Annealing of aggregated nanoparticles (in solution)

[JeroenV]

If you have a colloid of 2 types of nanoparticles and tune the conditions (pH, salt) in such a way that one of the two particles aggregates to the surface of the other (opposite zeta potential), would it then be possible to thermally anneal this system? The end goal would be that the 2 types of nanoparticles are attached to each other and do not need opposite surface charge anymore to stay attached. Is this possible?

 

[siddharth]

I expect the nanoparticle aggregate will simply precipitate out of solution when you mix them together if you use the same solution. If you're trying to structure a multi-layer of nanoparticles though, that can be done using the Layer-by-Layer technique, if you sequentially dip a substrate into oppositely charged nanoparticle solutions so you can essentially build up layers of these particles. See this paper, for an example of how the LbL technique can be used to do this: http://pubs.acs.org/doi/abs/10.1021/la701267a

 

[JeroenV]

Thank you for your answer. By tuning the concentrations, LbL can be used without forming to big aggergates. However, my concern was if it is possible to thermally anneal the multi-layered particle after LbL. In this case they are physically attached (crystal structures are combined, however with surface defects). Then, the you can go ahead and change the pH without losing your multi-layered structure.