I try to make a thin film of coating PEG solution on glass substrate, but the resulted thin film contains many spots and unordered. Can anyone suggest to me the quantity of PEG that added to water to be suitable as thin film?
Hi Karar,
Let me direct you to an expert in this field,
you can raise the question to [email protected], she has the answere.
Let me know if this is helpful.
Regards,
Dinesh
Dear Karar
Can you dissolve a volume of 0.4ml Poly ethylene glycol in 20ml of 2-methoxy ethanol and stir it for 1 hour. Please, see attached file.
Karar,
I would advise you with a few things:
1) Yonkowski and Soane, Journal of Applied Physics, 72, 725 (1992) is a very good analysis of spin coating.
2) When you spin coat, the first thing that happens is most of the solution flies off the edge, and what remains is a thin wet layer on the substrate. That is the first stage. In the second stage, that wet layer dries down. The thickness of the wet layer at the end of stage one depends on the solution viscosity. So you need to adjust the weight percent loading in conjunction with the molecular weight of the PEG to get to the desired thickness.
3) Your PEG should be dissolved for a few days prior to spin coating. Apply the solution to the substrate via a syringe, with a syringe filter attached to the end. A one micron filter will trap most of the dust. Use a second pipette to suck back up any bubbles that are on the surface of the solution when it is on the substrate.
4) You will not avoid the Maragoni defect in the center of the plate. Sometimes annealing in an oven (for PEG, set the oven to 80 C) will help.
Good luck!
Jeff
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