Magnetically-responsive electrophoretic silica organosols

Julian Eastoe, Gregory Smith

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

7 Citations (Scopus)
407 Downloads (Pure)



Silica nanoparticles can be dispersed in organic solvents (organosols) using surfactants, such as didodecyldimethylammonium bromide (DDAB). DDAB analogs prepared with lathanide tetrahalide counterions, either a high-magnetic moment ion (HoCl3Br, DDAH) or low-magnetic moment one (NdCl3Br, DDAN), are expected to produce charged particles, but only DDAH-stabilized dispersions are expected to be magnetically responsive.


Phase-analysis light scattering (PALS) measurements have been performed to determine the charge on DDAH- and DDAN-stabilized organosols. Magnetic sedimentation experiments have been performed to determine whether or not the silica dispersions are magnetically responsive. Sedimentation was monitored both by visual observations and UV–vis spectroscopy.


Both DDAH and DDAN organosols are negatively charged, the same as DDAB-stabilized nanoparticles. The DDAH-stabilized nanoparticles are found to respond to a magnetic field, whereas the DDAN-stabilized nanoparticles do not. This opens up possibilities for creating nanoparticle dispersions in nonpolar solvents which can be tailored to respond to desired external stimuli.

Original languageEnglish
Pages (from-to)252-255
Number of pages4
JournalJournal of Colloid and Interface Science
Early online date13 Apr 2014
Publication statusPublished - 15 Jul 2014

Bibliographical note

Short Communication


  • Electrophoresis
  • Magnetophoresis
  • Nanoparticle dispersions
  • Organosols
  • Nonpolar solvents


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