Nanotechnology

Question 1

Define nanotechnology

Answer 1

Nanotechnology involves the study of nanoparticles and structures as well as their potential use.

Question 2

Define nanoparticles

Answer 2

Nanoparticles are particles with at least one dimension in the 1-100 nanometre range.

1nm = 1 × 10^-9 metres

Question 3

Potential applications on everyday materials

Answer 3

• Nanosilver: socks, children’s toys, eating utensils, refrigerators, cosmetics
• Carbon black: tyres
• lithium ion batteries
• sunscreen (zinc-oxide nanoparticles)

Question 4

Potential applications on electronics

Answer 4

computer out of carbon nanotubes → smaller, faster and more energy efficient than silicon based computers

graphene -> computer chips

Question 5

Potential applications on medical/therapeutic uses

Answer 5

• surgical bandages, instruments and masks made out of nanosilver
• detection and treatment of cancer -> dendimers

Question 6

Potential applications on energy

Answer 6

lithium ion batteries → graphite, carbon-silicon nanocomposite
solar panels -> fullerenes and graphene

Question 7

How and why do nanoparticles differ from the bulk materials of which they are made

Answer 7

• Properities like SA:V ratio changes that allow surface area effects (a.k.a. quantum effects)
• this dramatically alters the optical, electrical and magnetic properties of a material

e.g. turning electrical insulators into superconductors; making visible substances seemingly invisible (zinc oxide)

Question 8

Graphene structure

Answer 8

a single layer sheet with same arrangement in hexagons as those stacked in graphite

Question 9

Graphene bonding

Answer 9

has delocalised electrons
covalent bonding

Question 10

Graphene properties

Answer 10

• high electric conductivity
• extremely strong and tough
• every carbon atom is available for reaction from two sides bc it is one layer

Question 11

Graphene applications

Answer 11

• in organic photovoltaic cells
• reinforce composite materials bc it’s strong
• replace silicon in computer chips & circuits
• desalination in plants

Question 12

Bulkminister fullerenes structure

Answer 12

roughly spherical group of 60 carbon atoms arranged in a series of 12 pentagons and 20 hexagons; similar to soccer ball

Question 13

Bulkminister fullerenes bonding

Answer 13

• 3 covalent bonds to each carbon atom
• strongly bonded to one another but little attraction between neighbouring C60 molecules
• has delocalised electrons

Question 14

Bulkminister fullerenes properties

Answer 14

• can conduct electricity (semiconductor)
• extremely large surface area
• low melting point, soft

Question 15

Bulkminister fullerenes application

Answer 15

making solar panels (photovoltaic cells)

Question 16

Carbon nanotubes structure

Answer 16

• a sheet of graphene rolled into a cylinder and can be open or capped at the ends by half a fullerenes molecule
• diameter 1 nanometre or more
• can be multi-walled

Question 17

Carbon nanotubes bonding

Answer 17

• strong carbon to carbon bonds
• covalently bonded into interlocking hexagonal arrangements

Question 18

Carbon nanotubes properties

Answer 18

• exceptional strength and stiffness
• flexible and light
• excellent conductors of semiconductors of electricity depending on their dimensions and symmetry
• good thermal conductivity

Question 19

Carbon nanotubes applications

Answer 19

• computer
• electronic semiconductor devices (translators, diodes, computing applications)
• batteries

Question 20

Nanosize silver bonding

Answer 20

metallic bonding
delocalised electrons

Question 21

Nanosize silver properties

Answer 21

antibacterial and antifungal -> silver releases ions

are increased in nano form bc more surface area = stronger effect

Question 22

Nanosize silver applications

Answer 22

• surgical bandages, instruments and masks
• socks, children’s toys, eating utensils, refrigerators, cosmetics

Question 23

Precautionary principle

Answer 23

• nanoparticles’ properties differ significantly from their parent material due to the quantum effects → can’t assume that carbon nanotubes are safe just because bulk material carbon is safe
• currently, nothing has been proven to say that nanoparticles are dangerous but we should still assume it’s possible to have some

Question 24

Potential environmental and health risks associated with nanoparticles

Answer 24

• CSIRO scientists are looking into sunscreens, and if zinc-oxide nanoparticles are safe
  
  • whether it can penetrate skin → initial studies showed small amounts can be detected in blood and urine → not clear if it has any affects though
  • long-term effects
  • if it affects environment
  • most recent research says that cells can break down the nanoparticles
• silver nanoparticles can overtime be released into the aquatic environment (washing clothes)

Question 25

Nanocomposites

Answer 25

Bulk materials + nanosized particles *to enhance properties of mechanical strength, electrical/thermal conductivity and catalytic/optical improvements* e.g. lithium ion batteries, plastics

Question 26

Lithium ion batteries

Answer 26

graphite electrodes means it's brittle and low conductivity can add graphene sheets or carbon nanotubes

Question 27

Adding nanoparticles to plastic can increase:

Answer 27

- stiffness by 50% - mechanical strength by 20%

Question 28

Carbon-Silicon Nanocomposite Electrodes

Answer 28

*effective graphite replacements* Silicon anode advantages: ~10x more energy storage than carbon **Problem with pure silicon:** Expands/contracts during charging → causes crumbling **Carbon-silicon nanocomposite:** Avoids expansion issue Maintains high energy capacity and good conductivity

Question 29

Example of construction

Answer 29

- Brick dust and glass fibres are hazardous when inhaled in fine particulate form, but safe in bulk - Suggests that airborne nanoparticles could pose similar inhalation hazards

Question 30

How is the government helping with safety of nanoparticles?

Answer 30

Australian Government completed a 4-year NETS study Aimed at creating guidelines for nanotechnology industry Other countries are also considering regulation and legislation

Question 31

Top-down fabrication

Answer 31

- starts with a material in a larger scale than required - material is slowly removed or size is reduced

Question 32

Bottom-up fabrication

Answer 32

- still in early stages of development - individually selected atoms or molecules are successively built up until material is formed

Question 33

Limitations of Optical microscopes

Answer 33

- Use visible light to magnify objects (400–750 nm wavelength) - Can't view atoms (< 0.5 nm) or nanoparticles (1–100 nm) - Limited by diffraction → need non-optical methods for nano-scale imaging

Question 34

Types of imaging for nanoparticles

Answer 34

- **Transmission Electron Microscope** -> electron beam to view smaller particles - Scanning Electron Microscope -> scans surface with narrow electron beam - Scanning Tunnel Microscope -> ultra-fine needle tip to 'feel' surfaces - **Atomic Force Microscope** -> uses scanning tip to measure forces between tip and surface to pick up atoms or nanoparticles

Question 35

Manufacturing nanoparticles examples

Answer 35

- Ball milling - Electric Arc Discharge - CNTs - Laser Ablation - CNTs - Atom-by-Atom Construction

Question 36

Electric Arc Discharge

Answer 36

- common for CNT's - Involves a large DC current between graphite electrodes (anode & cathode) in an inert atmosphere

Question 37

Laser Ablation

Answer 37

Produces high-powered laser pulses to **vapourise graphite** in an inert environment

Question 38

Quantum Dots

Answer 38

*e.g. Cadmium Selenide* example of quantum effect - atoms can now dissolve or exhibit a range of colours depending on particle size **application:** future technology of quantum computing