What are Nanomaterials?

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Nanomaterials: 1-100 nm

• Nanomaterials have at least 1 dimension measuring less than 100 nm.
• They are generally man-made, inorganic materials.
• To explain, lets look at carbon-based nanomaterials.

Buckyballs

Buckyballs are spherical nanomaterials with all three dimensions confined at the nanoscale.

• Measuring 1 nm in diameter.

• Carbon atoms in buckyballs have the same structure of pentagon and hexagon faces as a soccer ball.
• They are probably the only nanomaterial with a defined molar mass (of 720 g/mol).

Buckyballs

• Buckyballs  were the first. carbon-based nanomaterial
• Discovered in 1985 by James R. Heath, a grad student at Rice University. 
• 11 years after,  in 1996, the professors involved shared the Nobel Prize in Chemistry for this discovery.

Sample application:                       

• used in next-generation organic solar cells.

Microscopy of buckyballs

Carbon Nanotubes

• Cross section or diameter is ~1-3 nm.
• They are a pipe 1 atom thick.
• However, nanotube length can be quite long exceeding a micrometer.

Characteristics:

• 150 times stronger than steel
  (1/6 of the weight).
• Flexible.
• Good conductors of electricity and heat.
• Diameter: 1-3 nm.

Carbon nanotubes are tubular / cylindrical nanomaterials with
2 dimensions at the nanoscale.

Carbon Nanotubes

• Discovered by Sumio Iijima of Nippon Electric Company (NEC), Japan, in 1991. 
• It was an accident!: They were trying to make buckyballs but instead observed unusual carbon fibers which turned out to be nanotubes.
• Under microscope they look like hair, thin fibers, or a bowl of spaghetti.

Sample application:

• used in application of flexible electronic displays, next generation of transistors, solar panels, stealth paint (cloaking devices), cancer treatment/therapy.

Graphene

• It is a sheet only 1 carbon atom thick.
• Lateral dimensions can be in the micro or even in the millimeter scale.

Characteristics:

• Excellent conductors of electricity and heat.
• Extremely strong. 
• Flexible.

Graphene is a planar nanomaterial with 1 dimension confined at the nanoscale.

Graphene

• Graphene is a derivation of graphite (pencil lead).
  • Graphite is multiple layers of graphene stacked on top of each other.
• “Re-discovered” by A. Geim and K. Novoselov in 2004, two researchers at the University of Manchester.
• Developed a practical “scoth tape” technique to pull apart the layers, isolating individual sheets of graphene from bulk graphite.
  • Won the 2010 Nobel Prize in Physics.

Sample application:

• Applications are very similar to those of carbon nanotubes.
• Also will be used for flexible displays, sensor devices, high-performing batteries, etc.

Carbon-based Nanomaterials

Nanotubes, graphene, and buckyballs are new allotropic forms of carbon. 

• What is an allotrope?
  • ​Different structural arrangement of the same element resulting in different forms or materials.

• Allotropes of Carbon:
  • Diamond
  • Graphite
  • Amorphous (coal)
  • Buckyballs
  • Nanotubes
  • Graphene
  • Carbyne

All of these are made entirely of carbon atoms, but different structural arrangement of the atoms result in different materials

carbon-based

nanomaterials

Carbon-based Nanomaterials

Structural difference give the new, nano allotropes different properties from other forms of carbon. Example:

• In diamond all carbons are bound to 4 other carbon atoms, but our nano-material structures have carbon bound to 3 other carbon atoms.

• ​By only being bound to 3 other C's, the nano-based materials have C atoms with a free electron pair - this is what makes nanotubes and graphene good conductors of electricity vs. diamond.

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Structure of Diamond

Structure of graphene, carbon nanotubes, and buckyballs

Where Can I Find Them?

• Nanomaterials can be purchased online, like everything else.
• Ex: Carbon Solutions offers a variety of nanotubes and graphene.
• Compare pricing: 1 gram of purified nanotubes = 7x's more than gold;
  1 gram of functionalized nanotubes = 25x's more than gold.
• We need better processes to make the materials cheaper!
  • Graphene for example, could be used in tons of applications if only there was a good, cost-effective way to make lots of it.

Carbyne

• Carbyne is the 4th type of carbon-based nanomaterial, but so far is only theoretical.
• Carbyne is a single chain of double-bonded carbon atoms:

• Been studied through simulations & computations.
• It is predicted to be the strongest material ever.
  • but, we cannot figure out how to make it.
• We need someone to figure out the mystery!

  Model of  a carbyne rope

Carbyne is predicted to be shaped as a rope structure

Non-Carbon Nanomaterials

• Carbon-based nanomaterials are unique and often talked about in their own category. 
• There are many other types of nanomaterials made from other elements or molecules.

Nanowires

Nanowires = “wire-like” structures with 1-100 nm cross-section.

• Made of copper, metals, metal oxides.

Examples of copper nanowires:

Sample application:

• Electronics, fundamental components (super-capacitors, transistors), sensor technologies.

Bulk copper wire

Nanoparticles

• Have been made from all kinds of materials.
  • Metals, metal oxides (e.g., gold, silver)…
• Have a variety of structures
  • Nano-”shells” or nano-”onions” (with different layers of materials).

Nanoparticles are small aggregates/clusters of atoms with dimensions between 1-100 nm.

• They might be 1-2 nm in diameter up to much larger structures (100 nm in diameter or more…).

Nanoparticles

Generally spherical in shape but, but can have many different faces depending on the size.

• The smaller, the more faces it tends to have (more polygonal, less smooth).
• The larger the structure, the smoother it tends to be.

Sample application:

• Depends on nanoparticle composition 
• anti-bacterials, personalized medicines, cosmetics, molecular imaging in radiology, and more...

Overview of Nanomaterials: Carbon

• Buckyballs- soccer ball-shaped carbon molecules. 
• Nanotubes- pipe- or tube-like carbon structures, 1-atom thick and hollow inside.
• Graphene- a flat, continuous sheet of carbon atoms, 1-atom thick.
• Note: this table does not include carbyne, which is currently only theoretical. 

Overview of Nanomaterials: Other

• Nanowires- wire-like materials.
• Nanoparticles- quasi-spherical clusters of a small number of atoms.
• Nanowires and nanoparticles are typically formed from:
  • Metals - Iron, Gold, Silver, Nickel, etc.
  • Metal oxides - Titanium dioxide, Iron oxide, etc.
  • Semiconductors - Silicon, Indium phosphide, etc...

Learn More: Videos to Watch

Carbon Nanotubes: Watch how nanotubes are made and some interesting properties they have as they are played with in the lab.

Learn More: Videos to Watch

Graphene:
The science that makes it so special.

Graphene:
Applications of the next revolutionary material.

In-Class Assignment

1. Name the 3 most common types of carbon-based nanomaterials?
2. What is a typical diameter of single-walled carbon nanotubes? And buckyballs?
3. Nanoparticles can be made of…..
4. Referring to the Periodic Table and what you know about nanoparticles, name 3 elements that are not typically used to make nanoparticles.
5. How many orders of magnitude does the size of nanoparticles span?
6. Nitrogen nanowires are common. True or False?
   

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To learn more about nanotechnology, visit omninano.org​