I have a trouble now. I need to use a relatively gentle method to completely remove ODE without damaging the surface ligand(in my case oleic acid coated CuInS2 quantum dots with only ODE as the solvent). add in Ethanol,acetone or Acetonitrile Centrifuge several times at high speed will damage the surface ligand or alloy shell(ZnS-CuInS2). So, how should I modify my purification method?
Hi Yong Huang
I would try to use a non-polar solvent, like cyclohexane or iso-octane or heptane. This gives you a better chance of selectivity between the octadecene and the oleic acid salt.
Also, even though I don't have a clear picture of your experimental setup, I think if you have trouble with fast centrifugation the answer could be slow centrifugation, for a longer time, and if needed - repeat it with fresh solvent.
Emanuel Cooper thank you for all your assistance, I still have a question about the three non-polar solvents you mentioned can be selective for 1-octadecence and oleic acid salt, I can't understand it well, or can you please provide relevant literature. thank you very much.
Hi Young Haung,
All the solvents mentioned above have similar selectivity to octadecene. The number of these solvents also includes hexane, petrol ether, methylcyclohexfne, benzene, toluene etc.
Can you suspend in a dense, polar solvent (e.g. nitromethane), and adsorb the octadecene onto a hydrophobic surface? Beads or microparticles of polyethylene or polystyrene, for example, should bind the olefin, and it should be possible to remove them by flotation or very mild centrifugation.
Less-gentle methods include filtration, which would permit the use of less-dense solvents, or passage of the suspension through a column of the polymer particles. Along the same lines, gel filtration media (Sephadex LH-20) should retard the olefin while letting the quantum dots pass untouched.
James Demers 's suggestion makes sense. However, I think Yong Huang is concerned about possible interaction of the inorganic surfaces with the polar solvent. In case that turns out to be a problem, here's a variation: Use a perfluorinated solvent, which if of low MW will probably dissolve enough octadecene; AND use beads or microparticles of PE or PS as suggested. It is highly likely that the octadecene partition coefficient between the perfluorinated solvent and the waxy beads will be favorable to the extraction Dr. Demers suggests.
Dear Yong Huang I just came across your very interesting technical question. The removal of residual 1-octadecene seems to be a rather common problem when working with nanomaterials. In this context it might be worth having a look at the answers given to the following closely related questions:
How can I remove 1-octadecene after growing nanoparticles?
https://www.researchgate.net/post/How_can_I_remove_1-octadecene_after_growing_nanoparticles
(24 answers)
and
Removal 1-octadecene
https://www.researchgate.net/post/removal_1-octadecene
(4 answers)
Also please see the following relevant literature reference:
The Trouble with 1-Octadecene; Polymerization During Nanocrystal Synthesis
https://s3-eu-west-1.amazonaws.com/itempdf74155353254prod/8832320/The_Trouble_with_1-Octadecene__Polymerization_During_Nanocrystal_Synthesis_v1.pdf
(see attached pdf file)
I hope this helps. Good luck with your work and best wishes,
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