I would like to disperse a PEKK powder in an aqueous media. I must use a surfactant to impede agglomeration and sedimentation and to lower viscosity. Is anyone have a suggestion about the surfactant I should use?
Thanks a lot for any contribution!
Marc Singlard
I like the name of your institute after the famous author.
Any surfactant that works can be used... This is not a facetious remark... A surfactant is simply a wetting agent, so you could actually start by mixing the polymer (powder, I assume) with neat washing-up liquid. Then try diluting the system without the polymer phase coming out. Issues may only arise when (for example) you're trying to measure the particle size distribution with laser diffraction and foaming becomes an issue. In sample preparation terms then we'd normally prefer a non-ionic surfactant (e.g. Nonidet P40/P42) to begin with as this doesn't affect the charge distribution in the system.
Impeding agglomeration comes from either charge (electrostatic) or steric stabilization and that implies an anionic surfactant for the former as cationic surfactants are not common. Triton X-100 is a good reliable surfactant but much more expensive than washing up liquid. Take a look at (registration required) for more philosophy:
Dispersion and nanotechnology
https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W190528DispNanoMat
Dear Marc,
I never worked before with PEKK. If the suggestion of Alan Rawle (neat washing-up liquid) solve your problem, it is the simpler and cheaper way. But I would suggest you to try, besides common surfactants available in your lab, any dispersing additive employed in cement industry. Examples: Master Glenium (BASF), Optima 100 (CHRYSO), etc. First things always first: if the additive intended is not soluble in water, forget it. Good luck.
Regards, Antonio
Marc Singlard
The only (strictly/formally) dispersing agent is energy. Surfactants are wetting agents and admixtures (e.g. phosphate) are stabilization agents in the sequence wetting, separation (the key step), stabilization (preventing recombination of separated particles) in making a stable dispersion. A charged surfactant in the correct concentration may combine both wetting and stabilization. View the webinar above.
Alan F Rawle
Thank you for your response. I will take a look at the webinar you suggested.
Did you recommend to make a mixture with the PEKK powder and surfactant before diluting in water? In a first approach, I would have diluted the surfactant in water and then added the powder while stirring.
Antonio Bombard
Master Glenium and Optima 100 are marked as plasticizer on technical data sheet, with no reference to chemical formula. Are there really surfactant products?
Hi Marc. Master Glenium, there are several different "types" with different #. Try Glenium 51. But all are based in polycarboxylate ethers. Don't worry about the word "plasticizer". It is a rheological term, very appropriated for cement paste. Optima 100 was developed as a phosphonate polyether. Also sold cement industry. However, recently, researchers from Nice University tested it with success for dispersions in water, not cement particles. So... I can not warranty if they will work with your powder. Good luck.
Marc Singlard
For highly hydrophobic materials such as PTFE, I've mixed with neat surfactant to wet the surface before dilution - diluted surfactants do not work in such regimes. Normal surfactant concentrations for wetting are in the 0.5 - 5wt% range and, in many instances, one can do as you suggest - attempting wetting in a 1% Triton X-100 regime, for example. This is always advisable when cost is important as the surfactant is usually the most expensive in any mixture. Using the least amount of surfactant that allows wetting is always desirable. However, nothing is a substitute for some easy experimentation (vial tests) - hence my suggestion of neat washing up liquid. Has been almost universally successful.
Antonio Bombard
Thank you for your explanations. Do you have a reference or or a name about the work you mentionned from Nice University?
Alan F Rawle
I understand that I will be difficult to wet hydrophobic particles in water even with surfactant (due to agglomeration and poor wettability I assume). However, how can I achieve an homogeneous mix of powder and surfactant whitout solvent? It seems really unlikely that surfactant molecules coat all the particles with a concentration about 1 %. Maybe I missed something
Here is, Marc (mon grand père il nee a Bordeaux, 189..?) They were gipsies, who immigrate to Brazil.
Bossis, G, Grasselli, Y, Meunier, A, et al. (2016) Outstanding magnetorheological effect based on discontinuous shear thickening in the presence of a superplastifier molecule. Applied Physics Letters 109(11): 111902.
Marc Singlard
One good experiment is worth a thousand debates or Greek letters... I think you're over-thinking this...
You state 'it seems really unlikely that surfactant molecules coat all the particles with a concentration about 1 %'. Exactly my point - try the neat surfactant mixed with the powder to wet. On dilution, if the polymer phase comes out of suspension, then you've diluted too much.
Otherwise move to dry analysis or to dilution in a liquid such as propan-2-ol...
Antonio Bombard
Thank you for the article; it is very interestingin a first approach. I was not aware about the phosphonate surfactants.
It's a small world!
Alan F Rawle
Thank you for your advises, i I will first try the method you have described with the neat washing surfactant. You helped me a lot!
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