Poly(N-isopropylacrylamide) Response to Salt Concentration and Anion Identity: A Brush-on-Brush Study
| Autor: | Grant B. Webber, Edwin C. Johnson, Ben A. Humphreys, Erica J. Wanless |
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| Rok vydání: | 2019 |
| Předmět: |
Aqueous solution
Chemistry Colloidal silica 02 engineering and technology Surfaces and Interfaces Electrolyte 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences 0104 chemical sciences symbols.namesake chemistry.chemical_compound Colloid Ion binding Dynamic light scattering Chemical engineering Electrochemistry symbols Poly(N-isopropylacrylamide) General Materials Science 0210 nano-technology Spectroscopy Debye length |
| Zdroj: | Langmuir. 35:10818-10830 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/acs.langmuir.9b00695 |
| Popis: | The stability of poly(N-isopropylacrylamide) (PNIPAM) brush-modified colloidal silica particles was compared to asymmetric and symmetric PNIPAM brush direct force measurements in the presence of 1, 10, and 500 mM aqueous salt solution of KCl, KNO3, and KSCN between 10 and 45 °C. Dynamic light scattering measurements highlighted subtle variations in the salt-mediated thermoresponse, while atomic force microscopy (AFM) force curves between a bare silica or PNIPAM brush-modified colloid probe and a planar PNIPAM brush elucidated differences in brush interactions. The AFM force curves in the presence of KCl primarily revealed steric interactions between the surfaces, while KNO3 and KSCN solutions exhibited electrosteric interactions on approach as a function of the chaotropic nature of the ion and the solution concentration. The symmetric PNIPAM brush interaction highlighted significant variations between KCl and KSCN at 1 and 500 mM concentrations, while the approach and retraction force curves were relatively similar at 10 mM concentration. The combination of these techniques enabled the stability of PNIPAM brush-modified colloidal dispersions in the presence of electrolyte to be better understood with specific ion binding and the solution Debye length playing a significant role. |
| Databáze: | OpenAIRE |
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