NANOMATERIALS

May 13, 2016


In recent months there has been considerable information regarding nanomaterials and how those materials are providing significant breakthroughs in R&D.  Let’s first define a nanomaterial.

DEFINITION:

“Nanomaterials describe, in principle, materials of which a single unit is sized (in at least one dimension) between 1 and 1000 nanometres (10−9 meter) but is usually 1—100 nm (the usual definition of nanoscale).”

Obviously microscopic in nature but extremely effective when applied properly to a process.  Further descriptions are as follows:

Nanomaterials must include the average particle size, allowing for aggregation or clumping of the individual particles and a description of the particle number size distribution (range from the smallest to the largest particle present in the preparation).

Detailed assessments may include the following:

  1. Physical properties:
  • Size, shape, specific surface area, and ratio of width and height
  • Whether they stick together
  • Number size distribution
  • How smooth or bumpy their surface is
  • Structure, including crystal structure and any crystal defects
  • How well they dissolve
  1. Chemical properties:
  • Molecular structure
  • Composition, including purity, and known impurities or additives
  • Whether it is held in a solid, liquid or gas
  • Surface chemistry
  • Attraction to water molecules or oils and fats

A number of techniques for tracking nanoparticles exist with an ever-increasing number under development. Realistic ways of preparing nanomaterials for test of their possible effects on biological systems are also being developed.

There are nanoparticles such as volcanic ash, soot from forest fires naturally occurring or the incidental byproducts of combustion processes (e.g., welding, diesel engines).  These are usually physically and chemically heterogeneous and often termed ultrafine particles. Engineered nanoparticles are intentionally produced and designed with very specific properties relative to shape, size, surface properties and chemistry. These properties are reflected in aerosols, colloids, or powders. Often, the behavior of nanomaterials may depend more on surface area than particle composition itself. Relative-surface area is one of the principal factors that enhance its reactivity, strength and electrical properties.

Engineered nanoparticles may be bought from commercial vendors or generated via experimental procedures by researchers in the laboratory (e.g., CNTs can be produced by laser ablation, HiPCO  or high-pressure carbon monoxide, arc discharge, and chemical vapor deposition (CVD)). Examples of engineered nanomaterials include: carbon buckeyballs or fullerenes; carbon nanotubes; metal or metal oxide nanoparticles (e.g., gold, titanium dioxide); quantum dots, among many others.

Nanotube

The digital photograph above shows a nanotube, which is a member of the fullerene structural family. (NOTE:  A fullerene is a molecule of carbon in the form of a hollow sphereellipsoidtube, and many other shapes. Spherical fullerenes are also called Buckminsterfullerenes or buckeyballs, which resemble balls used in soccer.  Cylindrical fullerenes are called carbon nanotubes or buckeytubes.  Fullerenes are similar in structure to graphite, which is composed of stacked graphene sheets of linked hexagonal rings. ) Their name is derived from their long, hollow structure with walls formed by one-atom-thick sheets of carbon, called graphene. These sheets are rolled at specific and discrete angles where the combination of the rolling angle and radius defines the nanotube properties; for example, whether the individual nanotube shell is a metal or semiconductor.  Nanotubes are categorized as single-walled nanotubes (SWNTs) or multi-walled nanotubes (MWNTs). Individual nanotubes naturally align themselves into “ropes” held together by van der Waals forces, more specifically, pi-stacking.

The JPEG below shows a nanoplate material.

NANOPLATE

Nanoplate uses nanometer materials and combines them in engineered and industrial coating processes to incorporate new and improved features in the finished product.

USES OF NANO TECHNOLOGY:

Let’s look at today’s uses for nano technology and you can get a good picture as to where the field is going.

  • Stain-repellent Eddie Bauer Nano-CareTM khakis, with surface fibers of 10 to 100 nanometers, uses a process that coats each fiber of fabric with “nano-whiskers.” Developed by Nano-Tex, a Burlington Industries subsidiary. Dockers also makes khakis, a dress shirt and even a tie treated with what they call “Stain Defender”, another example of the same nanoscale cloth treatment.
    Impact: Dry cleaners, detergent and stain-removal makers, carpet and furniture makers, window covering maker.
  • BASF’s annual sales of aqueous polymer dispersion products amount to around $1.65 billion. All of them contain polymer particles ranging from ten to several hundred nanometers in size. Polymer dispersions are found in exterior paints, coatings and adhesives, or are used in the finishing of paper, textiles and leather. Nanotechnology also has applications in the food sector. Many vitamins and their precursors, such as carotinoids, are insoluble in water. However, when skillfully produced and formulated as nanoparticles, these substances can easily be mixed with cold water, and their bioavailability in the human body also increases. Many lemonades and fruit juices contain these specially formulated additives, which often also provide an attractive color. In the cosmetics sector, BASF has for several years been among the leading suppliers of UV absorbers based on nanoparticulate zinc oxide. Incorporated in sun creams, the small particles filter the high-energy radiation out of sunlight. Because of their tiny size, they remain invisible to the naked eye and so the cream is transparent on the skin.
  • Sunscreens are utilizing nanoparticles that are extremely effective at absorbing light, especially in the ultra-violet (UV) range. Due to the particle size, they spread more easily, cover better, and save money since you use less. And they are transparent, unlike traditional screens which are white. These sunscreens are so successful that by 2001 they had captured 60% of the Australian sunscreen market.  Impact: Makers of sunscreen have to convert to using nanoparticles. And other product manufacturers, like packaging makers, will find ways to incorporate them into packages to reduce UV exposure and subsequent spoilage. The $480B packaging and $300B plastics industries will be directly affected.
  • Using aluminum nanoparticles, Argonide has created rocket propellants that burn at double the rate. They also produce copper nanoparticles that are incorporated into automotive lubricant to reduce engine wear.
  • AngstroMedica has produced a nanoparticulate-based synthetic bone. “Human bone is made of a calcium and phosphate composite called Hydroxyapatite. By manipulating calcium and phosphate at the molecular level, we have created a patented material that is identical in structure and composition to natural bone. This novel synthetic bone can be used in areas where the natural bone is damaged or removed, such as in the treatment of fractures and soft tissue injuries.
  • Nanodyne makes a tungsten-carbide-cobalt composite powder (grain size less than 15nm) that is used to make a sintered alloy as hard as diamond, which is in turn used to make cutting tools, drill bits, armor plate, and jet engine parts.
    Impact: Every industry that makes parts or components whose properties must include hardness and durability.
  • Wilson Double Core tennis balls have a nanocomposite coating that keeps it bouncing twice as long as an old-style ball. Made by InMat LLC, this nanocomposite is a mix of butyl rubber, intermingled with nanoclay particles, giving the ball substantially longer shelf life. Impact: Tires are the next logical extension of this technology: it would make them lighter (better milleage) and last longer (better cost performance).
  • Applied Nanotech recently demonstrated a 14″ monochrome display based on electron emission from carbon nanotubes.  Impact: Once the process is perfected, costs will go down, and the high-end market will start being filled. Shortly thereafter, and hand-in-hand with the predictable drop in price of CNTs, production economies-of-scale will enable the costs to drop further still, at which time we will see nanotube-based screens in use everywhere CRTs and view screens are used today.
  • China’s largest coal company (Shenhua Group) has licensed technology from Hydrocarbon Technologies that will enable it to liquefy coal and turn it into gas. The process uses a gel-based nanoscale catalyst, which improves the efficiency and reduces the cost.  Impact: “If the technology lives up to its promise and can economically transform coal into diesel fuel and gasoline, coal-rich countries such as the U.S., China and Germany could depend far less on imported oil. At the same time, acid-rain pollution would be reduced because the liquefaction strips coal of harmful sulfur.”

CONCLUSION:

I’m sure the audience I attract will get the significance of nanotechnology and the existing uses in today’s commercial markets.  This is a growing technology and one in which significant R&D effort is being applied.  I think the words are “STAND BY” there is more to come in the immediate future.

 

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GRAPHENE

April 13, 2014


THE MATERIAL:

If you follow my posts you know I enjoy discussing all areas of technology especially new and exciting products, materials, processes, etc.   The material Graphene is certainly one of those.   Graphene is  a two-dimensional physical form of carbon.  Its amazing properties include being the lightest and strongest material, relative to all other carbon-based materials.    Graphene also has the ability to conduct heat and electricity better than just about any other substance, thereby enabling integration into a huge number of exciting applications.  It also conducts electricity better than copper and is 200 times stronger than steel but six times lighter.  It is almost perfectly transparent and only absorbs two percent (2%) light.  It is impermeable to gases, even those as light as hydrogen or helium, and, if that were not enough, chemical components can be added to its surface to alter its properties.  Graphene is one form — an allotrope — of carbon, the basis of all life on earth. More familiar carbon allotropes include diamonds and graphite. What makes it unique is its thinness — at one atom thick it is as good as two-dimensional. Its flexibility means that it could potentially be used for flexible or wearable devices.  The carbon represents a single layer of carbon that is bonded together in a repeating pattern of hexagons. Graphene is one million times thinner than paper; so thin that it is actually considered two dimensional. A digital photograph of the lattice-structure is given as follows:

LATTACE STRUCTURE

DISCOVERY:

About ten years ago, the Dutch-British physicist Andre Geim stumbled across a substance that would revolutionize the way we understand matter and win him and his colleague Kostya Novoselow the 2010 Nobel Prize for Physics.  That material was graphene — a one atom thin substance.  According to Dr. Geim;   “It’s the thinnest material you can get — it’s only one atom thick. A tiny amount can cover a huge area, so one gram could cover a whole football pitch. It’s the strongest material we are aware of because you can’t slice it any further. Of course, we know that atoms can be divided into elementary particles, but you can’t get any material that is thinner than one atom, or it wouldn’t count as a material anymore”.

 

APPLICATIONS:

Because of its range of extraordinary properties, people are considering using graphene in a myriad of different applications. For example, because graphene is so strong, people want to use it to reinforce plastics, making them conductive at the same time. People are also considering using it to go beyond silicon technology and make our integrated circuits even denser and speedier. Those are just a few examples.   Typically it takes 40 years for a new material to move from an academic lab into a consumer product, but within less than ten years graphene has jumped from a laboratory environment to an industrial lab and now there are pilot products all over the world. Governments and probably more than 100 companies are spending billions on researching these materials.  So, it probably deserves the superlative of being the fastest developing material we know today.

Other applications include:

Solar cells: Solar cells rely on semiconductors to absorb sunlight. Semiconductors are made of an element like silicon and have two layers of electrons. At one layer, the electrons are calm and stay by the semiconductor’s side. At the other layer, the electrons can move about freely, forming a flow of electricity. Solar cells work by transferring the energy from light particles to the calm electrons, which become excited and jump to the free-flowing layer, creating more electricity. Graphene’s layers of electrons actually overlap, meaning less light energy is needed to get the electrons to jump between layers. In the future, that property could give rise to very efficient solar cells. Using graphene would also allow cells that are hundreds of thousands of times thinner and lighter than those that rely on silicon.

Transistors: Computer chips rely on billions of transistors to control the flow of electricity in their circuits. Research has mostly focused on making chips more powerful by packing in more transistors, and graphene could certainly give rise to the thinnest transistors yet. But transistors can also be made more powerful by speeding the flow of electrons — the particles that make up electricity. As science approaches the limit for how small transistors can be, graphene could push the limit back by both moving electrons faster and reducing their size to a few atoms or less.

Transparent screens: Devices such as plasma TVs and phones are commonly coated with a material called indium tin oxide. Manufacturers are actively seeking alternatives that could cut costs and provide better conductivity, flexibility and transparency. Graphene is an emerging option. It is non-reflective and appears very transparent. Its conductivity also qualifies it as a coating to create touch-screen devices. Because graphene is both strong and thin, it can bend without breaking, making it a good match for the bendable electronics that will soon hit the market.

Graphene could also have applications for camera sensorsDNA sequencinggas sensingmaterial strengtheningwater desalination and beyond.

The published paper fromGeim and Novoselov’s was wildly interesting to other scientists because of graphene’s  strange physical properties.  Electrons move through the material incredibly fast and begin to exhibit behaviors as if they were massless, mimicking the physics that governs particles at super small scales.

According to their article published in Scientific American,  “That kind of interaction inside a solid, so far as anyone knows, is unique to graphene,” wrote Geim and another famous graphene researcher, Philip Kim, in a 2008 Scientific American article. “Thanks to this novel material from a pencil, relativistic quantum mechanics is no longer confined to cosmology or high-energy physics; it has now entered the laboratory.”

DRAWBACKS:

Every new technology is somewhat evolutionary instead of revolutionary.  For this reason, obstacles will need to be overcome for mass production and use.

The material is still in an infantile stage compared to developed materials like silicon and ITO. In order for it to be widely adopted, it will need to be produceable in large quantities at costs equal to or lower than existing materials. Emerging roll-to-roll, vapor deposit and other production techniques hint that this is possible, but they’re not yet ready to bring graphene to every mobile device screen out there. Researchers will also need to continue to work at improving  graphene’s transparency and conductivity in its commercial form.

PRODUCTION

While graphene shows promise for transistors, it has a major problem: It can’t switch the flow of electricity “off” like materials such as silicon, which means the electricity will flow constantly. That means graphene can’t serve as a transistor on its own. Researchers are now exploring ways to adjust it and combine it with other materials to overcome this limitation. One technique involves placing a layer of boron nitride–another one-atom-thick material–between two layers of graphene. The resulting transistor can be switched on and off, but the electrons’ speed is slowed somewhat. Another technique involves introducing impurities into graphene.

Graphene may also be emerging too late for many of its possible applications. Electric car batteries and carbon fiber could be made with graphene, but they already rely on activated carbon and graphite, respectively — two very inexpensive materials. Graphene will remain more expensive for the time being, and may never be inexpensive enough to convince manufacturers to switch.

The world is only a decade into exploring what it can do with graphene. In contrast, silicon has been around for nearly 200 years. At the pace research is moving, we could know very soon if graphene will become ubiquitous or just another step in discovering the next wonder material.

I welcome your comments.

 

 

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