Tag Archives: glass

Foldable glass (well, there’s some plastic too)

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Michael Berger has written a fascinating Aug. 11, 2015 Nanowerk Spotlight article on folding glass,

Have you ever heard about foldable glass?

Exactly.

Glass is notorious for its brittleness. Although industry has developed ultra-thin (∼0.1 mm), flexible glass (like Corning’s Willow® Glass) that can be bent for applications liked curved TV and smartphone displays, fully foldable glass had not been demonstrated. Until now.

…

Khang [Dahl-Young Khang, an Associate Professor in the Department of Materials Science and Engineering at Yonsei University] and his group have now demonstrated substrate platforms of glass and plastics, which can be reversibly and repeatedly foldable at pre designed location(s) without any mechanical failure or deterioration in device performances.

…

“We have engineered the substrates to have thinned parts on which the folding deformation should occur,” Moon Jong Han, first author of the paper a graduate student in Khang’s lab, says. “This localizes the deformation strain on those thinned parts only.”

He adds that this approach to engineering substrates has another advantage regarding device materials: “There is no need to adopt any novel materials such as nanowires, carbon nanotubes, graphene, etc. Rather, all the conventional materials that have been used for high-performance devices can be directly applied on our engineered substrates.”

Intriguingly, even ITO (indium tin oxide), a very brittle transparent conducting oxide, can be used as electrode on this novel foldable glass platform.

What makes the approach especially intriguing is the ability to reverse the fold and that it doesn’t require special nanomaterials, such as carbon nanotubes, etc. From Berger’s Aug. 11, 2015 article,

The width of the thinned parts, the gap width, plays the key role in implementing dual foldability. The other key element is the asymmetric design of the gap width for the second folding.

The researchers achieved foldability, in part, by copying a technique used for folding mats and oriental hinge-less screens which have thinned areas to allow folding.

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

Glass and Plastics Platforms for Foldable Electronics and Displays by Moon Jung Han and Dahl-Young Khang. Advanced Materials DOI: 10.1002/adma.201501060 First published: 21 July 2015

This paper is behind a paywall.

Berger’s article is not only fascinating, it is also illustrated with some images provided by the researchers.

Lightning strikes to create glass (reshaping rock at the atomic level)

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This features glass (more specifically glass tubes), one of my interests, and it’s a fascinating story. From an Aug. 6, 2015 news item on Azonano,

At a rock outcropping in southern France, a jagged fracture runs along the granite. The surface in and around the crevice is discolored black, as if wet or covered in algae.

But, according to a new paper coauthored by the University of Pennsylvania’s Reto Gieré, the real explanation for the rock’s unusual features is more dramatic: a powerful bolt of lightning.

Here’s what the rock looks like afterwards,

A rock fulgurite revealed that lightning strikes alter quartz's crystal structure on the atomic level. Courtesy: Penn State

A rock fulgurite revealed that lightning strikes alter quartz’s crystal structure on the atomic level. Courtesy: University of Pennsylvania

The researchers have also provided an image taken under an transmission electron microscope,

Gieré and colleagues observed the parallel lines of shock lamellae under a transmission electron microscope Courtesy: Penn State

Gieré and colleagues observed the parallel lines of shock lamellae under a transmission electron microscope Courtesy: University of Pennsylvania

An Aug. 5, 2015 University of Pennsylvania news release, which originated the news item, provides more technical details about the research,

Using extremely high-resolution microscopy, Gieré, professor and chair of the Department of Earth and Environmental Science in Penn’s School of Arts & Sciences, and his coauthors found that not only had the lightning melted the rock’s surface, resulting in a distinctive black “glaze,” but had transferred enough pressure to deform a thin layer of quartz crystals beneath the surface, resulting in distinct atomic-level structures called shock lamellae.

Prior to this study, the only natural events known to create this type of lamellae were meteorite impacts.

“I think the most exciting thing about this study is just to see what lightning can do,” Gieré said. “To see that lightning literally melts the surface of a rock and changes crystal structures, to me, is fascinating.”

Gieré said the finding serves as a reminder to geologists not to rush to interpret shock lamellae as indicators of a meteorite strike.

“Most geologists are careful; they don’t just use one observation,” he said, “But this is a good reminder to always use multiple observations to draw big conclusions, that there are multiple mechanisms that can result in a similar effect.”

Gieré collaborated on the study with Wolfhard Wimmenauer and Hiltrud Müller-Sigmund of Albert-Ludwigs-Universität, Richard Wirth of GeoForschungsZentrum Potsdam and Gregory R. Lumpkin and Katherine L. Smith of the Australian Nuclear Science and Technology Organization.

The paper was published in the journal American Mineralogist.

Geologists have long known that lightning, through rapid increases in temperature as well as physical and chemical effects, can alter sediments. When it strikes sand, for example, lightning melts the grains, which fuse and form glass tubes known as fulgurites.

Fulgurites can also form when lightning strikes other materials, including rock and soil. The current study examined a rock fulgurite found near Les Pradals, France. Gieré and colleagues took samples from the rock, then cut thin sections and polished them.

Under an optical microscope, they found that the outer black layer — the fulgurite itself — appeared shiny, “almost like a ceramic glaze,” Gieré said.

The layer was also porous, almost like a foam, due to the lightning’s heat vaporizing the rock’s surface. A chemical analysis of the fulgurite layer turned up elevated levels of sulfur dioxide and phosphorous pentoxide, which the researchers believe may have derived from lichen living on the rock’s surface at the time of the lightning strike.

The team further studied the samples using a transmission electron microscope, which allows users to examine specimens at the atomic level. This revealed that the fulgurite lacked any crystalline structure, consistent with it representing a melt formed through the high heat from the lightning strike.

But, in a layer of the sample immediately adjacent to the fulgurite, slightly deeper in the rock, the researchers spotted an unusual feature: a set of straight, parallel lines known as shock lamellae. This feature occurs when the crystal structure of quartz or other minerals deform in response to a vast wave of pressure.

“It’s like if someone pushes you, you rearrange your body to be comfortable,” Gieré said. “The mineral does the same thing.”

The lamellae were present in a layer of the rock only about three micrometers wide, indicating that the energy of the lightning bolt’s impact dissipated over that distance.

This characteristic deformation of crystals had previously only been seen in minerals from sites where meteorites struck. Shock lamellae are believed to form at pressures up to more than 10 gigapascals, or with 20 million times greater force than a boxer’s punch.

Gieré and colleagues hope to study rock fulgurites from other sites to understand the physical and chemical effects of lightning bolts on rocks in greater detail.

Another takeaway for geologists, rock climbers and hikers who spend time on rocks in high, exposed places is to beware when they see the tell-tale shiny black glaze of a rock fulgurite, as it might indicate a site prone to lightning strikes.

“Once it was pointed out to me, I started seeing it again and again,” he said. “I’ve had some close calls with thunderstorms in the field, where I’ve had to throw down my metal instruments and run.”

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

Lightning-induced shock lamellae in quartz by Reto Gieré, Wolfhard Wimmenauer, Hiltrud Müller-Sigmund, Richard Wirth, Gregory R. Lumpkin, and Katherine L. Smith. American Mineralogist, July 2015 v. 100 no. 7 p. 1645-1648 doi: 10.2138/am-2015-5218

This paper is behind a paywall.

Mystery of glass—shattered and Happy Canada Day!

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I’m pretty sure I’ve said this before but a repetition can’t hurt, “I love glass both for the art and the mystery.” Naturally, I am of two minds about this ‘shattered’ glass mystery from the University of Waterloo (Canada).

A June 29, 2015 University of Waterloo news release (also on EurekAlert) provides a teasing (for impatient people like me) introduction before describing the solution to the mystery,

A physicist at the University of Waterloo is among a team of scientists who have described how glasses form at the molecular level and provided a possible solution to a problem that has stumped scientists for decades.

Their simple theory is expected to open up the study of glasses to non-experts and undergraduates as well as inspire breakthroughs in novel nanomaterials.

The paper published by physicists from the University of Waterloo, McMaster University, ESPCI ParisTech and Université Paris Diderot appeared in the prestigious peer-reviewed journal, Proceedings of the National Academy of Sciences (PNAS).

Glasses are much more than silicon-based materials in bottles and windows. In fact, any solid without an ordered, crystalline structure — metal, plastic, a polymer — that forms a molten liquid when heated above a certain temperature is a glass. Glasses are an essential material in technology, pharmaceuticals, housing, renewable energy and increasingly nano electronics.

“We were surprised — delighted — that the model turned out to be so simple,” said author James Forrest, a University Research Chair and professor in the Faculty of Science. “We were convinced it had already been published.”

The theory relies on two basic concepts: molecular crowding and string-like co-operative movement. [emphasis mine] Molecular crowding describes how molecules within glasses move like people in a crowded room. As the number of people increase, the amount of free volume decreases and the slower people can move through the crowd. Those people next to the door are able to move more freely, just as the surfaces of glasses never actually stop flowing, even at lower temperatures.

The more crowded the room, the more you rely on the co-operative movement with your neighbours to get where you’re going. Likewise, individual molecules within a glass aren’t able to move totally freely. They move with, yet are confined by, strings of weak molecular bonds with their neighbours.

Theories of crowding and cooperative movement are decades old. This is the first time scientists combined both theories to describe how a liquid turns into a glass.

“Research on glasses is normally reserved for specialists in condensed matter physics,” said Forrest, who is also an associate faculty member at Perimeter Institute for Theoretical Physics and a member of the Waterloo Institute for Nanotechnology.  “Now a whole new generation of scientists can study and apply glasses just using first-year calculus.”

Their theory successfully predicts everything from bulk behaviour to surface flow to the once-elusive phenomenon of the glass transition itself. Forrest and colleagues worked for 20 years to bring theory in agreement with decades of observation on glassy materials.

An accurate theory becomes particularly important when trying to understand glass dynamics at the nanoscale. This finding has implications for developing and manufacturing new nanomaterials, such as glasses with conductive properties, or even calculating the uptake of glassy forms of pharmaceuticals.

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

Cooperative strings and glassy interfaces by Thomas Salez, Justin Salez, Kari Dalnoki-Veress, Elie Raphaël, and James A. Forrest. PNAS (Proceedings of the National Academy of Sciences) Published online before print June 22, 2015, doi: 10.1073/pnas.1503133112

This paper is behind a paywall.

Finally and again, Happy Canada Day!

Glasswing butterflies teach us about reflection

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Contrary to other transparent surfaces, the wings of the glasswing butterfly (Greta Oto) hardly reflect any light. Lenses or displays of mobiles might profit from the investigation of this phenomenon. (Photo: Radwanul Hasan Siddique, KIT)

Contrary to other transparent surfaces, the wings of the glasswing butterfly (Greta Oto) hardly reflect any light. Lenses or displays of mobiles might profit from the investigation of this phenomenon. (Photo: Radwanul Hasan Siddique, KIT)

I wouldn’t have really believed. Other than glass, I’ve never seen anything in nature that’s as transparent and distortion-free as this butterfly’s wings.

An April 22, 2015 news item on ScienceDaily provides more information about the butterfly,

The effect is known from the smart phone: Sun is reflected by the display and hardly anything can be seen. In contrast to this, the glasswing butterfly hardly reflects any light in spite of its transparent wings. As a result, it is difficult for predatory birds to track the butterfly during the flight. Researchers of KIT under the direction of Hendrik Hölscher found that irregular nanostructures on the surface of the butterfly wing cause the low reflection. In theoretical experiments, they succeeded in reproducing the effect that opens up fascinating application options, e.g. for displays of mobile phones or laptops.

An April 22, 2015 Karlsruhe Institute of Technology (KIT) press release (also on EurekAlert), which originated the news item, explains the scientific interest,

Transparent materials such as glass, always reflect part of the incident light. Some animals with transparent surfaces, such as the moth with its eyes, succeed in keeping the reflections small, but only when the view angle is vertical to the surface. The wings of the glasswing butterfly that lives mainly in Central America, however, also have a very low reflection when looking onto them under higher angles. Depending on the view angle, specular reflection varies between two and five percent. For comparison: As a function of the view angle, a flat glass plane reflects between eight and 100 percent, i.e. reflection exceeds that of the butterfly wing by several factors. Interestingly, the butterfly wing does not only exhibit a low reflection of the light spectrum visible to humans, but also suppresses the infrared and ultraviolet radiation that can be perceived by animals. This is important to the survival of the butterfly.

For research into this so far unstudied phenomenon, the scientists examined glasswings by scanning electron microscopy. Earlier studies revealed that regular pillar-like nanostructures are responsible for the low reflections of other animals. The scientists now also found nanopillars on the butterfly wings. In contrast to previous findings, however, they are arranged irregularly and feature a random height. Typical height of the pillars varies between 400 and 600 nanometers, the distance of the pillars ranges between 100 and 140 nanometers. This corresponds to about one thousandth of a human hair.

In simulations, the researchers mathematically modeled this irregularity of the nanopillars in height and arrangement. They found that the calculated reflected amount of light exactly corresponds to the observed amount at variable view angles. In this way, they proved that the low reflection at variable view angles is caused by this irregularity of the nanopillars. Hölscher’s doctoral student Radwanul Hasan Siddique, who discovered this effect, considers the glasswing butterfly a fascinating animal: “Not only optically with its transparent wings, but also scientifically. In contrast to other natural phenomena, where regularity is of top priority, the glasswing butterfly uses an apparent chaos to reach effects that are also fascinating for us humans.”

The findings open up a range of applications wherever low-reflection surfaces are needed, for lenses or displays of mobile phones, for instance. Apart from theoretical studies of the phenomenon, the infrastructure of the Institute of Microstructure Technology also allows for practical implementation. First application tests are in the conception phase at the moment. Prototype experiments, however, already revealed that this type of surface coating also has a water-repellent and self-cleaning effect.

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

The role of random nanostructures for the omnidirectional anti-reflection properties of the glasswing butterfly by Radwanul Hasan Siddique, Guillaume Gomard, & Hendrik Hölscher. Nature Communications 6, Article number: 6909 doi:10.1038/ncomms7909 Published 22 April 2015

The paper is behind a paywall but there is a free preview via ReadCube Access.

Venus’* flower basket sea sponge has strength

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Despite being made essentially of glass, the skeleton of the sea sponge known as Venus' flower basket is remarkably strong -- right down to the tiny, hair-like fibers that hold the creatures to the sea floor. Researchers from Brown University have shown that those fibers, called spicules, have an intricate internal structure that is fine-tuned to boost strength. The findings could inform the engineering of human-made materials. Credit: Kesari Lab / Brown University

Despite being made essentially of glass, the skeleton of the sea sponge known as Venus’ flower basket is remarkably strong — right down to the tiny, hair-like fibers that hold the creatures to the sea floor. Researchers from Brown University have shown that those fibers, called spicules, have an intricate internal structure that is fine-tuned to boost strength. The findings could inform the engineering of human-made materials.
Credit: Kesari Lab / Brown University

I’m not sure how anyone saw a flower basket in that sponge but I bow to a more poetic soul. In any event, scientists at Brown University (US) have shown that this sponge has unexpected strength according to an April 6, 2015 news item on ScienceDaily,

Life may seem precarious for the sea sponge known as Venus’ flower basket. Tiny, hair-like appendages made essentially of glass are all that hold the creatures to their seafloor homes. But fear not for these creatures of the deep. Those tiny lifelines, called basalia spicules, are fine-tuned for strength, according to new research led by Brown University engineers.

In a paper published in the Proceedings of the National Academy of Sciences, the researchers show that the secret to spicules’ strength lies in their remarkable internal structure. The spicules, each only 50 microns in diameter, are made of a silica (glass) core surrounded by 10 to 50 concentric cylinders of glass, each separated by an ultra-thin layer of an organic material. The walls of each cylinder gradually decrease in thickness moving from the core toward the outside edge of the spicule.

An April 6, 2015 Brown University news release (also on EurekAlert), which originated the news item, describes the research in more detail,

When Haneesh Kesari, assistant professor of engineering at Brown, first saw this structure, he wasn’t sure what to make of it. But the pattern of decreasing thickness caught his eye.

“It was not at all clear to me what this pattern was for, but it looked like a figure from a math book,” Kesari said. “It had such mathematical regularity to it that I thought it had to be for something useful and important to the animal.”

The lives of these sponges depend on their ability to stay fixed to the sea floor. They sustain themselves by filtering nutrients out of the water, which they cannot do if they’re being cast about with the flow. So it would make sense, Kesari thought, that natural selection may have molded the creatures’ spicule anchors into models of strength — and the thickness pattern could be a contributing factor.

“If it can’t anchor, it can’t survive,” Kesari said. “So we thought this internal structure must be contributing to these spicules being a better anchor.”

To find out, Kesari worked with graduate student Michael Monn to build a mathematical model of the spicules’ structure. Among the model’s assumptions was that the organic layers between the glass cylinders allowed the cylinders to slide against each other.

“We prepared a mechanical model of this system and asked the question: Of all possible ways the thicknesses of the layers can vary, how should they vary so that the spicule’s anchoring ability is maximized?” Kesari said.

The model predicted that the structure’s load capacity would be greatest when the layers decrease in thickness toward the outside, just as was initially observed in actual spicules. Kesari and Monn then worked with James Weaver and Joanna Aizenberg of Harvard’s Wyss Institute for Biologically Inspired Engineering, who have worked with this sponge species for years. The team carefully compared the layer thicknesses predicted by the mechanics model to the actual layer thicknesses in more than a hundred spicule samples from sponges.

The work showed that the predictions made by the model matched very closely with the observed layer thicknesses in the samples. “It appears that the arrangement and thicknesses of these layers does indeed contribute to the spicules’ strength, which helps make them better anchors,” Kesari said.

The researchers say this is the first time to their knowledge that anyone has evaluated the mechanical advantage of this particular arrangement of layers. It could add to the list of useful engineered structures inspired by nature.

“In the engineered world, you see all kinds of instances where the external geometry of a structure is modified to enhance its specific strength — I-beams are one example,” Monn said. “But you don’t see a huge effort focused toward the internal mechanical design of these structures.”

This study, however, suggests that sponge spicules could provide a blueprint for load-bearing beams made stronger from the inside out.

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

New functional insights into the internal architecture of the laminated anchor spicules of Euplectella aspergillum by Michael A. Monn, James C. Weaver, Tianyang Zhang, Joanna Aizenberg, and Haneesh Kesari. Published online before print April 6, 2015, doi: 10.1073/pnas.1415502112 PNAS April 6, 2015

This paper is behind a paywall.

*’A Venus flower basket sea sponge’ corrected to ‘Venus’ flower basket sea sponge’ on Jan. 5, 2017

De-icing film for radar domes adapted for use on glass

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Interesting to see that graphene is in use for de-icing. From a Sept. 16, 2014 news item  on ScienceDaily,

Rice University scientists who created a deicing film for radar domes have now refined the technology to work as a transparent coating for glass.

The new work by Rice chemist James Tour and his colleagues could keep glass surfaces from windshields to skyscrapers free of ice and fog while retaining their transparency to radio frequencies (RF).

A Sept. 16, 2014 Rice University news release on EurekAlert, which originated the news item, describes the technology and its new application in more detail,

The material is made of graphene nanoribbons, atom-thick strips of carbon created by splitting nanotubes, a process also invented by the Tour lab. Whether sprayed, painted or spin-coated, the ribbons are transparent and conduct both heat and electricity.

Last year the Rice group created films of overlapping nanoribbons and polyurethane paint to melt ice on sensitive military radar domes, which need to be kept clear of ice to keep them at peak performance. The material would replace a bulky and energy-hungry metal oxide framework.

The graphene-infused paint worked well, Tour said, but where it was thickest, it would break down when exposed to high-powered radio signals. “At extremely high RF, the thicker portions were absorbing the signal,” he said. “That caused degradation of the film. Those spots got so hot that they burned up.”

The answer was to make the films more consistent. The new films are between 50 and 200 nanometers thick – a human hair is about 50,000 nanometers thick – and retain their ability to heat when a voltage is applied. The researchers were also able to preserve their transparency. The films are still useful for deicing applications but can be used to coat glass and plastic as well as radar domes and antennas.

In the previous process, the nanoribbons were mixed with polyurethane, but testing showed the graphene nanoribbons themselves formed an active network when applied directly to a surface. They were subsequently coated with a thin layer of polyurethane for protection. Samples were spread onto glass slides that were then iced. When voltage was applied to either side of the slide, the ice melted within minutes even when kept in a minus-20-degree Celsius environment, the researchers reported.

“One can now think of using these films in automobile glass as an invisible deicer, and even in skyscrapers,” Tour said. “Glass skyscrapers could be kept free of fog and ice, but also be transparent to radio frequencies. It’s really frustrating these days to find yourself in a building where your cellphone doesn’t work. This could help alleviate that problem.”

Tour noted future generations of long-range Wi-Fi may also benefit. “It’s going to be important, as Wi-Fi becomes more ubiquitous, especially in cities. Signals can’t get through anything that’s metallic in nature, but these layers are so thin they won’t have any trouble penetrating.”

He said nanoribbon films also open a path toward embedding electronic circuits in glass that are both optically and RF transparent.

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

Functionalized Graphene Nanoribbon Films as a Radiofrequency and Optically Transparent Material by Abdul-Rahman O. Raji, Sydney Salters, Errol L. G. Samuel, Yu Zhu, Vladimir Volman, and James M. Tour. ACS Appl. Mater. Interfaces, Article ASAP DOI: 10.1021/am503478w Publication Date (Web): September 4, 2014
Copyright © 2014 American Chemical Society

This paper is behind a paywall.

De-icing is a matter of some interest in the airlines industry as I noted in my Nov. 19, 2012 posting about de-icing airplane wings.

The glassy side of fractals

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An April 24, 2014 news item on Nanowerk highlights a breakthrough in glass (wordplay intended),

Colorful church windows, beads on a necklace and many of our favorite plastics share something in common — they all belong to a state of matter known as glasses. School children learn the difference between liquids and gases, but centuries of scholarship have failed to produce consensus about how to categorize glass.

Now, combining theory and numerical simulations, researchers have resolved an enduring question in the theory of glasses by showing that their energy landscapes are far rougher than previously believed.

An April 23, 2014 Duke University news release by Erin Weeks (also on EurekAlert), which originated the news item, provides a diagram (am I the only one who thinks these resemble cow udders?) and more infotmation,

Glasses form when their molecules get jammed into fractal "wells," as shown on the right, rather than smooth or slightly rough wells (left). Photo credit: Patrick Charbonneau. Courtesy: Duke University

Glasses form when their molecules get jammed into fractal “wells,” as shown on the right, rather than smooth or slightly rough wells (left). Photo credit: Patrick Charbonneau. Courtesy: Duke University

“There have been beautiful mathematical models, but with sometimes tenuous connection to real, structural glasses. Now we have a model that’s much closer to real glasses,” said Patrick Charbonneau, one of the co-authors and assistant professor of chemistry and physics at Duke University.

…

One thing that sets glasses apart from other phase transitions is a lack of order among their constituent molecules. Their cooled particles become increasingly sluggish until, caged in by their neighbors, the molecules cease to move — but in no predictable arrangement. One way for researchers to visualize this is with an energy landscape, a map of all the possible configurations of the molecules in a system.

Charbonneau [Patrick Charbonneau, one of the co-authors and assistant professor of chemistry and physics at Duke University] said a simple energy landscape of glasses can be imagined as a series of ponds or wells. When the water is high (the temperature is warmer), the particles within float around as they please, crossing from pond to pond without problem. But as you begin to lower the water level (by lowering the temperature or increasing the density), the particles become trapped in one of the small ponds. Eventually, as the pond empties, the molecules become jammed into disordered and rigid configurations.

“Jamming is what happens when you take sand and squeeze it,” Charbonneau said. “First it’s easy to squeeze, and then after a while it gets very hard, and eventually it becomes impossible.”

Like the patterns of a lakebed revealed by drought, researchers have long wondered exactly what “shape” lies at the bottom of glass energy landscapes, where molecules jam. Previous theories have predicted the bottom of the basins might be smooth or a bit rough.

“At the bottom of these lakes or wells, what you find is variation in which particles have a force contact or bond,” Charbonneau said. “So even though you start from a single configuration, as you go to the bottom or compress them, you get different realizations of which pairs of particles are actually in contact.”

Charbonneau and his co-authors based in Paris and Rome showed, using computer simulations and numeric computations, that the glass molecules jam based on a fractal regime of wells within wells.

The new description makes sense of several behaviors seen in glasses, like the property known as avalanching, which describes a random rearrangement of molecules that leads to crystallization.

…

Understanding the structure of glasses is more than an intellectual exercise — materials scientists stand to advance from the knowledge, which could lead to better control of the aging of glasses.

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

Fractal free energy landscapes in structural glasses by Patrick Charbonneau, Jorge Kurchan,     Giorgio Parisi, Pierfrancesco Urbani & Francesco Zamponi. Nature Communications 5, Article number: 3725 doi:10.1038/ncomms4725 Published 24 April 2014

This paper is behind a paywall but there is a free preview available through ReadCube Access.

Glass is a challenge to measure but scientists at Canada’s University of Waterloo have figured out how

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Glass, as many folks know, has a dual nature, being simultaneously both liquid and solid, making truly accurate measurement a bit of a challenge.  A March 3, 2014 news item on Azonano notes that scientists at Canada’s Waterloo University have solved the surface measurement problems with glass,

University of Waterloo physicists have succeeded in measuring how the surfaces of glassy materials flow like a liquid, even when they should be solid.

…

Understanding the mobility of glassy surfaces has implications for the design and manufacture of thin-film coatings and also sets practical limits on how small we can make nanoscale devices and circuitry.

The work is the culmination of a project carried out by a research team led by Professor James Forrest and doctoral student Yu Chai from the University of Waterloo as well as researchers from École Superieure de Physique et de Chimie Industrielles in France and McMaster University [Canada].

A Feb. 28  2014 University of Waterloo news release (also on EurekAlert) by Katharine Tuerke, which originated the news item, describes the research in further detail,

“Common sense would tell you that if a material is solid, it’s solid everywhere. But we’ve shown that a solid isn’t a solid everywhere,” says James Forrest, a professor in Waterloo’s Department of Physics and Astronomy.  “It’s almost solid everywhere –  except a few nanometers at the surface.”

A series of simple and elegant experiments were the solution to a problem that has been plaguing condensed matter physicists for the past 20 years. The experiments revealed that at a certain temperature range, solid glassy materials actually have a very thin liquid-like layer at the surface.

…

Glass is much more than the material in bottles and windows. In fact, any solid without an ordered, crystalline structure is considered a glassy material, so metals, small molecules, and polymers can all be made into glassy materials.

Polymers, the building block of all plastics, are almost always glassy rather than crystalline. These materials undergo a transition between a brittle solid and a molten liquid in a narrow temperature range, which encompasses the so-called glass transition temperature.

In a series of experiments, Forrest and colleagues started with very thin slices of polystyrene stacked to create tiny staircase-like steps about 100-nanometres high – less than 0.001 per cent the thickness of a human hair. They then measured these steps as they became shorter, wider and less defined over time.

The simple 2-dimensional profile of this surface step allowed the physicists to numerically model the changes to the surface’s geometry above and below the glass transition temperature.

Results show that above the transition temperature, polystyrene flows entirely like a liquid; but below this temperature the polymer becomes a solid with a thin liquid-like layer at the surface.

Forrest is also a University Research Chair, a member of the Waterloo Institute for Nanotechnology and an associate faculty member at the Perimeter Institute.

The project team also includes Kari Dalnoki-Veress and J.D. McGraw from McMaster University and Thomas Salez, Michael Benzaquen and Elie Raphael of the École Superieure de Physique et de Chimie Industrielles in Paris.

The researchers have provided a 21 second animation to illustrate their work,

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

A Direct Quantitative Measure of Surface Mobility in a Glassy Polymer by Y. Chai, T. Salez, J. D. McGraw, M. Benzaquen, K. Dalnoki-Veress, E. Raphaël, & J. A. Forrest. Science 28 February 2014: Vol. 343 no. 6174 pp. 994-999 DOI: 10.1126/science.1244845

This paper is behind a paywall.

*University of Waterloo (Canada) and three of its nano startup companies

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All three of these University of Waterloo (UW) startups could be said to feature windows in one fashion or another but it is a bit of a stretch to describe their products as ‘window-oriented’ since these entrepreneurs have big plans.

The first company I’m mentioning is Lumotune, a company whose homepage features NanoShutters and this tagline, “Smarter Glass for a Smarter World”. A Dec. 10, 2013 article by Terry Pender for GuelphMercury.com provides a description of this product which is controlled by a smartphone application,

The product is made of two thin sheets of clear plastic. In between the sheets is the nanotechnology the trio started developing as a school project. The optics of the glass can easily be changed from clear to opaque using a laptop, tablet or smartphone.

The NanoShutters adhere to a window and are connected to a control box with tiny wires. The control box can be plugged into a laptop or controlled wirelessly with tablets and smartphones.

The control box is the most important part of the NanoShutters; the founders have applied for a patent to protect their ownership of it.

“That is basically the core technology,” Esfahani said. “It is futuristic to be able to control what passes through your window with your phone.”

Esfahani, Safaee and Siddiqi [Lumotune founders: Matin Esfahani, Hooman Safaee and Shafi Siddiqi] started all this as a project for their undergrad studies in 2011. They developed the technology, showcased it in March, won a lot of awards, incorporated Lumotune in April, and then collected their degrees from UW.

NanoShutters, the first commercial product to come out of Lumotune, is now in testing with a group of residential, commercial and institutional customers. The founders are using the testing to smooth out kinks and challenges in the technology and develop relationships with customers.

Safaee estimates the market for NanoShutters will be worth about $4 billion a year by 2016.

But the company was founded with much bigger ideas in mind. Instead of using their invention to make windows more or less transparent, they want the product to be used for digital displays that can be put on any surface with no visible technology.

I was not able to find any more details about how nanotechnology enables this window or, more accurately, glass ‘frosting’ experience (perhaps there’s some information in the installation guide mentioned later in this post) but the inventors do offer this video demonstrating their product,

Here’s more from the company’s homepage,

Windows drain energy and reduce privacy. NanoShutters can be fully automated to turn your window opaque or transparent according to the weather and your schedule. They can help lower heating and cooling costs by up to 20%, while always enabling privacy when you need it.

…

If you’re comfortable putting up a poster and setting up a toaster, you can install NanoShutters yourself. It takes less than 30 minutes. See how easy it is.

You can also get installation from a local NanoShutters Certified Professional.

I did click to find out if there’s a NanoShutter professional nearby but it appears there aren’t any entries yet so this may be an opportunity for entrepreneurial types.

The next two University of Waterloo startups are here courtesy of a Dec. 10, 2013 news item on DigitalJournal.com,

Harsh winter conditions may be easier for Canadians to manage with new products invented by two University of Waterloo graduates.

“Frost is a major problem for individuals and businesses daily. Not only is it inconvenient but it has an impact on safety and can even hinder economic activity,” said Abhinay Kondamreddy, a nanotechnology engineering graduate who developed Neverfrost along with three classmates.

…

For contractors who drop salt on parking lots and sidewalks, as well as the municipalities or owners who pay for it, there’s never been a way to measure how much salt is actually dispensed. Smart Scale, an automated salt logging and tracking system designed specifically for the winter maintenance industry is changing that.

The Dec. 10, 2013 University of Waterloo news release, which originated the news item, provides more detail about both Neverfrost and Smart Scale (Note: Links have been removed),

Neverfrost is an environmentally-friendly technology that prevents frost, fog, and ice formation. The innovation is the foundation for a new startup, also called Neverfrost.

By spraying Neverfrost on a windshield at night, drivers can avoid scraping and defrosting it on cold winter mornings, and clear the windshield simply by running the wipers. The Neverfrost technology prevents snow from freezing to the glass as well as fog and frost. Neverfrost expects to begin taking pre-orders for the spray with a Kickstarter campaign in March.Future plans for Neverfrost include incorporating it directly into washer fluids.

Frost and ice create challenges for aircrafts, air conditioning, commercial refrigerators, power lines, and agriculture – creating future opportunities for the Neverfrost technology.

Kondamreddy is one of two entrepreneurs who continue to further their technologies and startups thanks to a $60,000 Scientists and Engineers in Business fellowship. The fellowship is a University of Waterloo program supported by the Federal Economic Development Agency for Southern Ontario for promising entrepreneurs who want to commercialize their innovations and start high-tech businesses.

…

Developed by Raqib Omer, a Waterloo Engineering graduate, Smart Scale uses exclusive hardware wirelessly paired with GPS-enabled smart phones to track the location of a maintenance vehicle and amount of salt dispensed, and logs the information on a cloud-based system in real time. Since the cost of salt is based on size of load, property owners can be assured they’re getting what they paid for, as well as reducing risks that exist in the industry.

“With growing public concern on the environmental effects of salt, rising salt prices, and increasing fear of litigation due to slips and falls, as well as driving conditions, reliable and accurate information on salt application is becoming a necessity for maintenance contractors,” said Omer.

More than 20 winter maintenance contractors in Canada and the U.S., including Urban Meadows Property Maintenance Group in Ayr, Ontario, currently use Smart Scale.

Urban Meadows owner, William Jordan, met Omer in the early testing phase of Smart Scale and the startup phase of Omer’s company, Viaesys. As the first contractor to test Smart Scale, he quickly learned there were times his company was using too much salt.

“The accuracy rate wasn’t there at all,” said Jordan. “We’re now able to accurately monitor salt usage, prevent excessive material use, keep bullet-proof records of our work and job-cost a lot better. The real time tracking of salt has helped us use up to 30 per cent less salt.”

Smart Scale is now installed on all four of his company’s trucks which service 75 properties in Cambridge and Ayr, including parking lots for grocery stores and post offices.

Jordan, who is also chair of the snow and ice committee management sector for the horticultural trade association, Landscape Ontario, says he quickly jumped on board with Omer’s research and would like to see Smart Scale change the way salt is applied across Ontario. With no industry standards for salt application currently in place, Smart Scale could make this possible.

You can find Neverfrost and an opportunity to beta test the product here. I’ve not been able to find a website featuring Smart Scale but here’s Viaesys, a company founded by Raqib Omer, the person who developed the product. I was not able to find additional technical details for either Neverfrost or Smart Scale on either of the company websites.

* ‘Unviersity’ corrected to ‘University’  in posting header on Dec. 13, 2013. I uttered a very loud Drat! when I saw it.

Australians inspired by Lycurgus Cup

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The Lycurgus Cup is one of the great artistic achievements in history and there’s a nanotechnology twist to this art work created in the 4th century CE (or AD). From the Nov. 21, 2013 news item on Nanowerk,

A 1700-year-old Roman glass cup is inspiring University of Adelaide [Australia] researchers in their search for new ways to exploit nanoparticles and their interactions with light.

Researchers in the University’s Institute for Photonics and Advanced Sensing (IPAS) are investigating how to best embed nanoparticles in glass – instilling the glass with the properties of the nanoparticles it contains.

Before going further with this latest work at the University of Adelaide, here’s an excerpt from my Sept. 21, 2010 posting where I burbled on about the best of piece of writing I’ve seen about the Lycurgus Cup (held in the British Museum),

The *History of the Ancient World website (as Nov. 21, 2013 the link has been changed to the Université de Strasbourg,, Matière Condensée et Nanophysique website) recently featured a 2007 article about the Lycurgus Cup by Ian Freestone, Nigel Meeks, Margaret Sax and Catherine Higgitt for the Gold Bulletin, Vol. 40:4 (2007),

The Lycurgus Cup represents one of the outstanding achievements of the ancient glass industry. This late Roman cut glass vessel is extraordinary in several respects, firstly in the method of fabrication and the exceptional workmanship involved and secondly in terms of the unusual optical effects displayed by the glass.

The Lycurgus Cup is one of a class of Roman vessels known as cage cups or diatreta, where the decoration is in openwork which stands proud from the body of the vessel, to which it is linked by shanks or bridges Typically these openwork “cages” comprise a lattice of linked circles, but a small number have figurative designs, although none of these is as elaborate or as well preserved as the Lycurgus Cup. Cage cups are generally dated to the fourth century A.D. and have been found across the Roman Empire, but the number recovered is small, and probably only in the region of 50-100 examples are known. They are among the most technically sophisticated glass objects produced before the modern era.

Here’s what it looks like,

The Lycurgus Cup 1958,1202.1 in reflected light. Scene showing Lycurgus being enmeshed by Ambrosia, now transformed into a vine-shoot. Department of Prehistory and Europe, The British Museum. Height: 16.5 cm (with modern metal mounts), diameter: 13.2 cm. © The Trustees of the British Museum

The Lycurgus Cup 1958,1202.1 in reflected light. Scene showing Lycurgus being enmeshed by Ambrosia, now transformed into a vine-shoot. Department of Prehistory and Europe, The British Museum. Height: 16.5 cm (with modern metal mounts), diameter: 13.2 cm. © The Trustees of the British Museum

And this, too, is the one and only Lycurgus Cup,

The Lycurgus Cup 1958,1202.1 in transmitted light. Scene showing Lycurgus being enmeshed by Ambrosia, now transformed into a vine-shoot. Department of Prehistory and Europe, The British Museum. Height: 16.5 cm (with modern metal mounts), diameter: 13.2 cm. © The Trustees of the British Museum

The Lycurgus Cup 1958,1202.1 in transmitted light. Scene showing Lycurgus being enmeshed by Ambrosia, now transformed into a vine-shoot. Department of Prehistory and Europe, The British Museum. Height: 16.5 cm (with modern metal mounts), diameter: 13.2 cm. © The Trustees of the British Museum

The Nov. 21, 2013 University of Adelaide, news release, which originated the news item, explains why the Lycurgus Cup is of such interest, and why the same cup can be green or red

The Lycurgus Cup, a 4th century cup held by the British Museum in London, is made of glass which changes colour from red to green depending on whether light is shining through the Cup or reflected off it. It gets this property from gold and silver nanoparticles embedded in the glass.

“The Lycurgus Cup is a beautiful artefact which, by accident, makes use of the exciting properties of nanoparticles for decorative effect,” says Associate Professor Ebendorff-Heidepriem. “We want to use the same principles to be able to use nanoparticles for all sorts of exciting advanced technologies.”

Nanoparticles need to be held in some kind of solution. “Glass is a frozen liquid,” says Associate Professor Ebendorff-Heidepriem. “By embedding the nanoparticles in the glass, they are fixed in a matrix which we can exploit.”

Associate Professor Ebendorff-Heidepriem is leading a three-year Australian Research Council Discovery Project to investigate how best to embed nanoparticles; looking at the solubility of different types of nanoparticles in glass and how this changes with temperature and glass type, and how the nanoparticles are controlled and modified.

Practical applications, according to the news release, include,

“Nanoparticles and nanocrystals are the focus of research around the world because of their unique properties that have the potential to bring great advances in a wide range of medical, optical and electronic fields,” says Associate Professor Heike Ebendorff-Heidepriem, Senior Research Fellow in the University’s School of Chemistry and Physics. “A process for successfully incorporating nanoparticles into glass, will open the way for applications like ultra low-energy light sources, more efficient solar cells or advanced sensors that can see inside the living human brain.”

“We will be able to more readily harness these nanoscale properties in practical devices. This gives us a tangible material with nanoparticle properties that we can shape into useful forms for real-world applications. And the unique properties are actually enhanced by embedding in glass.”