4.2.4 Bulk and surface properties of matter including nanoparticles

what are nanoparticles

Nanoscience refers to structures that are 1–100 nm in size, of the order of a few hundred atoms. Nanoparticles, are smaller than fine particles (PM2.5), which have diameters between 100 and 2500 nm (1 x 10-7 m and 2.5 x 10-6 m). Coarse particles (PM10) have diameters between 1 x 10-5 m and 2.5 x 10-6 m. Coarse particles are often referred to as dust.

uses of nanoparticles

1. They​ ​have​ ​a​ ​high​ ​surface​ ​area​ ​to​ ​volume​ ​ratio,​ ​and​ ​therefore​ ​would​ ​make good​ ​catalysts.
2. They​ ​can​ ​also​ ​be​ ​used​ ​to​ ​produce highly​ ​selective​ ​sensors.
3. Nanotubes​ ​could​ ​make​ ​stronger, lighter​ ​building​ ​materials.
4. New​ ​cosmetics,​ ​e.g​ ​sun​ ​tan cream​ ​and​ ​deodorant.​ ​They

make​ ​no​ ​white​ ​marks and are not oily


5. Lubricant​ ​coatings,​ ​as​ ​they reduce​ ​friction.​ ​These​ ​can​ ​be used​ ​for​ ​artificial​ ​joints​ ​and gears.
6. Nanotubes​ ​conduct​ ​electricity,​ ​so​ ​can​ ​be​ ​used​ ​in​ ​small​ ​electrical​ ​circuits​ ​for computers.
7. silver nanoparticles have antibacterial properties- can be added to polymer fibres that are then used to make surgical masks and wound dressings and they can be added to deodorants

disadvantages of nanoparticles

1. there​ ​are​ ​some​ ​concerns​ ​that​ ​nanoparticles​ ​may​ ​be toxic​ ​to​ ​people.​ ​
2. They​ ​may​ ​be​ ​able​ ​to​ ​enter​ ​the​ ​brain​ ​from​ ​the​ ​bloodstream and​ ​cause​ ​harm.

nanoparticles used in suncreams

have been shown to be better than the materials in traditional sun creams at protecting skin from harmful UV rays

give better skin coverage than traditional suncreams

they may damage cells, when washed away they damage the environment

relationship between SA and volume

As the side of cube decreases by a factor of 10 the surface area to volume ratio increases by a factor of 10

how to work out SA : V ratio

sa/ v

as the particles decrease in size, the size of their surface area increases