I am attempting to use the process described in the link below. Briefly, one spin-coats PMMA onto the substrate that has nanostructures on it. Then put PDMS on top and add a few drops of water which is supposed to allow the PMMA to separate from the substrate. Then use PDMS as mechanical support to transfer to clean substrate. My initial substrate is SiO2 with some tape residue remaining from mechanical exfoliation. I want to transfer to clean SiO2.
I am unable get the PMMA to separate from the substrate as a film. It resembles more like a paint which I can only scratch off. I suspect something is wrong with the PMMA solution. I use 950k 2% in chlorobenzene, something we already have in our lab. The paper uses 3% in dichloromethane, but I was told it will not make a difference. I have tried different PMMA spin rates (1000-3000rpm) and annealing temperatures (50-80C) with no success.
Any advice will be much appreciated
http://pubs.acs.org/doi/abs/10.1021/nn501779y?src=recsys&journalCode=ancac3
Thank you Dr. Tsambani. I have already seen the data sheet. It allows me to estimate film thickness for chlorobenzene and anisole solutions that Microchem makes but not for other solvents. Clearly my film is too thin (.2-2micron) to be able to handle with tweezer, but I hope it can still made to float on top of water then transferred by switching out substrate underneath and lowering the water level. Do you know if there is any advantage of making our own PMMA solution with dichloromethane?
Hi Psi200, No I was not able to peel PMMA film so I switched to polystyrene dissolved in toluene. I've had much better success with that.
Hi Timofy Golubev. I am not sure what your substrate is.Because, if you use a substrate with oxide layer, then you might etch it in KOH (at more than 1000C) and peel it off easily. But anyways, i would suggest you to try adding a water-soluble Polyvinyl Alcohol (PVA) layer between the polymethyl-methacrylate (PMMA) and the 2D material film or flakes. You may find the details of this transfer method in the attachment. Wish you good luck
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