Salt-Induced Aggregation of Negatively Charged Gold Nanoparticles Confined in a Polymer Brush Matrix
| Autor: | Regine von Klitzing, Tim Moeller, Jan Genzer, Stephanie Christau, Ralf Koehler |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
chemistry.chemical_classification
Aqueous solution Polymers and Plastics Organic Chemistry Surface plasmon Nanoparticle Salt (chemistry) 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Polymer brush 01 natural sciences 0104 chemical sciences Ion Inorganic Chemistry Chemical engineering chemistry Colloidal gold Polymer chemistry Materials Chemistry 0210 nano-technology Plasmon |
| Zdroj: | Macromolecules. 50:7333-7343 |
| ISSN: | 1520-5835 0024-9297 |
| Popis: | We report on the salt-induced aggregation of citrate-coated gold nanoparticles (AuNPs) confined within poly(N-isopropylacrylamide) (PNIPAM) brushes grafted from flat substrates. Compared to highly dispersed AuNPs, a red-shift and broadening of the surface plasmon (SP) band is observed when the AuNPs are confined by the PNIPAM brush matrix due to their close vicinity. Additional red-shifting and broadening occur upon immersion in aqueous salt solutions (1 M NaF, NaCl, NaBr, and KCl). Nanoparticle assemblies are established due to salt-induced aggregation of AuNPs and are dependent on the type of salt. In the presence of KCl, nanoparticle assemblies are built up that result in the formation a second plasmon peak at ∼700 nm. The color change of PNIPAM/AuNP is associated with (1) the collapse of the PNIPAM brushes in the presence of salt and (2) nanoparticle aggregation due to electrostatic screening of the negative charges around the AuNPs by the salt ions. Ion specificity is related to ion-pair association ... |
| Databáze: | OpenAIRE |
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