Scientists from Netherlands have recently reported on the formation of silver containing composite nanoparticles (CNPs) consisting of silver nanoparticles (Ag-NPs), poly(N-methyl-2-vinyl pyridinium iodide)-block-poly(ethylene oxide), P2MVP38-b-PEO211 and poly(acrylic acid)-block-poly(isopropyl acrylamide), PAA55-b-PNIPAAm88. Both the Ag-NPs and the CNPs from spontaneously upon mixing of the double hydrophilic block copolymers in the presence of silver ions; that is, without the addition of a reducing agent such as NaBH4. Paper demonstrate the possibilities to achieve control over the size of the Ag-NPs, the size and shape of the CNPs, and the location of the Ag-NPs within the CNPs. Ag-NPs were found to colocalise with the polyelectrolyte blocks within the CNPs. Temperature could be used to trigger a structural transition from a core–shell structure at T = 25 °C to a core–shell–corona structure at T = 60 °C , translocating the Ag-NPs from the micellar core in the former into the micellar shell in the latter. The most uniform and well-defined CNPs were obtained by premixing Ag+ and P2MVP38-b-PEO211 at room temperature prior to addition of this solution to a solution of PAA55-b-PNIPAAm88 at T = 25 °C (sample H). It has been shown that the colloidal stability of the CNPs is dependent on the ionic strength of the solution: Ag-NP release from the CNPs can easily be triggered by addition of a simple salt, such as NaNO3.
This work summarizes that complex coacervate core micelles can be regarded as a promising candidate for polymer-assisted synthesis and stabilisation of silver nanoparticles. Future work might be directed towards the potential application of such CNPs as environment-sensitive silver quantum dots and as antimicrobial agents in antifouling surface coatings that can be prepared upon exposure of hydrophilic surfaces to a solution of Ag-NP containing CNPs.
paper can be found at Journal of colloid and Interface Science, Vol 339, 2, pp 317-324
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