pH and Salt Response of Mixed Brushes Made of Oppositely Charged Polyelectrolytes Studied by in Situ AFM Force Measurements and Imaging
| Autor: | Astrid Drechsler, Manfred Stamm, Petra Uhlmann, Mahdy M. Elmahdy |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
chemistry.chemical_classification
Materials science 010405 organic chemistry Salt (chemistry) Surfaces and Interfaces 010402 general chemistry Condensed Matter Physics 01 natural sciences Polyelectrolyte 0104 chemical sciences Colloid chemistry.chemical_compound chemistry Chemical engineering Pyridine Electrochemistry medicine General Materials Science Swelling medicine.symptom Layer (electronics) Softening Spectroscopy Acrylic acid |
| Zdroj: | Langmuir. 34:4739-4749 |
| ISSN: | 1520-5827 0743-7463 |
| DOI: | 10.1021/acs.langmuir.8b00498 |
| Popis: | The response of mixed brushes made of poly(acrylic acid) and poly(2-vinyl pyridine) with a mixing ratio of about 60:40 was studied using atomic force microscopy (AFM) force measurements with colloidal probes and AFM imaging with a sharp tip in the pH range between 2.5 and 8 and at varying KCl concentrations up to 1 M. It was found that under all conditions a dense polyelectrolyte complex layer coexists with excess polyelectrolyte chains in varying swelling states depending on pH and salt concentration. The mixed brush thus combines typical features of polyelectrolyte brushes and complexes. So, the increase of the salt concentration not only led to a transition from osmotic to salted brush regime but also to salt-induced softening or partial decomposition of the complex layer. Attractive forces at high salt concentrations indicated the presence of P2VP chains in the swollen layer even at high pH values. |
| Databáze: | OpenAIRE |
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