I have a sulfonated polymer, NMP, acetone and TEA in my solution and GO was dispersed to some extent while mixing with stirrer but after ultrasonication with 300 w, in 10 minutes the whole GO coagulated and became like a gum - please advise what was the problem and how to fix it-thanks in advance
The particles aggregate. You should try to change pH. As we know nanoparticles disperse in solution by repulsive charge, which may be from carboxylic group, OH-
If the temperature of media increase to much by sonication it may aggregate polymer
Thank you Mr. Fernandes . Actually the amine groups of TEA does not allow the pH to increase which should favor GO dispersability ... I don't know about the polymer weather it incorporated in GO or not ...on the other hand i had made an ice-water bath while ultra-sonication so that temperature was not high....
maybe the polymer is incompatible with your solvent system. Is it water free? Do you need the polymer?
Yes Mr. Sobisch the polymer is necessary . it has sulfone groups and is relatively hydrophile . the whole emulsion is stable before using ultrasonic (however some of GO would precipitate while the stirring would stop..) but after using the 300 w ultrasonication. the4 coagulation of GO occurred and could be extracted from the emulsion like a gum
You can try decreasing the concentration of GO. I think as you are imparting sonication energy, graphene platelets are individualizing and surface area is increasing by a lot. thus the systme is behaving like a gel as graphene forms a dense percolating network.
it can be be due to TEA also, as high pH systems are not stable and can lead to coagulation of colloids. I hope it was helpful.
Thank you Mr.Jatin Sethi so much. do you think that TEA may affected Polymer coagulation too? (i mean the coagulated phase may have both polymer and GO?)
Mr. Lin thank you I agree I have repeated the test without GO and the same gum was formed of the polymer ....I tried both sudden and gradual addition of the two solventsbut any way it was formed
one time I left the white emulsion (containing the coagulated polymer phase) for 12 h stirring which resulted in a clear water-like solution!! the polymer was dissolved ...although a little acetone was vaporized ....
Mr. Lin thank you I agree I have repeated the test without GO and the same gum was formed of the polymer ....I tried both sudden and gradual addition of the two solventsbut any way it was formed
one time I left the white emulsion (containing the coagulated polymer phase) for 12 h stirring which resulted in a clear water-like solution!! the polymer was dissolved ...although a little acetone was vaporized ....
by the way , I have used imidazole this time instead of TEA and the amount was twice as TEA
seems that you have no emulsion - no dispersed liquid - no emulsion.
And as suggested earlier your polymer is incompatible with solvent system. Changing its composition, e.g. by evaporation may result in solution.
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