Nanoscience Chemistry Study Note

Fullerenes

Fullerenes: A group of allotropes of carbon, made up of balls, 'cages' or tubes of carbon atoms  

This is a type of fullerene known as a Buckminsterfullerene or 'buckyball'.  They can be made with 60, 70,76 or 80 carbon atoms. Because they have a closed structure, they can be used to entrap other molecules. This can be useful for: Carrying drugs for delivery to specific sites in the body In cosmetics, where they can absorb harmful radicals

Carbon Nanotubes

Carbon nanotubes are another type of fullerene. Molecular-scale tubes of graphite-like carbon. Among the stiffest and strongest fibres known - due to covalently bonded carbon hexagonal rings Excellent conductivity - due to free electrons Current uses: Atomic force microscopes Bone-tissue scaffolding Cancer treatment To make bulk materials for use in bicycle components and boat hulls To make bulk materials for use in epoxy-resins for bonding high performance components in wind-turbines and sports equipment Proposed further uses: Connections inside miniature electronic circuits

Nanoparticles

Nanoparticles: Particles between 1 and 100 nanometers in size. In nanotechnology, a particle is defined as a small object that behaves as a whole unit with respect to its transport and properties.  Nanoparticles sometimes have different properties from their bulk material, because they have a very large surface area for their size compared to normal particles.   Silver nanoparticles 1. Medical uses Silver is commonly used for its antibacterial properties, particularly to treat external infections Silver ions irreversibly damage key enzymes in the cell membranes of the microorganisms Silver nano particles have a much greater anti-bacterial action than normal silver particles, because their tiny size means they can get to places normal particles cannot.  They might even be able to enter living cells. 2. Clothes Silver nanoparticles have been incorporated into the fabric of clothes in order to kill the bacterial build up that causes odours. Dangers of silver nano particles: We do not yet fully understand the consequences of using nano particles. There is no direct evidence that they are harmful, but we do not know for certain that they are harmless either.  Some scientists are concerned especially by the effect they could have on the environment were they to find their way into delicate ecosystems or municipal waste water systems that depend on bacteria. The Royal Comission of Environmental Pollution recommended against their use in clothes in 2008.

Titanium dioxide

Titanium dioxide:  A white solid used in house paint and the coating of some chocolates 1. Sunscreen Titanium dioxide nano particles are so small that they do not reflect visible light - they are invisible Used in sunscreens as they block UV light without appearing white on the skin 2. Food Found in some food products such as white icing

Shape Memory Polymers

Polymers that can regain their shape when heated When first heated, the polymer softens and can be deformed On cooling it retains that deformed shape If heated again, it can 'remember' its original shape, and will return to that shape This property is called shape retention Uses: Sealing around window frames, manufacture of sports wear such as helmets and gum shields

Shape Memory Alloys

Metal alloys that regain their original shape when heated, like shape-memory alloys Nickel/titanium alloy (Often known as nitinol) and copper/aluminium/nickel alloys These alloys are also pseudoelastic (They appear to be elastic) Uses: Dental frames, to replace hydraulic systems in the aeronautical industry, surgical wires that replace tendons