Is there a method for transferring dispersed primary(~20nm) silica nanoparticles (NP) from ethanol to water without significant aggregation? If you happen to know a dispersed silica synthesis/coating method using water as the main solvent, I would be interested in learning about it. I want to study how its practical applications performance differs when suspended in the more economic option of water.
I know silica like to aggregate/agglomerate upon calcination and their dispersability is reduced as well. Water also has a weaker zeta potential than ethanol as a solvent for silica. The silica NP I'm using are synthesized using variations of the Stober method, ideally sub 100nm in size, and are suspended in organic solvents such as ethanol and methanol for good dispersion between the 10~1000 nm nanoparticles.
I want to analyze the size dispersion with a Particle Size analyzer as well as with Dynamic Light scattering so the solvent is important.
Please explain 'Water has a weaker zeta potential than ethanol as a solvent for silica'....
Dear Brandon,
We have recently developed a technique for NP transfer without the formation of aggregates using surfaces covered with PNIPAM polymer brushes. The NPs adhere to the PNIPAM surfaces in a 30-70 vol.% ethanol-water mixture, while they can be released in the pure solvents. We explain the method in more detail in Y. Yu et al., Nanoscale 9, 1670-1675 (2017). I hope this will help you forward.
Best wishes,
Sissi
http://pubs.rsc.org/en/Content/ArticleLanding/2017/NR/C6NR09245D#!divAbstract
Article Pick up, Move and Release of Nanoparticles Utilizing Co-non-...
there are several commercial products of narrowly distributed silica particles in water, e.g. Köstrosol, Lutensol. Colloidal stability in demineralized water is not a problem, even at isoelectric point around pH 2. At higher pH when negatively charged electrolyte addition causes agglomeration. Transfer to deionized water should not be a problem.
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