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Polymer-Graft-Mediated Interactions between Colloidal Spheres

Ulama, Jeanette; Zackrisson, Malin LU and Bergenholtz, Johan LU (2016) In Langmuir 32(12). p.2882-2890
Abstract

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... (More)

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.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Langmuir
volume
32
issue
12
pages
9 pages
publisher
The American Chemical Society
external identifiers
  • Scopus:84962415094
ISSN
0743-7463
DOI
10.1021/acs.langmuir.5b04739
language
English
LU publication?
yes
id
a009437b-df04-4799-96cf-f6689a838ca5
date added to LUP
2016-06-29 11:48:01
date last changed
2016-09-20 03:12:35
@misc{a009437b-df04-4799-96cf-f6689a838ca5,
  abstract     = {<p>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 Na<sub>2</sub>CO<sub>3</sub> concentration is reached, which is attributed to the presence of attractions between particles. On further increasing the Na<sub>2</sub>CO<sub>3</sub> 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.</p>},
  author       = {Ulama, Jeanette and Zackrisson, Malin and Bergenholtz, Johan},
  issn         = {0743-7463},
  language     = {eng},
  month        = {03},
  number       = {12},
  pages        = {2882--2890},
  publisher    = {ARRAY(0xad99298)},
  series       = {Langmuir},
  title        = {Polymer-Graft-Mediated Interactions between Colloidal Spheres},
  url          = {http://dx.doi.org/10.1021/acs.langmuir.5b04739},
  volume       = {32},
  year         = {2016},
}