Polymer-Graft-Mediated Interactions between Colloidal Spheres
| Autor: | Johan Bergenholtz, Malin Zackrisson Oskolkova, Jeanette Ulama |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
chemistry.chemical_classification
Chromatography Materials science 02 engineering and technology Surfaces and Interfaces Polymer 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences 0104 chemical sciences Solvent chemistry.chemical_compound Colloid Chemical engineering chemistry Virial coefficient Excluded volume Electrochemistry Particle General Materials Science 0210 nano-technology Dispersion (chemistry) Ethylene glycol Spectroscopy |
| Zdroj: | Langmuir. 32:2882-2890 |
| ISSN: | 1520-5827 0743-7463 |
| Popis: | Aqueous dispersions of fluorinated colloidal spheres bearing grafted poly(ethylene glycol) (PEG) are studied as a function of salt and particle concentration with the aim of improving the understanding of interactions among polymer-grafted particles. These dispersions can sustain large concentrations of salt, but crystals nucleate in dilute dispersions when a sufficient Na2CO3 concentration is reached, which is attributed to the presence of attractions between particles. On further increasing the Na2CO3 concentration, the solvent is rapidly cleared of particles. Small-angle X-ray scattering and cryogenic transmission electron microscopy are employed in order to quantify the attractions. The former is used to extract a second virial coefficient, and the latter shows that the PEG-graft contracts as a function of increasing salt concentration. The contraction not only leads to a reduction in excluded volume but also is accompanied by attractions of moderate magnitude. In contrast, dispersion of the particles in ethanol, in which bulk PEG solutions crystallize, lead to fractal structures caused by strong attractions. |
| Databáze: | OpenAIRE |
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