Interactions between silica particles and poly(2-vinylpyridine) brushes in aqueous solutions of monovalent and multivalent salts
| Autor: | Petra Uhlmann, Manfred Stamm, Mahdy M. Elmahdy, Astrid Drechsler, Eva Bittrich |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
chemistry.chemical_classification
2-Vinylpyridine Valence (chemistry) Aqueous solution Polymers and Plastics Analytical chemistry Ion Colloidal probe technique chemistry.chemical_compound Colloid and Surface Chemistry chemistry Ellipsometry Pyridine Materials Chemistry Physical and Theoretical Chemistry Counterion |
| Zdroj: | Colloid and Polymer Science. 292:1999-2012 |
| ISSN: | 1435-1536 0303-402X |
| DOI: | 10.1007/s00396-014-3291-z |
| Popis: | AFM colloidal probe technique, scratch tests, and spectroscopic ellipsometry are employed to study the conformation of a poly(2-vinyl pyridine) brush grafted to a planar surface and its interaction with microsized silica spheres in solutions containing monovalent (Cl−) and multivalent counterions (SO4 2− and PO4 3−) at pH 2.5. During approach of the sphere, steric repulsion is observed with all salts at any concentration. The approach force-distance curves are fitted according to the Alexander-de Gennes model in order to calculate the equilibrium brush thickness L. These data are compared to the brush thickness determined by ellipsometry and AFM scratch tests. Different values are obtained but all of them decrease with increasing salt concentration. This effect is enhanced by counterions of higher valence because they have a stronger screening effect and ion correlation due to their greater charge per unit volume. With NaCl solutions, a reswelling of diluted P2VP coils is observed at Cl− concentrations >1 M. When the sphere is retracted, weak adhesion forces occur at Cl− concentrations >1.3 × 10−2 M and at all concentrations of SO4 2− and PO4 3−. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full text from SpringerLink