Things are heavy right now, man. People are fighting wars, Wall Street is occupied, a large percentage of the workforce can’t find jobs, airport security procedures intensify in complexity by the minute, the rainforest is shrinking as I type … and that’s just the tip of the rapidly melting iceberg. So if you’re already feeling like Atlas with the weight of the world on your shoulders, you’ll be glad to find out that scientists recently invented a material so lightweight it makes styrofoam seem as heavy as a lead ingot.

In fact, “with a density of just 0.9 mg/cm3 the material is around 100 times lighter than Styrofoam and lighter than … ‘multiwalled carbon nanotube (MCNT) aerogel’ – also dubbed ‘frozen smoke’ – with a density of 4 mg/cm3” (Quick). Learn more about aerogels here.

Researchers at UC Irvine, HRL Laboratories and Caltech created an “ultralight metallic microlattice,” which, due to its nanoscale structural configuration vaguely reminiscent of the Eiffel tower, which consists 99.9% of air.  The scientists claim that it is the lightest material on earth.  To make the material, researchers fabricated “a lattice of interconnected hollow tubes with a wall thickness 1,000 times thinner than a human hair” (Netburn). It’s so unbelievably light that the researchers made a version out of nickel, placed it on top of a dandelion and … nothing happened; check it – the stalk didn’t even bend:

Photo: Ultralight metallic microlattice — which is 99.9% air — is so light that it can sit atop dandelion fluff without damaging it. Credit: Dan Little / HRL Laboratories

So how, aside from dandelion decoration, might we use an ultralight metallic microlattice?  The new material demonstrates impressive strength and energy absorption, with the ability to recover from compression exceeding 50% strain.  The small wall thickness-to-diameter ratio of the material allows the individual tubes to remain flexible and absorb energy (Quick). The microlattice demonstrates potential for awesomeness across a wide range of applications. It could be used for catalyst supports, acoustic dampening, as impact protection, vibration dampening, in the aerospace industry, possibly in airplanes to save weight and corresponding jet fuel, bike helmets, or maybe even battery electrodes.

I’d like to know if the manufacturing process is scalable, if it’s toxic in any way, what the cost is to make the material, and if its performance decays over time.  But it’s exciting to think about the possibilities – and to imagine little ultralight metallic microlattice samples floating delicately to earth like so many swan feathers floating on the breeze.

WU XING:

The lightest material on earth has been filed … in earth (and metal).

Cited:

Netburn, Deborah. “Scientists Invent Lightest Material on Earth. What Now?” Los Angeles Times online. 11/17/11. Accessed 11/21/11.  URL.

Quick, Darren. “Newly Developed Metallic ‘Microlattice’ Material is World’s Lightest.” Gizmag.com. 11/17/11. Accessed 11/21/11.  URL.

Special thanks to @BBQSnob for the tip.

Image courtesy todayifoundout.com

A fascinating new metal alloy material under development by researchers at the University of Minnesota, led by Professor Richard James, works similar to a generator, producing electric current in the presence of heat energy.

Ni45Co5Mn40Sn10 is a composite of nickel, cobalt, manganese and tin that is multiferroic (has both magnetism and ferroelectricity, yeilding permanent electric polarization).  The alloy “undergoes a reversible phase transformation, in which one type of solid turns into another type of solid when the temperature changes…. Specifically, the alloy goes from being non-magnetic to highly magnetized. The temperature only needs to be raised a small amount for this to happen” (Boyle).  So when you heat this stuff up and place it near a permanent magnet (perhaps a rare-earth magnet) the alloy’s magnetic force increases with all the dramatic intensity of Joan Crawford, producing a current in a nearby coil.

Image courtesy popsci.com

A process called hysteresis, which makes me imagine sixteen distraught women in togas running down the street screaming, crying, and tearing their hair out, causes a small fraction of the heat energy to be lost. Despite all the hysteresis, researchers believe the alloy could be used to convert waste heat energy into large amounts of electricity. Cha ching!

Auto manufacturers are currently working on heat transfer devices that can convert hot car exhaust into useable electricity.  General Motors has been looking at alloys called “skutterudites” made from cobalt-arsenide materials “doped with rare earths” (Boyle). The material could also be used to make heat-capture devices that could be placed near the rare earth magnets in hybrid car batteries, or used for power plants or even ocean thermal energy generators, according to the researchers.

WU XING:

I have filed this post under Metals due to the prevalence of the alloys and the metals and whatnot.

Cited:

Boyle, Rebecca. “New Alloy can Convert Heat Directly into Electricity.” Popsci. 06/22/11. Accessed 06/24/11. URL.

Image courtesy ursulinesmsj.org

But since there’s no cake, I’m going to write about a new metal panel product coated with, you guessed it: titanium dioxide.  Bonding this chemical to various materials is a growing trend in green building (read about ceramic tiles coated with TiO₂ here) because it’s thought to break down organic matter, SOx (sulphur oxides), and NOx (nitrogen oxides) – the primary component of smog.

Image courtesy ecoclean.com

Alcoa Architectural products has developed a process of applying a titanium dioxide coating called “EcoClean” (the green product naming equivalent of SuperAwesomeAmazingPerfectSauce) to the pre-painted aluminum surface of their Reynobond aluminum panels. As a consequence of the TiO₂ coating, the panels are self-cleaning and break down everything from bird droppings to harmful pollutants.

Image courtesy ecoclean.com

The panels actively remove pollutants from the air in the presence of water and sunlight.  Free radicals generated by the titanium dioxide oxidize the NOx molecules and render them harmless.  Rain washes all said harmless dirt and crud right off the panels, meaning lower maintenance costs for owners and a cleaner image for the building over time (architect is happy! yay!).

Image courtesy ecoclean.com

According to the product literature, installing TiO₂ coated panels “on your building can have approximately enough cleansing power to offset the smog created by the pollution output of four cars every day, which is the approximate air cleansing power of 80 trees every day” (Source: Ecoclean.com).

WU XING:

I am filing this under metal because of the aluminum panels and water because it’s a necessary ingredient for the process to work.

Similar issues arise in the making of structural materials such as metals and alloys. The materials properties are set once and for all during production. This forces engineers to make compromises in the selection of the mechanical properties of a material. Greater strength is inevitably accompanied by increased brittleness and a reduction of the damage tolerance.”

Image courtesy Technical University of Hamburg and the Helmholtz Center Geesthacht

Jörg Weißmüller, a materials scientist at both the Technical University of Hamburg and the Helmholtz Center Geesthacht, and his team wondered if you could switch METALS back and forth between different degrees of firmness.  They placed precious metals (gold, platinum, what have you) in an acid bath. The acid corroded the metals, creating teensy tiny holes and channels all through the material, which they subsequently filled with a conductive liquid (dilute acid or saline solution).

Image courtesy Technical University of Hamburg and the Helmholtz Center Geesthacht

Ions dissolved in the conductive liquid influence the surface atoms of the metal, withdrawing or adding electrons to the metal’s surface atoms depending on the charge of the liquid.  Controlled changes in the atomic configuration can double the strength of the metallic materials, or make it weaker and more damage tolerant (Dillow).  The union of metal and water allows the researchers to alter the properties of the material at the touch of a button – an amazing breakthrough!

These “research findings could, for example, make future intelligent materials with the ability of self healing, smoothing out flaws autonomously….  Specific applications are still a matter for the future. However, researchers are already thinking ahead. In principle, the material can create electric signals spontaneously and selectively, so as to strengthen the matter in regions of local stress concentration. Damage, for instance in the form of cracks, could thereby be prevented or even healed. This has brought scientists a great step closer to their objective of ‘intelligent’ high performance materials.” (Source: Eurekalert). Not to mention it would make for a pretty sweet Iron Man suit… I’m just saying.

WU XING:
Filed under Metal and Water.

Cited:

Dillow, Clay. “New Nanometal Changes from Hard to Soft at the Flip of a Switch.” Popsci.com. 06/08/11. Accessed 06/09/11. URL.

“Hard or Soft: at the Touch of a Button.” Public release date: 6-Jun-2011. via Eurekalurt URL.

NASA certainly thinks so, and to that end they have awarded four research groups a cool $16.5 million* to make airplanes run more efficiently, quietly, and less dangerously than ever before. One of the groups is a Cessna and GE team, and they are developing a “Smoothing, Thermal, Absorbing, Reflective, Conductive, Cosmetic” skin for planes.  The self-healing skin, which has been dubbed STAR-C2 for short, protects metal tubes with wings against a host of horrible threats like impact damage, lightning strikes, electromagnetic interference (EMI), temperature extremes, and it insulates the cabin from noise (Dillow). If you’re like me, you wouldn’t be surprised to learn that STAR-C2 also makes a delightful coq au vin and regularly vacuums the drapes without anybody asking. (Okay, I made up that last part, but that would be nice, wouldn’t it?)

Image courtesy http://ivanovict89.wordpress.com

The research team is working on technology that would make its way into airplanes three generations from now (equivalent to about 25-30 years).  It will be worth the weight: “in the final report on its original N+3 study, the GE/Cessna team calculated that the new outer skin made from conductive film and energy-absorbing foam would more than halve the weight of the various measures that now must be taken to protect composite materials from environmental hazards” (Warwick). The material would be self-healing if punctured or torn, but it would also be designed to show damage so that any problems would become apparent to trained inspectors on the ground.

Image courtesy popsci.com

I don’t think the researchers should stop at airplanes. I want to clad entire buildings in this stuff! I don’t see a single benefit that wouldn’t make a building function better, and we have nearly three decades to figure out how to bring the cost of manufacturing it down to something reasonable. I’m excited!

WU XING:

I am filing STAR-C2 under metal and wood, because it enjoys properties of both elements.

*This is a reference to the following passage in Great Expectations by Charles Dickens, which for some reason stuck in my head when I read it in 9th grade:

“I never discovered from whom Joe derived the conventional temperature of the four thousand pounds; but it appeared to make the sum of money more to him, and he had a manifest relish in insisting on its being cool.”

Cited:

Dillow, Clay. “NASA Wants Airliners Wrapped in Self-Healing, Lightning-proof, Interference-repelling ‘Magic Skin'” Popsci.com. 4/7/11. Accessed 4/7/11. URL.

Warwick, Graham. “Cessna to Study Magic Skin for NASA.” Aviationweek.com. 4/5/11. Accessed 4/7/11. URL.

Until this week I thought that Charlie Sheen was your ordinary aging Hollywood actor. Really, if I thought about him at all, I assumed he was working on a TV show, staying tan/undergoing the occasional face lift, failing at some marriages, and I believed that human blood and maybe some high-quality cocaine were flowing through his veins. But now I have a completely different perspective.  Now I know that Charlie Sheen has tiger blood and adonis DNA, and that he is a total freakin’ rock star from Mars.  

As if that news weren’t enough, I also learned this week that a team of scientists at Yale University have discovered that bulk metallic glasses (BMGs) – which are metal alloys whose atoms are randomly arranged (in constrast with the ordered, crystalline structures found in typical metals) – can be blow molded like plastics into complex shapes that ordinary metal can’t achieve without losing any strength or durability (Physorg.com). BMGs are biwinning. They win here, they win there. I can’t process this with my normal brain!

These alloys, made up of zirconium, nickel, titanium, and copper, which look like metal but can be molded as inexpensively and as quickly as plastic have allowed researchers to fabricate a number of complex shapes, including “seamless metallic bottles, watch cases, miniature resonators and biomedical implants-that can be molded in less than a minute and are twice as strong as typical steel” (Physorg.com). Like Charlie, they only have one speed, they have one gear: GO.

Image courtesy physorg.com

In fluid or a vacuum at low temperatures and pressures, the bulk metallic glass softens and flows like plastic without crystalizing. This allowed the reaserchers to shape the BMGs with unprecedented ease, versatility and precision.  Three separate steps in traditional metal processing (shaping, joining, and finishing) were combined into one step (Physorg.com). BOOM! That’s the whole movie. That’s life.

If BMGs are as easy to recycle as traditional metals and less toxic than plastics, then they will revolutionize the way we live. Radical.

WU XING:

Filed under metal. (For the win, bro).

Cited:

“Stronger than Steel, Novel Metals are Moldable as Plastic” Physorg.com 03/01/11. Accessed 03/03/11. URL.

I ordered a sample of super elastic plastic from Inventables, and when it came in I decided that it would be a lot easier to physically demonstrate how stretchy it is, rather than merely describing the elastic qualities of the material. Also the plastic came a lovely shade of pink (which may or may not have influenced my decision to order it in the first place) and I thought you might like to see the pinkness of it. All this is to say that I just made my first Materials in Motion video post, and I hope you will find it entertaining and educational.

A short film about stretchy pink plastic by ARCHITERIALS.com

WU XING:

I filed super elastic plastic under Metal and Wood, because the characteristics of plasticity flexibility, ductility, etc, are often attributed to these elements.

I bring this up because I’m working on a project right now where a glowing ceiling is the goal. It’s a small, house-sized commercial structure whose organization responds to a grid that extends across an enormous site. Neighboring buildings consist of utterly huge cultural institutions, so this grid, which is expressed by cuts in the concrete paving and in the organization of landscape elements, is substantially out of scale with the tiny little building. That acknowledged, the grid is setting the size for the translucent acrylic ceiling panels that we’re planning to install inside the structure so light can shine through and the ceiling will glow. I can’t include a picture of the project, but the image below should get the general idea across:

Image courtesy http://www.extenzo.com/

I don’t know if you’ve worked with 1/2″ translucent acrylic panels lately, but let me tell you: they are all kinds of heavy. As originally designed, each of our panels would have weighed 300 pounds, causing a deflection of approximately 0.7″ (which means that our glowing ceiling would take on an appearance that can only be described as pillowed, undeniably and distastefully similar to deluxe toilet paper. One highly intriguing solution (which at the time of this writing is not being pursued, meaning I get to write about what I’ve learned instead of drawing it into our construction documents) would be to install a light weight, translucent, stretch fabric ceiling – rather than cutting the panels down and jumping through proverbial hoops to support their weight (…er – not that that is happening).

Image courtesy Newmat USA

Stretch fabric ceiling systems consist of a ceiling membrane, rails to attach the membrane to the walls, rings or grommets to allow light fixtures and other miscellaneous objects to penetrate the membrane, and subframing, which allows the membrane to change direction, slope, etc. The ceiling membranes can be obtained in many different finishes from various manufacturers, including lacquer, matte, mesh, perforated, and of course, translucent.  Two companies I’ve been researching lately are Newmat USA and Extenzo. Looking at photos of their installations made me wonder if I haven’t seen stretch ceilings installed without realizing they were there.

One of the major problems with glowing ceilings is the fact that the glow doesn’t last forever. Eventually lamps burn out, no matter what, and you have to change them. Using big heavy ceiling panels means that when this happens, a maintenance person has to find a friend or two, grab a ladder, and start shoving ceiling panels around. If the panels are delicate, they will break. If they are heavy, they will be dropped. A stretch ceiling is light weight and can easily detach from its supporting rails to allow for maintenance, and I’d imagine that replacing a damaged membrane wouldn’t be too difficult.

Image courtesy http://www.extenzo.com/

The other interesting aspect of stretch fabric systems is that they allow the ceiling surface to take on wild deformations that simply aren’t possible with other systems due to how much it would cost or the complexity of fabrication. A project for the customs house in Sydney, Australia by LAVA (Laboratory for Visionary Architecture) is an example of an installation of the product that takes advantage of its properties:

Image courtesy dezeen.com

Has anyone installed one of these systems? Let me know how it went!

WU XING: I’m filing stretch fabric ceilings under metal and wood, because they’re flexible and involve fastening.

Cited:

“Green Void by LAVA.” Dezeen. 12/16/08. Accessed 1/31/11. URL.

Image courtesy http://iopscience.iop.org

I’d long thought invisibility was reserved for fictional characters like Harry Potter, but it turns out researchers are actively trying to develop materials that create the effect.  So-called “metamaterials allow researchers to manipulate electromagnetic waves beyond the boundaries of what physics allows in natural materials. As well as promising better solar cells and high-resolution microscope lenses, metamaterials have also been used to create so-called invisibility cloaks, in which electromagnetic waves are bent around an object as if it simply weren’t there” (Cass).  Metamaterials must be constructed out of elements smaller than the wavelength of the electromagnetic radiation being manipulated, which means that “invisibility cloaks (and most metamaterial devices in general) only work with wavelengths longer than those found in visible light, such as radio and microwave frequencies. Metamaterials designed to work with optical wavelengths are built on rigid and fragile substrates, and as a result they’ve been confined to the lab” (Cass). Not too long ago, researchers at the University of St. Andrews created sheets of a flexible metamaterial that can manipulate visible light, taking a big step towards bringing metamaterials out of the lab and onto the market.

The new metamaterial is called “Metaflex” for obvious reasons, and it’s not exactly a piece of cake to manufacture.  First, researchers deposit a sacrificial layer atop a rigid substrate, to prevent subsequent layers from binding to it.  Then, a sheet of flexible, transparent plastic gets laid down and “a lithographic process, similar to that used to make silicon chips, creates a lattice of gold bars, each 100 to 200 nanometers long and 40 nanometers thick, on top of the polymer. (These bars act as ‘nanoantennas’ that interact with incoming electromagnetic waves.) The Metaflex material is then bathed in a chemical that releases the polymer from the layer below and from the rigid substrate” (Cass).  Variations in length and spacing of nanoantennas let Metaflex interact with different wavelengths of light.

Image courtesy http://iopscience.iop.org

The largest sheets researchers have produced so far are smaller than a postage stamp at five by eight millimeters, and they are only four micrometers thick.  Those samples may seem small when your goal is to cloak an entire person, but Metaflex is by far the largest sample of an optical metamaterial ever made.  Researchers believe that Metaflex can be scaled up for industrial production because it is flexible.  Being able to shape Metaflex into cylinders or spherical sections would allow for the creation of “curved super lenses that could manify objects so small that they currently can’t be seen with optical lenses due to diffraction effects” (Cass). ”  Metaflex can be fabricated flat and bent into shape.

Image courtesy pakrockerx.com

I was reminded of the story of King Midas when I heard about a new materials development by researchers in Taiwan led by Yen Hsun Su and colleagues at Academia Sinica in Taipei and the National Cheng Kung University in Tainan.  The scientists are working to find a way to increase the efficiency of LED lights; to that end they’ve synthesized gold nanoparticles and implanted them into the leaves of the Bacopa caroliniana plant, “a perennial aquatic or semi-aquatic creeping herb commonly used as an aquarium plant” (Edwards) in order to induce bioluminescence. 

Image courtesy www.oregonaquatics.com

Apparently “the green pigment in leaves, chlorophyll, is bioluminescent when exposed to high wavelength (400 nanometers (nm)) ultra violet excitation, but the wavelength is much shorter for the photoluminescence of gold nanoparticles, and they emit light at 400 nm” (Edwards).  The team developed sea-urchin shaped gold nanoparticles, (dubbed nano-sea-urchins or NSUs), and were able to excite the chlorophyll in the Bacopa leaves to emit red light.  Theoretically, the light produced by the leaves would in turn cause their chloroplasts to conduct photosynthesis, meaning that no additional energy source would be needed to power the process.  In fact, the leaves would actually work overtime, absorbing CO₂ at night when they would otherwise be … not doing that (Quick).  It might be possible to develop street trees for cities that bioluminesce to light roadways.

Image courtesy www.inhabitat.com

Nano Sea Urchin image courtesy www.conf.ncku.edu.tw

According to Assistant Professor Shih-Hui Chang, “‘light emitting diode (LED) has replaced traditional light source in many display panels and street lights on the road. A lot of light emitting diode, especially white light emitting diode, uses phosphor powder to stimulate light of different wavelengths. However, phosphor powder is highly toxic and its price is expensive. As a result, Dr. Yen-Hsun Wu had the idea to discover a method which is less toxic to replace phosphor powder which can harm human bodies and cause environmental pollution. This is a major motivation for him to engage in the research at the first place'” (Quick).

Would I like to walk along a street under bioluminescent trees that are offsetting my carbon footprint while lighting my way?  Yes.  Do I think that there might be some unintended consequences relating to the implantation of gold nanoparticles into the leaves of plants, a la the story of king Midas?  Absolutely.  What do you think?

WU XING:

I am filing gold nanoparticles under metal and fire. 

Cited:

Edwards, Lin.  “Gold Nanoparticles that Make Leaves Glow in the Dark.” Physorg.com 11/11/10.  Accessed 11/12/10.  URL.

Quick, Darren. “Gold Nanoparticles turn Trees into Street Lights.” Gizmag.com 11/11/10.  Accessed 11/12/10.  URL.