I want to disperse the nanoparticles because I need to coat the TEOS on the surface to prevent aggregation.
Today I try to use probe sonicator to disperse the sample which contents 0.1g nanoparticles in 12ml diwater for 5min.
But it is easy to aggregate after 1-2min
Maybe sonicate more time or add surfactant?
In previous papers, many people say that it hard to redisperse the nanoparticle after drying. So I do not know if I will do it will be successful
It will be very hard to redisperse the particles if they were dried.
Dear Yen-Ching,
1.I believe your Iron oxide nanoparticles are at their isoelectric point under this condition. At isoelectric point, the iron oxide nanoparticles having *ZERO* surface charge. So, there will be no electrostatic repulsion to prevent the particles from re-agglomerate. Note that agglomeration of iron oxide nanoparticles is favorable due to van der Waals and magnetic dipole-dipole attraction.
2. My suggestion is, sonicate the particles for 15 minutes, adjust pH of the suspension to pH 3- pH 4. Then, sonicate again the particles for another 15 minutes and you will get a much stable suspension. At pH 3- pH 4, the particles gained net positive charge and thus develop high electrostatic repulsion among themselves.
3. Nevertheless, based on my experience, most commercial nanopowder unable to be redispersed back into their primary particle size. This phenomenon mostly due to the presence of sintered aggregates in the particles which formed during the drying process.
4. Hence, even you manage to disperse the powder into suspension form, the particles would have appeared as polydisperse agglomerates. I expect the presence of polydisperse agglomerates will, later on, affect the final size of your TEOS-coated particles.
5. Thus, I strongly suggest you begin with own made iron oxide nanoparticle suspension. There are numerous methods available in literature talking on the synthesis of stable yet monodisperse iron oxide nanoparticles.
Best Regards
Thank you for your reply, I have discussed with my professor.decided to own synthesis, because the final consideration of the size of the problem
I decided to synthesis the nanopaticles, because the particle size will become the big problem.
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nanoparticle Research