In this paper we describe a method to separate an existing dispersion with mean flake length of ~1 μm into fractions, each with different mean flake size
2011
Key concepts
Scholarcy highlights
- Liquid phase exfoliation of graphite to give graphene has received a lot of attention in recent years
- If one chooses 500 rpm to remove only the crystallites, the result will be the initial supernatant with only small flakes, the redispersed centrifuged sediment with all other flake sizes and a second sediment containing the crystallites
- The result will be the initial supernatant with only small flakes, the redispersed, centrifuged sediment with medium sized flakes and a second sediment with large flakes and crystallites
- We have demonstrated that controlled centrifugation can be used to separate graphene flakes by size
- To achieve this, we first need to determine the baseline flake size distribution achieved using standard dispersion techniques. To do this we sonicated graphite powder in 500ml of NMP in a sonic bath for 168 hrs. This was centrifuged at 500 rpm for 45 minutes and the top 80% of the supernatant pipetted off
- Centrifugation at a lower rate results in a dispersion of slightly larger flakes and the rejection of the rest. Repeating this procedure a number of times results in the separation of the original dispersion into a number of fractions each with different mean flake length, in this case from ~1 to ~3.5 μm. We have demonstrated this procedure for solvent exfoliated graphene, it could be extended to surfactant exfoliated graphene or otherexfoliated layered compounds
Need more features? Save interactive summary cards to your Scholarcy Library.