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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