the criteria for choosing a surfactant for the dispersion of nano particles in vegetable oil?
Dear Khalid, if you want to disperse nanoparticles in vegetable oil, main question is what is the nature of the particles? Are they hydrophilic? Or hydrophobic? Anyway part of your surfactant should dissolve well in the oil AND part should want to go to the nanoparticle surface and adsorb there. I would try larger surfactants, e.g. pluronics PEO-PPO block copolymers and test a range of low HLB variants e.g. 2-7. Each oil and particle combination has a specific HLB at which stabilization can be seen.
Good luck with your work !! Kind regards, Leo
sir, what about tetronic 90R4?it has a HLB between 1-7.
what makes larger surfactants like tetronics or pluronics so suitable for vegetable oil?
Dear Khalid,
Larger surfactants have multiple sections with which they bind to the nanoparticle surface, which makes their adsorption stronger and almost irreversible allowing you to use less. Smaller surfactants attach and dis-attach and so you would need higher concentrations. With respect to Tetronic 90R4, I can say that if the amines on this surfactant have an interaction with your nanoparticles (e.g. acidic sites on the nanoparticle) than this will be the anchoring group that binds the surfactant very efficiently to the nanoparticle surface. The balance of PEO and PPO will determine whether or not the remainder of the surfactant molecule is well soluble in the oil you are using. Tetronic 90R4 has an HLB of 1-7 (meaning it is a mixture) which should be good for most oils.
Kind regards, Leo
thank you sir... one more thing is that i wanted to know about larger surfactants? Does larger surfactant means they are long chained? please answer
Dear Khalid, your welcome !!
I looked up my old notes on how to disperse particles in oils. You may want to look at slightly higher HLB surfactants as well. In my notes I see that an HLB of 7-9 is ideal for dispersing a majority of particles in vegetable oils. I would recommend looking at Pluronic P123 (available from Sigma-Aldrich) which has an HLB of 7-9.
Kind regards, Leo
Dear Khalid, is there any list in which particles are well dispersed in synthetic oil like Polyolester?
Dear Agus, the nanoparticles usually remain stable in oils after sonication for a few days (maybe a week). This is the case with most of the nanoparticles. The use of surfactants is a must for improving the stability of nanofluids.
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