Exfoliation is the separation of layered materials into inidividual sheets. It therefore concerns materials having a 2D structure: mica, graphite, double layered hydroxydes, clays, chromium chloride, etc. Exfoliation of clays produce high surface area-materials, having the property of purifying the skin for example when applied onto the body, exfoliation of a kind of mica produces vermiculite, used as cushioning material or as thermal insulator, and exfoliation of graphite produces graphene. Therefore, it is a process of highest importance in many applications.

Alain

Thanks Alain,

Do you know the methods that usually used to exfoliate?

Exfoliation mechanisms strongly depends on the layered material considered: water can be enough for some clays, which swell tremendously as soon as they are wetted, whereas others also require the help of high temperature. In the latter case, the vaporisation of what was intercalated push the layers apart, hence the exfoliation (e.g. vermiculite). For graphite, a redox reaction is required (through chemistry or electrochemistry), followed by a quick heat-treatment to vaporise the intercalate and therefore produce exfoliated graphite.

Alain

Is there a list for all layered materials?

Graphite, MoS2, WS2, double-layered hydroxydes, phyllosilicates, talc, clays, CrCl3, etc ...

Alain

Search for coleman papers, which are the best and explains the simplest way (sonication ) for exfoliating all 2D materials.