You could also try playing with pH to detach the PEG from the AuNPs, centrifuge, wash, and redisperse in another polymer or capping agent.
Thank you everyone for your answers.
Actually, I should have mentioned it before but the objective of my experiment is to make micro-meter sized triangular or hexagonal Gold flakes with thickness of about 10-50 nanometers. I have attached the reference here. I tried centrifuging at the speed of 60000 RMP for 2 minutes but separation was not perfect. I was reluctant to use higher speed and for longer time because that may destroy the shape of the flakes. As mentioned in the journal, I tried using ethanol and water, and wash and filter it but even with that, there was a huge loss of materials. So, I was just wondering if there is any other way I could do it.
Thank you all again.
Washing the reaction mixture with ethanol/methanol followed by centrifugation may help.
Dear Parva,
if you have an idea about the particle size you should first calculate the time needed for the desired separation based on Stokes law. Not the rotor speed but the acceleration is what counts. Obviously in the high viscosity glycol it would be a difficult task. Therefore as suggested centrifugation of a mix with large content of low viscosity solvent like ethanol would be preferable. Maybe addition of a hydrocarbon like heptane to ethanol in a second step may assist in the flake production.
I would like to add a question. If the solvent was acetic acid instead of PEG - would it be possible to evaporate it under vacuum and thus separate the nanoparticles?
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