Repetitive heterocoagulation of oppositely charged particles for enhancement of magnetic nanoparticle loading into monodisperse silica particles

Hideki Matsumoto, Daisuke Nagao, Mikio Konno

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Oppositely charged particles were repetitively heterocoagulated to fabricate highly monodisperse magnetic silica particles with high loading of magnetic nanoparticles. Positively charged magnetic nanoparticles prepared by surface modification with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TSA) were used to heterocoagulate with silica particles under basic conditions to give rise to negative silica surface charge and prevent the oxidation of the magnetic nanoparticles. The resultant particles of silica core homogeneously coated with the magnetic nanoparticles were further coated with thin silica layer with sodium silicate in order to enhance colloidal stability and avoid desorption of the magnetic nanoparticles from the silica cores. Five repetitions of the heterocoagulation and the silica coating could increase saturation magnetization of the magnetic silica particles to 27.7 emu/g, keeping the coefficient of variation of particle sizes (CV) less than 6.5%. Highly homogeneous loading of the magnetic component was confirmed by measuring Fe-to-Si atomic ratios of individual particles with energy dispersive X-ray spectroscopy.

Original languageEnglish
Pages (from-to)4207-4211
Number of pages5
JournalLangmuir
Volume26
Issue number6
DOIs
Publication statusPublished - 2010 Mar 16

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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