) that ‘graphene-based’ hair dye is perfectly safe ( Note: A link has been removed),

Graphene is the thinnest possible form of graphite, which you can find in your everyday pencil. It’s purely bi-dimensional, a single layer of carbon atoms that has unbelievable properties that will one day revolutionize everything from aerospace engineering to medicine. Its diverse uses are seemingly endless: It can stop a bullet if you add enough layers. It can change the color of your hair with no adverse effects. [emphasis mine] It can turn the walls of your home into a giant fire detector. “It’s so strong and so stretchy that the fibers of a spider web coated in graphene could catch a falling plane,” as Vollebak puts it in its marketing materials.

Not unless things have changed greatly since March 2018. My August 2, 2018 posting featured the graphene-based hair dye announcement from March 2018 and a cautionary note from Dr. Andrew Maynard (scroll down ab out 50% of the way for a longer excerpt of Maynard’s comments),

Northwestern University’s press release proudly announced, “Graphene finds new application as nontoxic, anti-static hair dye.” The announcement spawned headlines like “Enough with the toxic hair dyes. We could use graphene instead,” and “’Miracle material’ graphene used to create the ultimate hair dye.”

From these headlines, you might be forgiven for getting the idea that the safety of graphene-based hair dyes is a done deal. Yet having studied the potential health and environmental impacts of engineered nanomaterials for more years than I care to remember, I find such overly optimistic pronouncements worrying – especially when they’re not backed up by clear evidence.

These studies need to be approached with care, as the precise risks of graphene exposure will depend on how the material is used, how exposure occurs and how much of it is encountered. Yet there’s sufficient evidence to suggest that this substance should be used with caution – especially where there’s a high chance of exposure or that it could be released into the environment.

The full text of Dr. Maynard’s comments about graphene hair dyes and risk can be found here.

Bearing in mind  that graphene-based hair dye is an entirely different class of product from the jacket, I wouldn’t necessarily dismiss risks; I would like to know what kind of risk assessment and safety testing has been done. Due to their understandable enthusiasm, the brothers Tidball have focused all their marketing on the benefits and the opportunity for the consumer to test their product (from graphene jacket product webpage),

While it’s completely invisible and only a single atom thick, graphene is the lightest, strongest, most conductive material ever discovered, and has the same potential to change life on Earth as stone, bronze and iron once did. But it remains difficult to work with, extremely expensive to produce at scale, and lives mostly in pioneering research labs. So following in the footsteps of the scientists who discovered it through their own highly speculative experiments, we’re releasing graphene-coated jackets into the world as experimental prototypes. Our aim is to open up our R&D and accelerate discovery by getting graphene out of the lab and into the field so that we can harness the collective power of early adopters as a test group. No-one yet knows the true limits of what graphene can do, so the first edition of the Graphene Jacket is fully reversible with one side coated in graphene and the other side not. If you’d like to take part in the next stage of this supermaterial’s history, the experiment is now open. You can now buy it, test it and tell us about it. [emphasis mine]

How maverick experiments won the Nobel Prize

While graphene’s existence was first theorised in the 1940s, it wasn’t until 2004 that two maverick scientists, Andre Geim and Konstantin Novoselov, were able to isolate and test it. Through highly speculative and unfunded experimentation known as their ‘Friday night experiments,’ they peeled layer after layer off a shaving of graphite using Scotch tape until they produced a sample of graphene just one atom thick. After similarly leftfield thinking won Geim the 2000 Ig Nobel prize for levitating frogs using magnets, the pair won the Nobel prize in 2010 for the isolation of graphene.

Should you be interested, in beta-testing the jacket, it will cost you $695 (presumably USD); order here. One last thing, Vollebak is based in the UK.

Graphene skinned plane

An August 14, 2018 news item (also published as an August 1, 2018 Haydale press release) by Sue Keighley on Azonano heralds a new technology for airplans,

Haydale, (AIM: HAYD), the global advanced materials group, notes the announcement made yesterday from the University of Central Lancashire (UCLAN) about the recent unveiling of the world’s first graphene skinned plane at the internationally renowned Farnborough air show.

The prepreg material, developed by Haydale, has potential value for fuselage and wing surfaces in larger scale aero and space applications especially for the rapidly expanding drone market and, in the longer term, the commercial aerospace sector. By incorporating functionalised nanoparticles into epoxy resins, the electrical conductivity of fibre-reinforced composites has been significantly improved for lightning-strike protection, thereby achieving substantial weight saving and removing some manufacturing complexities.

Before getting to the photo, here’s a definition for pre-preg from its Wikipedia entry (Note: Links have been removed),

Pre-preg is “pre-impregnated” composite fibers where a thermoset polymer matrix material, such as epoxy, or a thermoplastic resin is already present. The fibers often take the form of a weave and the matrix is used to bond them together and to other components during manufacture.

Haydale has supplied graphene enhanced prepreg material for Juno, a three-metre wide graphene-enhanced composite skinned aircraft, that was revealed as part of the ‘Futures Day’ at Farnborough Air Show 2018. [downloaded from https://www.azonano.com/news.aspx?newsID=36298]

A July 31, 2018 University of Central Lancashire (UCLan) press release provides a tiny bit more (pun intended) detail,

The University of Central Lancashire (UCLan) has unveiled the world’s first graphene skinned plane at an internationally renowned air show.

Juno, a three-and-a-half-metre wide graphene skinned aircraft, was revealed on the North West Aerospace Alliance (NWAA) stand as part of the ‘Futures Day’ at Farnborough Air Show 2018.

The University’s aerospace engineering team has worked in partnership with the Sheffield Advanced Manufacturing Research Centre (AMRC), the University of Manchester’s National Graphene Institute (NGI), Haydale Graphene Industries (Haydale) and a range of other businesses to develop the unmanned aerial vehicle (UAV), which also includes graphene batteries and 3D printed parts.

Billy Beggs, UCLan’s Engineering Innovation Manager, said: “The industry reaction to Juno at Farnborough was superb with many positive comments about the work we’re doing. Having Juno at one the world’s biggest air shows demonstrates the great strides we’re making in leading a programme to accelerate the uptake of graphene and other nano-materials into industry.

“The programme supports the objectives of the UK Industrial Strategy and the University’s Engineering Innovation Centre (EIC) to increase industry relevant research and applications linked to key local specialisms. Given that Lancashire represents the fourth largest aerospace cluster in the world, there is perhaps no better place to be developing next generation technologies for the UK aerospace industry.”

Previous graphene developments at UCLan have included the world’s first flight of a graphene skinned wing and the launch of a specially designed graphene-enhanced capsule into near space using high altitude balloons.

UCLan engineering students have been involved in the hands-on project, helping build Juno on the Preston Campus.

Haydale supplied much of the material and all the graphene used in the aircraft. Ray Gibbs, Chief Executive Officer, said: “We are delighted to be part of the project team. Juno has highlighted the capability and benefit of using graphene to meet key issues faced by the market, such as reducing weight to increase range and payload, defeating lightning strike and protecting aircraft skins against ice build-up.”

David Bailey Chief Executive of the North West Aerospace Alliance added: “The North West aerospace cluster contributes over £7 billion to the UK economy, accounting for one quarter of the UK aerospace turnover. It is essential that the sector continues to develop next generation technologies so that it can help the UK retain its competitive advantage. It has been a pleasure to support the Engineering Innovation Centre team at the University in developing the world’s first full graphene skinned aircraft.”

The Juno project team represents the latest phase in a long-term strategic partnership between the University and a range of organisations. The partnership is expected to go from strength to strength following the opening of the £32m EIC facility in February 2019.

The next step is to fly Juno and conduct further tests over the next two months.

Next item, a new carbon material.

Schwarzite

I love watching this gif of a schwarzite,

The three-dimensional cage structure of a schwarzite that was formed inside the pores of a zeolite. (Graphics by Yongjin Lee and Efrem Braun)

An August 13, 2018 news item on Nanowerk announces the new carbon structure,

The discovery of buckyballs [also known as fullerenes, C60, or buckminsterfullerenes] surprised and delighted chemists in the 1980s, nanotubes jazzed physicists in the 1990s, and graphene charged up materials scientists in the 2000s, but one nanoscale carbon structure – a negatively curved surface called a schwarzite – has eluded everyone. Until now.

University of California, Berkeley [UC Berkeley], chemists have proved that three carbon structures recently created by scientists in South Korea and Japan are in fact the long-sought schwarzites, which researchers predict will have unique electrical and storage properties like those now being discovered in buckminsterfullerenes (buckyballs or fullerenes for short), nanotubes and graphene.

An August 13, 2018 UC Berkeley news release by Robert Sanders, which originated the news item, describes how the Berkeley scientists and the members of their international  collaboration from Germany, Switzerland, Russia, and Italy, have contributed to the current state of schwarzite research,

The new structures were built inside the pores of zeolites, crystalline forms of silicon dioxide – sand – more commonly used as water softeners in laundry detergents and to catalytically crack petroleum into gasoline. Called zeolite-templated carbons (ZTC), the structures were being investigated for possible interesting properties, though the creators were unaware of their identity as schwarzites, which theoretical chemists have worked on for decades.

Based on this theoretical work, chemists predict that schwarzites will have unique electronic, magnetic and optical properties that would make them useful as supercapacitors, battery electrodes and catalysts, and with large internal spaces ideal for gas storage and separation.

UC Berkeley postdoctoral fellow Efrem Braun and his colleagues identified these ZTC materials as schwarzites based of their negative curvature, and developed a way to predict which zeolites can be used to make schwarzites and which can’t.

“We now have the recipe for how to make these structures, which is important because, if we can make them, we can explore their behavior, which we are working hard to do now,” said Berend Smit, an adjunct professor of chemical and biomolecular engineering at UC Berkeley and an expert on porous materials such as zeolites and metal-organic frameworks.

Smit, the paper’s corresponding author, Braun and their colleagues in Switzerland, China, Germany, Italy and Russia will report their discovery this week in the journal Proceedings of the National Academy of Sciences. Smit is also a faculty scientist at Lawrence Berkeley National Laboratory.

Playing with carbon

Diamond and graphite are well-known three-dimensional crystalline arrangements of pure carbon, but carbon atoms can also form two-dimensional “crystals” — hexagonal arrangements patterned like chicken wire. Graphene is one such arrangement: a flat sheet of carbon atoms that is not only the strongest material on Earth, but also has a high electrical conductivity that makes it a promising component of electronic devices.

schwarzite carbon cage

The cage structure of a schwarzite that was formed inside the pores of a zeolite. The zeolite is subsequently dissolved to release the new material. (Graphics by Yongjin Lee and Efrem Braun)

Graphene sheets can be wadded up to form soccer ball-shaped fullerenes – spherical carbon cages that can store molecules and are being used today to deliver drugs and genes into the body. Rolling graphene into a cylinder yields fullerenes called nanotubes, which are being explored today as highly conductive wires in electronics and storage vessels for gases like hydrogen and carbon dioxide. All of these are submicroscopic, 10,000 times smaller than the width of a human hair.

To date, however, only positively curved fullerenes and graphene, which has zero curvature, have been synthesized, feats rewarded by Nobel Prizes in 1996 and 2010, respectively.

In the 1880s, German physicist Hermann Schwarz investigated negatively curved structures that resemble soap-bubble surfaces, and when theoretical work on carbon cage molecules ramped up in the 1990s, Schwarz’s name became attached to the hypothetical negatively curved carbon sheets.

“The experimental validation of schwarzites thus completes the triumvirate of possible curvatures to graphene; positively curved, flat, and now negatively curved,” Braun added.

Minimize me

Like soap bubbles on wire frames, schwarzites are topologically minimal surfaces. When made inside a zeolite, a vapor of carbon-containing molecules is injected, allowing the carbon to assemble into a two-dimensional graphene-like sheet lining the walls of the pores in the zeolite. The surface is stretched tautly to minimize its area, which makes all the surfaces curve negatively, like a saddle. The zeolite is then dissolved, leaving behind the schwarzite.

soap bubble schwarzite structure

A computer-rendered negatively curved soap bubble that exhibits the geometry of a carbon schwarzite. (Felix Knöppel image)

“These negatively-curved carbons have been very hard to synthesize on their own, but it turns out that you can grow the carbon film catalytically at the surface of a zeolite,” Braun said. “But the schwarzites synthesized to date have been made by choosing zeolite templates through trial and error. We provide very simple instructions you can follow to rationally make schwarzites and we show that, by choosing the right zeolite, you can tune schwarzites to optimize the properties you want.”

Researchers should be able to pack unusually large amounts of electrical charge into schwarzites, which would make them better capacitors than conventional ones used today in electronics. Their large interior volume would also allow storage of atoms and molecules, which is also being explored with fullerenes and nanotubes. And their large surface area, equivalent to the surface areas of the zeolites they’re grown in, could make them as versatile as zeolites for catalyzing reactions in the petroleum and natural gas industries.

Braun modeled ZTC structures computationally using the known structures of zeolites, and worked with topological mathematician Senja Barthel of the École Polytechnique Fédérale de Lausanne in Sion, Switzerland, to determine which of the minimal surfaces the structures resembled.

The team determined that, of the approximately 200 zeolites created to date, only 15 can be used as a template to make schwarzites, and only three of them have been used to date to produce schwarzite ZTCs. Over a million zeolite structures have been predicted, however, so there could be many more possible schwarzite carbon structures made using the zeolite-templating method.

Other co-authors of the paper are Yongjin Lee, Seyed Mohamad Moosavi and Barthel of the École Polytechnique Fédérale de Lausanne, Rocio Mercado of UC Berkeley, Igor Baburin of the Technische Universität Dresden in Germany and Davide Proserpio of the Università degli Studi di Milano in Italy and Samara State Technical University in Russia.

Here’s a link to and a citation for the paper,

Generating carbon schwarzites via zeolite-templating by Efrem Braun, Yongjin Lee, Seyed Mohamad Moosavi, Senja Barthel, Rocio Mercado, Igor A. Baburin, Davide M. Proserpio, and Berend Smit. PNAS August 14, 2018. 201805062; published ahead of print August 14, 2018. https://doi.org/10.1073/pnas.1805062115

This paper appears to be open access.

An artistic feud over the blackest black (a coating material)

This artistic feud has its roots in a nanotechnology-enabled coating material known as Vantablack. Surrey Nanosystems in the UK sent me an announcement which I featured here in a March 14, 2016 posting. About one month later (in an April 16, 2016 posting regarding risks and an artistic controversy), I recounted the story of the controversy, which resulted from the company’s exclusive deal with artist, Sir Anish Kapoor (scroll down the post about 60% of the way to ‘Anish Kapoor and his exclusive rights to Vantablack’.

Apparently, the controversy led to an artistic feud between artists Stuart Semple and Kapoor. Outraged by the notion that only Kapoor could have access to the world’s blackest black, Semple created the world’s pinkest pink and stipulated that any artist in the world could have access to this colour—except Anish Kapoor.

Kapoor’s response can seen in a January 30,2019 article by Sarah Cascone for artnet.com,

… Semple started selling what he called “the world’s pinkest pink, available to anyone who wasn’t Kapoor.”

“I wanted to make a point about elitism and self-expression and the fact that everybody should be able to make art,” Semple said. But within weeks, “tragedy struck. Anish Kapoor got our pink! And he dipped his middle finger in it and put a picture on Instagram!”

[downloaded from http://www.artlyst.com/wp-content/uploads/2016/10/anish-kapoor-pink-1200x600_c.jpg]

Cascone’s article, which explores the history of the feud in greater detail also announces the latest installment (Note: Links have been removed),

In the battle over artistic access to the world’s blackest blacks, Stuart Semple isn’t backing down. The British artist, who took exception to Anish Kapoor’s exclusive contract to use Vantablack, the world’s blackest black substance, just launched a Kickstarter to produce a super dark paint of his own—and it has now been fully funded.

Jesus Diaz’s February 1, 2019 article for Fast Company provides some general technical details (Note: A link has been removed),

… Semple decided to team up with paint makers and about 1,000 artists to develop and test a competitor to Vantablack. His first version, Black 2.0, wasn’t quite as black as Vantablack, since it only absorbed 95% of the visible light (Vantablack absorbs about 99%).

Now, Black 3.0 is out and available on Kickstarter for about $32 per 150ml tube. According to Semple, it is the blackest, mattest, flattest acrylic paint available on the planet, capturing up to 99% of all the visible spectrum radiation. The paint is based on a new pigment called Black Magick, whose exact composition they aren’t disclosing. Black 3.0 is made up of this pigment, combined with a custom acrylic polymer. Semple and his colleagues claim that the polymer “is special because it has more available bonds than any other acrylic polymer being used in paints,” allowing more pigment density. The paint is then finished with what they claim are new “nano-mattifiers,” which remove any shine from the paint. Unlike Vantablack, the resulting paint is soluble in water and nontoxic. [emphasis mine]

I wonder what a ‘nano-mattifier’ might be. Regardless, I’m glad to see this new black is (with a nod to my April 16, 2016 posting about risks and this artistic controversy) nontoxic.

Semple’s ‘blackest black paint’ Kickstarter campaign can be found here. It ends on March 22, 2019 at 1:01 am PDT. The goal is $42,755 in Canadian dollars (CAD) and, as Iwrite this, they currently have $473,062 CAD in pledges.

I don’t usually embed videos that run over 5 mins. but Stuart Semple is very appealing in at least two senses of the word,

Spider glue

Caption: An orb spider, glue-maker extraordinaire, at work on a web. Credit: The University of Akron

Scientists are taking inspiration from spiders in their quest to develop better adhesives. (Are they abandoning the gecko? Usually when scientists study adhesiveness, there’s talk of geckos. From a June 5, 2018 news item on ScienceDaily,

Ever wonder why paint peels off the wall during summer’s high humidity? It’s the same reason that bandages separate from skin when we bathe or swim.

Interfacial water, as it’s known, forms a slippery and non-adhesive layer between the glue and the surface to which it is meant to stick, interfering with the formation of adhesive bonds between the two.

Overcoming the effects of interfacial water is one of the challenges facing developers of commercial adhesives.

To find a solution, researchers at The University of Akron (UA) are looking to one of the strongest materials found in nature: spider silk.

The sticky glue that coats the silk threads of spider webs is a hydrogel, meaning it is full of water. One would think, then, that spiders would have difficulty catching prey, especially in humid conditions — but they do not. In fact, their sticky glue, which has been a subject of intensive research for years, is one of the most effective biological glues in all of nature.

A June 4, 2018 University of Akron news release (also on EurekAlert published on June 5, 2018), which originated the news item, provides more detail,

So how is spider glue able to stick in highly humid conditions?

That question was the subject of investigation by UA graduate students Saranshu Singla, Gaurav Amarpuri and Nishad Dhopatkar, who have been working with Dr. Ali Dhinojwala, interim dean of the College of Polymer Science and Polymer Engineering, and Dr. Todd Blackledge, professor of biology in the Integrated Bioscience program. Both professors are principal investigators in UA’s Biomimicry Research Innovation Center [BRIC], which specializes in emulating biological forms, processes, patterns and systems to solve technical challenges.

The team’s findings, which may provide the clue to developing stronger commercial adhesives, can be read in a paper recently published in the journal Nature Communications.

Singla and her colleagues set out to examine the secret behind the success of the common orb spider (Larinioides cornutus) glue and uncover how it overcomes the primary obstacle of achieving good adhesion in the humid conditions where water could be present between the glue and the target surface.

To investigate the processes involved, the team took orb spider glue, set it on sapphire substrate, then examined it using a combination of interface-sensitive spectroscopy and infrared spectroscopy.

Spider glue is made of three elements: two specialized glycoproteins, a collection of low molecular mass organic and inorganic compounds (LMMCs), and water. The LMMCs are hygroscopic (water-attracting), which keeps the glue soft and tacky to stick.

Singla and her team discovered that these glycoproteins act as primary binding agents to the surface. Glycoprotein-based glues have been identified in several other biological glues, such as fungi, algae, diatoms, sea stars, sticklebacks and English ivy.

But why doesn’t the water present in the spider glue interfere with the adhesive contact the way it does with most synthetic adhesives?

The LMMCs, the team concluded, perform a previously unknown function of sequestering interfacial water, preventing adhesive failure.

Singla and colleagues determined that it is the interaction of glycoproteins and LMMCs that governs the adhesive quality of the glue produced, with the respective proportions varying across species, thus optimizing adhesive strength to match the relative humidity of spider habitat.

“The hygroscopic compounds – known as water-absorbers – in spider glue play a previously unknown role in moving water away from the boundary, thereby preventing failure of spider glue at high humidity,” explained Singla.

The ability of the spider glue to overcome the problem of interfacial water by effectively absorbing it is the key finding of the research, and the one with perhaps the strongest prospect for commercial development.

“Imagine a paint that is guaranteed for life, come rain or shine,” Singla remarked.

All thanks to your friendly neighborhood spider glue.

Here’s a link to and a citation for the paper,

Hygroscopic compounds in spider aggregate glue remove interfacial water to maintain adhesion in humid conditions by Saranshu Singla, Gaurav Amarpuri, Nishad Dhopatkar, Todd A. Blackledge, & Ali Dhinojwala. Nature Communicationsvolume 9, Article number: 1890 (2018) Published 22 May 2018 DOI: https://doi.org/10.1038/s41467-018-04263-z

This paper is open access.