I prepared magnetite nanoparticles coated with APTES and was wondering what the best long term storage conditions to maintain stability and reduce oxidation?
Alan F Rawle They are in DI water. But they were in dried form before I coated with APTES...
Article Impact of Storage Conditions and Storage Time on Silver Nano...
Some references to help you
Article Impact of Storage Conditions and Storage Time on Silver Nano...
Rami Barakat
Sorry for the delay in getting back to you. Work got in the way.
The long range magnetic forces in magnetite will always overcome any electrostatic (charge) stabilization mechanisms, so aggregation is a given unless steric stabilization mechanisms are employed. Your system has been exposed to air and moisture (water) so I think now it's unlikely you'll be able to do anything. The danger is oxidation of the Fe2+ in Fe3O4 (Nominally FeO + Fe2O3) to Fe3+ (i.e. a rusting mechanism). I don't think that your later addition of silane will prevent this (water and oxygen may still be able to diffuse through this barrier). Ideally you'd make the material in a dry inert atmosphere and store under vacuo with a drying agent. Alternatively making and retaining the material in colloidal suspension with steric protection (e.g. PEG or PEI) is an alternative stabilization mechanism.
Magnetite has a high density (~ 5.5 g/cm3) and thus will sink rapidly in water if not truly nano (< 100 nm). This will be a good test of the 'nanoness' of your material. Carry out a Stokes' Law calculation as per ASTM E2490-09 (15) Table 1.
Let us know how you get on.
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