Basically I want to learn the chemistry of surfactants. By well dispersed nano particles I mean to say particles should not form secondary particles(do not agglomerate) they all should be primary particles. Furthermore, they all should be single grain domain. Particles size should be less than 20nm. Finally I want to avoid agglomerations as much as I can by precipitation method.
some words of caution and comments. Sonication does not avoid agglomeration. During every dispersing action agglomerates will break-up and form the same time. Degree of stabilization will determine which process is favoured. Zeta potential maybe helpful in case of electrostatic stabilization,but there might be surprises, especially in the nanorange.
what about your nanoparticle-is it organic or inorganic? Choosing the surfactant depends primarily upon this. Once your particle can overcome the "Zeta Potential", they shouldnt agglomerate. So, the best thing to do is first take a zeta reading of your particle and try to determine the ionic strenght, pH and surface charge and go for a suitable surfactant. But I dont complete get your question about using "precipitation method". do you want to coat your NPs with surfactant using precipitation method?
I have a doubt that can we synthesis nanoparticles with 20 nm through this method. However, one can prepare 100 - 500 nm particle size through this method. By using any silane eg. octadecyl trichloro silane one can prepare normalized size of nanoparticles. Further some exent we can succeed by using different solvent like acetone, isopropanol etc. instead of ethanol.
I want to make NPs via co-precipitation method using surfactant to minimize grain size as much as possible. Which step is most important in co-precipitation method for minimizing the grain size? i.e. PH value? surfactant? concentration? or time?
You do have to take into account all of those factors. PH value is extremely important because as you alter your pH from the point of zero charge, you will charge the surfaces of your particles, keeping them dispersed through electrostatic stabilization.
Once you add surfactant, you need to take into account whether you are using cationic, anionic, or non ionic surfactants. You will want the opposite charge of these surfactants to aid in the surrounding of the precipitated particles.
Higher concentrations of reducing agent will aid in reduction of crystallite size.
Hope this helps, or gets you started on the right road.
Article Surfactant Effects on Dispersion Characteristics of Copper-B...
The nanoparticles which was obtained from precipitation method, when you do sonication for 30 minutes, you can get well dispersed nanoparticles, Because of sonication, you can avoid agglomeration
I hope Polyvinyl pyrrolidone or CTAB surfactant would help in your way
CTAB or PVP can act as protecting agent that means it can protect the nanoparticles from agglomeration, But for well uniform dispersion nanoparticles you need to go for sonication.
some words of caution and comments. Sonication does not avoid agglomeration. During every dispersing action agglomerates will break-up and form the same time. Degree of stabilization will determine which process is favoured. Zeta potential maybe helpful in case of electrostatic stabilization,but there might be surprises, especially in the nanorange.
I agree with Titus! Sonication is not a whole solution for avoiding agglomeration. You need to play around with the concentration of the anionic or cationic surfactant, the pH change after adding the surfactant, ionic strength etc. Keep one parameter as constant and try changing the other while taking Zeta for each change. When you compare all the graphs, you would come to know what is the most important parameter and what range it should be.
Sonication in presence of surfactant can be used. If the precipitate is done alongwith the surfactant then you get soft agglomerate, which can be broken easily to nano level.
Depends on factors like sonication type weather probe or bath sonicator, sonication time, type of surfactant, pH value etc... you can try adding surfactant PVP for before a day to base fluid and wait fr a day then by adding nano particles you can try...
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nanostructured Materials
- Nanoparticles