Electrolyte-induced Instability of Colloidal Dispersions in Nonpolar Solvents

Gregory Smith, Samuel Finlayson, Sarah Rogers, Paul Bartlett, Julian Eastoe

Research output: Contribution to journalArticle (Academic Journal)peer-review

8 Citations (Scopus)
314 Downloads (Pure)

Abstract

Dispersions of poly(methyl methacrylate) (PMMA) latexes were prepared in a low dielectric, nonpolar solvent (dodecane) both with and without the oil-soluble electrolyte, tetradodecylammonium-tetrakis(3,5-bis(trifluoromethyl)phenyl)borate. For dispersions with a high concentration of background electrolyte, the latexes become colloidally unstable and sediment in a short period of time (<1 h). This is completely reversible upon dilution. Instability of the dispersions is due to an apparent attraction between the colloids, directly observed using optical tweezers by bringing optically trapped particles into close proximity. Simple explanations generally used by colloid scientists to explain loss of stability (charge screening or stabilizer collapse) are insufficient to explain this observation. This unexpected interaction seems, therefore, to be a consequence of the materials that can be dispersed in low dielectric media and is expected to have ramifications for studying colloids in such solvents.
Original languageEnglish
Pages (from-to)4668-4672
Number of pages5
JournalJournal of Physical Chemistry Letters
Volume8
Issue number19
Early online date30 Aug 2017
DOIs
Publication statusPublished - 5 Oct 2017

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