Hello,
I am making a graphene oxide/polymer composite membrane using spin-coating. When the precursor solution is made (blending and sonication of polymer with graphene oxide, followed by centrifugation), I get a clear solution that is stable for over a week. However, when spin-coated, the graphene oxide agglomerates, and I end up with poor membrane performance. I tried different spin coating techniques, precursor solution ratios, and many other ways but I seem to face the same problem. Any idea what is causing this?
I had used polydopamine coating for preventing agglomeration of Titanium oxide nanoparticles. There are many other ways. Go through this article:
https://www.researchgate.net/publication/342785932_Novel_polyvinyl_alcohol_nanofiltration_membrane_modified_with_dopamine_coated_anatase_TiO2_core_shell_nanoparticles
I was also facing this problem in my research. Thank you Faiz Khalid!
Faiz Khalid thanks for that. I know I may need to functionalise my GO with something like APTS. Was wondering if there was a method not needing functionalisation, or if there is a spin-coating factor that can reduce agglomeration (precursor solution temperature, spin speed...etc.).
I have synthesized Polycarbazole /Tin oxide nano-composites through in situ chemical polymerization method. but i got nodular and network like structure. once try by changing solvent media which you have dissolved.
FESEM images attached in below files.
Dear Adam da,
Graphene has proved challenging due to difficult bottom-up synthesis, poor solubility, and agglomeration in solution due to van der Waals interactions. The suspending in a highly-alkaline aqueous environment (high pH ) could decrease electrostatic repulsion energy overcomes van der Waals attractive forces. This might help you.
Regards
Also, you could follow the RG discussion in the link below:
https://www.researchgate.net/post/What_should_I_do_with_Nanoplatelets_graphene_agglomeration_even_after_sonication_with_different_power
Without further functionalizations,,, um so you should increase the density of the solution that may help you.
Hi All,
I did some SEM imaging, and found that the coating is not completely covering the porous substrate. Any idea on how to help with that?
I usually spin coat using dynamic dispense at 1000rpm. I tried many methods and precursor solution concentrations, but all gave the same results. See attached.
I am setting the precursor solution as 2wt.% in THF. The porous support is Anodisc, 100nm pores.
Adam da if its porous, you can run vacuum line bellow it. To make like a filtration system. Then just need to make a low concentration of graphene oxide (GO) polymer and then put the dispersion on your "original" filtration system.
The solvent will be soaked through the non covered pores arranging homogeneously your GO polymer on the surface.
good luck
Muhammad Sohail Ahmad Thank for your answer. So you mean pulling vacuum on the substrate while its spin coating? or just vacuum filtration without spin coating? Right now my porous substrate is taped to a glass slide which is spun, but I can have the substrate directly connected to vacuum
Adam da just vacuum filtration without spin coating
wishing you good luck
You can use a suitable caping agent that is the only one that can terminate the agglomeration as well as use purification processes for long as possible
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