Showing posts with label materials. Show all posts
Showing posts with label materials. Show all posts

2012-10-22

Nano-Material with Color and Texture of Butterfly Wings

Penn Researchers Find New Way to Mimic the Color and Texture of Butterfly Wings | Penn News


PHILADELPHIA — The colors of a butterfly’s wings are unusually bright and beautiful and are the result of an unusual trait; the way they reflect light is fundamentally different from how color works most of the time.

A team of researchers at the University of Pennsylvania has found a way to generate this kind of “structural color” that has the added benefit of another trait of butterfly wings: super-hydrophobicity, or the ability to strongly repel water.

The research was led by Shu Yang, associate professor in the Department of Materials Science and Engineering at Penn’s School of Engineering and Applied Science, and included other members of her group: Jie Li, Guanquan Liang and Xuelian Zhu.


Butterfly wings biomimicry for dirt free coated surfaces | RobAid


[...] the team exploited microphase separation of crosslinked polymer chains from nonsolvents to generate nanoroughness (≤120 nm) on holographically patterned diamond photonic crystals.

The process of formation of these nanoroughened patterns consists out of spin-coating, pre-exposure bake, exposure, post-exposure bake (PEB), development, solvent rinsing and critical-point drying (CPD). The pattern is etched with the use of a laser which etches a 3D cross-linked pattern in a kind of material called photoresist. A solvent then washes away all the photoresist untouched by the laser, creating the 3D structure that affects light to create the color effects.

SHU YANG GROUP :: RESEARCH

Bio-organisms often exhibit an exquisite array of hierarchical organization with multiscale structures as exemplified by the iridescence in blue Morpho rhetenor butterflies, the waveguiding properties in diatom exoskeletons, the self-cleaning ability of lotus leaves, and the dry adhesion of Gecko foot hairs. These examples provide inspiration for the development of new functional hybrid materials. To mimic hierarchical organization in Nature, one of the emerging strategies is the convergence of top-down microfabrication and bottom-up nanoassembly.




Interview With Professor Shu Yang Of The University of Pennsylvania - Science News - redOrbit

[...]

RO:
Can you give us an idea of what this material would actually look like when applied to a large surface like, say, an office building or a house? Would it really have that same intense, shimmering quality that we associate with peacock feathers and butterfly wings?
Yang: Yes. Since the structural color is a reflective color that is dependent on the structure, it does not suffer photobleaching like pigmentation. As long as the structure maintains its integrity, we will always see the intense shiny color from these materials. However, to fabricate the 3D photonic structures reported in our paper, we used a state-of-art non-conventional 3D lithography technique. So it is not intended for low-cost, large area fabrication. We believe that the concept we demonstrated here is applicable to other fabrication methods.
RO: Aside from its potential use in beautifying the outsides of buildings, have you imagined any other potential uses for such this material, or is that something you plan on leaving to the marketing experts?
Yang: It could be used as a traffic sign, which needs to be shiny and clean in the rainy or snowy days. It could be used as a bulletin board on the highway or on the building. It could be used as a fancy, protective cover of the iPhone or iPad. It could also be used as camouflage or something that could be worn by the soldiers, for example, as blast injury dosimeters.
We are currently looking into new methods that will allow us to mass-produce these materials for potential commercialization. Of course, we welcome any suggestion from experts about market needs.



2012-01-04

Quasicrystals from Outer Space

Bizarre Crystal Hitched Ride on Meteorite | Chondrites & Meteorite Collisions | Space Rocks & Early Solar System | LiveScience

A rock sample containing quasicrystals unearthed in the Koryak Mountains in Russia.
CREDIT: Paul Steinhardt, Princeton University



A rock fragment containing a previously unidentified natural quasicrystal may be the remnant of a  meteorite that originated in the early solar system more than 4.5 billion years ago before Earth even existed.

Until now, researchers had assumed such quasicrystals, whose atoms are arranged in a quasi-regular pattern rather than the regular arrangement of atoms inside a crystal, were not feasible in nature. In fact, until now the only known quasicrystals were synthetic, formed in a laboratory under carefully controlled conditions. (This year's Nobel Prize in chemistry honored Dan Shechtman for his 1982 discovery of quasicrystals, which at the time were thought to break the laws of nature.)

The quasicrystal from outer space : Nature News & Comment

The only known natural example of the material that won last year's Nobel Prize in Chemistry comes from an ancient meteorite.
Alien origins

In the latest study, Bindi joined with Steinhardt and other US scientists to analyse the rock. The ratios of isotopes of oxygen in silicate and oxide minerals around the quasicrystal grain are typical of minerals found in meteorites called carbonaceous chondrites, the team reports1. This indicates that the rock is of extraterrestrial origin and very old: virtually all chondrites formed at the birth of the Solar System. It is likely, but not certain, that the quasicrystal grain within the meteorite is of roughly the same age. It was found entwined with a silica mineral that forms only at high pressures and temperatures — such as might be created by a collision with the chondrite body.

What are Quasicrystals, and What Makes Them Nobel-Worthy? | The Rundown News Blog | PBS NewsHour | PBS


The 2011 Nobel Prize in chemistry was awarded on Wednesday to an Israeli scientist named Dan Shechtman who discovered a type of crystal so strange and unusual that it upset the prevailing views on the atomic structure of matter, leading to a paradigm shift in chemistry.

But why? What's so special about quasicrystals?

[...]

Pat Theil, a senior scientist at the U.S. Energy Department's Ames Laboratory and a professor of materials science at Iowa State University, uses the analogy of tiling a bathroom floor. Only tiles of certain shapes fit together snugly without creating unsightly holes.

"If you want to cover your bathroom floor, your tiles can be rectangles or triangles or squares or hexagons," Thiel said. "Any other simple shape won't work, because it will leave a gap. In a quasicrystal, imagine atoms are at the points of the objects you're using. What Danny discovered is that pentagonal symmetry works."


Introduction to Quasicrystals


1. What Are Quasicrystals ? 
2. The Concept of Higher Dimensional Space 
3. What Do We Need Tilings For ? 
4. Types of Quasicrystals 
5. Diffraction pattern symmetries
6. Systems with Quasicrystals 
7. Experimental Techniques 
8. Structure Solution Techniques 
9. Morphology 
10. IMS versus QC 


2011-12-03

A New Coating Promises 'Self-cleaning' Glasses


'Self-cleaning' surfaces - that repel both oil and water, so are 'immune' to dirt - are very rare.

But a chemist, Doris Vollmer, appears to have stumbled on a new, budged approach by accident - holding slides over Christmas candles to coat them in soot.

The results - after treatment - were both oil and water-repellent. It's a 'eureka' moment that could lead to 'self-cleaning' glass that could be used in glasses, or even skyscraper windows.
The 'self-cleaning' glass was created after experiments where a researcher blackened slides with soot, then chemically treated the soot to be transparent


A New Coating Promises the End of Smudges - Technology Review

First they held the glass slide over a heart-shaped candle (though any candle will do). This led to the deposition of soot on the slide—spheres of soot that were 30 to 40 nanometers in diameter, stacked loosely and producing the right kind of surface texture: about 80 percent empty and 20 percent spheres.

To protect the soot from washing away, they coated it with a silica shell 25 nanometers thick; to get rid of the black color of the soot, they baked the slide at 600 ºC, making it transparent. Afterward, they sprayed various oils—peanut oil and solvents—and took micrographs of these liquid droplets bouncing up and down like ping-pong balls. 

The coating sticks to aluminum, steel, and copper, too. And because it has both oil- and water-repelling qualities, the material is said to be "superamphiphobic."


'It is difficult to say whether this particular work will yield practical applications, but in principle there are many areas where such non-sticky self-cleaning surfaces are needed,' says Michael Nosonovsky, who works at the University of Wisconsin-Milwaukee in the US on omniphobic surfaces. Examples include optical devices and the windows of skyscrapers.

But Vollmer doesn't expect a conveyer belt full of candles to be used to make self-cleaning surfaces any time soon. Instead, she says, she thinks the method is a useful way to investigate how to make omniphobic surfaces. 'Now we're trying to improve it further and get particles that are larger, with better mechanical stability,' she adds 'but still keeping the idea the particles are spherical.'


2009-11-29

Superhydrophobic Materials

clipped from en.wikipedia.org
Superhydrophobe

Superhydrophobic surfaces such as the leaves of the lotus plant have surfaces that are highly hydrophobic, i.e., extremely difficult to wet. The contact angles of a water droplet exceeds 150° and the roll-off angle is less than 10°.[1] This is referred to as the Lotus effect.

The Physical Basis

To understand the physics behind the Lotus-Effect, one has to take a look the
forces that act upon a drop of liquid on a surface.


A droplet on a hydrophilic rough surface seems to sink into the gaps


A droplet on a rough hydrophobic surface sitting on the spikes

Self-Cleaning Properties
clipped from www.ornl.gov

 superhydrophobic materials
Left to right: Water on a lotus leaf; Surface microstructure of the lotus leaf; ORNL "Nano-
Cones" on glass.

clipped from www.youtube.com

Super hydrophobic substances

clipped from video.google.com
Axisymmetric droplet impinging on a hydrophobic surface
clipped from www.youtube.com

Hydration Shell Dynamics of a Hydrophobic Particle

clipped from medtechinsider.com
Some insect wings, for example, are superhydrophobic, which is the combined result of their chemistry and the detailed nanoscale structures on their surface.
IC_Gomphidae_wing
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Sources:
  1. Superhydrophobe - Wikipedia, the free encyclopedia
  2. The Lotus Effect
  3. Advanced Materials: Superhydrophobic Materials
  4. YouTube - Super hydrophobic substances
  5. Axisymmetric droplet impinging on a hydrophobic surface
  6. YouTube - Hydration Shell Dynamics of a Hydrophobic Particle
  7. medtechinsider » Blog Archive » Self-Cleaning Silicone Gel Could Open New Possibilities for Medical Diagnostics
Related:
  1. Science Centric | News | Self-cleaning silicone gel insect wings
  2. Super Water Repellent, Superhydrophobic, Material from ORNL Easy to Fabricate and Uses Inexpensive Base Materials
  3. New Super-Hydrophobic Material Could Revolutionize the Water Repellent Market - Associated Content - associatedcontent.com

2009-05-30

Aerogel

clipped from www.youtube.com
It looks like frozen smoke. And it's the lightest solid material on the planet. Aerogel insulates space suits, makes tennis rackets stronger and could be used one day to clean up oil spills. Lawrence Livermore National Laboratory scientist Alex Gash shows us some remarkable properties of this truly unique substance.
clipped from www.wired.com

A Solid That's Light as Air

Aerogel is the lightest solid known to science. It's also one of the most insulating materials on Earth, the most porous, and it's nearly transparent. Those last two properties made it an ideal choice for catching flecks of comet and interstellar dust on the recently-returned Stardust mission launched by NASA and JPL.

Stardust Banner
tech_comet_dust.gif
trk-s.jpg
Aerogel & Peter Tsou, JPL Scientist
http://stardust.jpl.nasa.gov/highres/p48567a.jpg
Flower On Aerogel Over A Flame
http://stardust.jpl.nasa.gov/highres/flower.jpg
Matches On Aerogel Over A Flame
http://stardust.jpl.nasa.gov/images/gallery/aerogelmatches.jpg
Aerogel Supporting A Brick
http://stardust.jpl.nasa.gov/images/gallery/aerogelbrick.jpg
Aerogel In Hand
http://stardust.jpl.nasa.gov/images/gallery/aerogelhand.jpg

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clipped from www.aerogel.org

How is Aerogel Made?

The Start of an Aerogel: A Gel

Aerogel is the solid framework of a gel isolated from its liquid component, prepared in such a way as to preserve the framework’s pore structure (or at least most of it). In other words, aerogel is what would be left over if you could remove the liquid from a gel without it shrinking. This is most effectively done through a special technique called supercritical drying

Aerogelification




clipped from en.wikipedia.org
Types
Silica aerogels
Carbon aerogels
Alumina aerogels
Other aerogels

SEAgel is a material similar to organic aerogel, made of agar.

clipped from www.youtube.com

SEAgel Aerogel lighter than air solid. Not a UFO


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Sources:
  1. YouTube - QUEST Lab: Aerogel - KQED QUEST
  2. A Solid That's Light as Air
  3. Stardust - NASA's Comet Sample Return Mission
  4. Stardust | JPL | NASA
  5. Stardust | JPL | NASA
  6. Aerogel - Wikipedia, the free encyclopedia
  7. YouTube - SEAgel Aerogel lighter than air solid. Not a UFO
Related:
  1. Aerogel: See-Through, Strong as Steel & Ligher than Air | dornob
  2. Berkeley Lab News Center Feature Story: X-Ray Diffraction Looks Inside Aerogels in 3-D
  3. Aerogel Research at LBL
  4. Scientists hail ‘frozen smoke’ as material that will change world - Times Online
  5. Nanogel Aerogel - Cabot Corporation
  6. Aerogels, Aerogel Material, Nanofoams - MarkeTech International

2009-04-28

Super-Strong Metallic Spider Silk

Clipped from: Scientists make super-strong metallic spider silk | Reuters

Reuters UK

Scientists make super-strong metallic spider silk




LONDON (Reuters) - Spider silk is already tougher and lighter than steel, and now scientists have made it three times stronger by adding small amounts of metal.

The technique may be useful for manufacturing super-tough textiles and high-tech medical materials, including artificial bones and tendons.

"It could make very strong thread for surgical operations," researcher Seung-Mo Lee of the Max Planck Institute of Microstructure Physics in Halle, Germany, said in a telephone interview.


Clipped from: German Scientists Spin Stretchier and Stronger Spider Silk

AZoNano - The A to Z of Nanotechnology

Many insects and other creatures incorporate small amounts of metals such as zinc, manganese, calcium or copper into body parts like jaws, claws and stingers to make them stiffer and harder. The scientists drew on a technique called 'atomic layer deposition' (ALD) to get zinc, titanium and aluminium ions into the spider silk.

Normally ALD just leaves a layer of metal oxides on the surface of the treated fibre; treating spider silk in this way therefore had little impact on its strength. However, by adapting the technique slightly, the researchers were able to get the metal ions to infiltrate the spider silk and become part of the thread.


Clipped from: Max Planck Society - Press Release



Power thrust for spider silk

A team of scientists from Halle has succeeded in making spider silk significantly more break-resistant and ductile through the addition of metals




Fig.: Endurance test for spider silk: in many ways, spider silk - here the picture of a garden cross spider in its web- is stronger than a metal wire of the same thickness. After researchers at the Max Planck Institute for Microstructure Physics infiltrated spider silk with metal ions, a double-strand of silk can support the weight of a cube of 27.5 grams, three times more than an untreated strand.


Despite its dramatically improved properties, metal-infiltrated spider silk is unlikely to be used to reinforce either fenders or aircraft wings in the future. "It would probably be more or less impossible to obtain large volumes of natural spider silk," says Knez. The insects are very difficult to keep and are not particularly productive when it comes to spinning their silk. Nonetheless, Knez is convinced of the practical use of this power thrust for materials: "We are pretty certain that we will also be able to improve the properties of synthetic materials that imitate natural ones using our process."


Clipped from: Greatly Increased Toughness of Infiltrated Spider Silk -- Lee et al. 324 (5926): 488 -- Science

Science Logo

Reports

Greatly Increased Toughness of Infiltrated Spider Silk

Seung-Mo Lee,1,* Eckhard Pippel,1 Ulrich Gösele,1 Christian Dresbach,2 Yong Qin,1 C. Vinod Chandran,3 Thomas Bräuniger,3 Gerd Hause,4 Mato Knez1,*


Sources:
  1. Scientists make super-strong metallic spider silk | Reuters
  2. German Scientists Spin Stretchier and Stronger Spider Silk
  3. Max Planck Society - Press Release
  4. Greatly Increased Toughness of Infiltrated Spider Silk -- Lee et al. 324 (5926): 488 -- Science

Related:
  1. Scientists mix in metal to make super-strength spider silk - Ars Technica
  2. Power thrust for spider silk
  3. Metal Injections Make A Spider Silk that Spiderman Would Envy | 80beats | Discover Magazine
  4. Technology Review: Blogs: TR Editors' blog: Silk That's Tougher Than Spidey's