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​