Polymer-Graft-Mediated Interactions between Colloidal Spheres

Research output: Contribution to journalArticle

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 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.

Details

Authors
  • Jeanette Ulama
  • Malin Zackrisson
  • Johan Bergenholtz
Organisations
External organisations
  • University of Gothenburg
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Polymer Chemistry
Original languageEnglish
Pages (from-to)2882-2890
Number of pages9
JournalLangmuir
Volume32
Issue number12
Publication statusPublished - 2016 Mar 29
Publication categoryResearch
Peer-reviewedYes