I dissolve graphene oxide in DMF and water but it soon settles at the bottom.
To repeat György - GO is not dissolved in any of the liquids mentioned above it can only be dispersed. Depending on the (agglomerate) size, density difference and liquid viscosity particles (agglomerates) will settle. Therefore you need strong interaction with the molecules of the liquid (wettability), low as possible density difference, high as possible viscosity. For real case you need the best compromise.
It is not a solution in the classical sense of the word. It is a dispersion. There are various ways to stabilize a dispersion (surfactants, polymers etc.)
http://www.sciencedirect.com/science/article/pii/S0008622312005763
http://arxiv.org/ftp/cond-mat/papers/0703/0703515.pdf
http://www.hindawi.com/journals/jnm/2010/528235/
See much more under Google "graphenes suspension stability"
Ethanol is good solvent to make stable dispersions, chloroform as well but it's more toxic!
knowing the size and density of the particles you can calculate this your self with Stokes law.
You can chechk our latest publication ''Dispersion behaviour of graphene oxide and reduced graphene oxide''
Acetone is also used to dissolve GO. And it seems better than Ethanol according to the paper published by Dimitrios Konios and co. The link to the paper is given above in this discussion.
To repeat György - GO is not dissolved in any of the liquids mentioned above it can only be dispersed. Depending on the (agglomerate) size, density difference and liquid viscosity particles (agglomerates) will settle. Therefore you need strong interaction with the molecules of the liquid (wettability), low as possible density difference, high as possible viscosity. For real case you need the best compromise.
what happens if we mix a GO dispersed in water (mostly exfoliated GO or graphene) to ethanol . Will they restack or remains stable as exfoliated one
The dispersity of GO depends on the oxygen functional group. More oxygen content leads to higher disersity in water or DMF. Usually 1-4 mg GO per one mL water can form well dispersion.
Methyl ethyl ketone (MEK)
N,N—dimethyl acetarnide (DMA)
N,N—dimethyl formarnide (DMF)
N-methyl-2-pyrrolidone, NMP
and many more...
As Mr. Banhegyi suggested, Google Scholar, Web of Science, etc. would be perhaps good points to start from.
This paper can be useful too:
http://www.sciencedirect.com/science/article/pii/S135902941500093X
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