Colloidal polymers via dipolar assembly of magnetic nanoparticle monomers

Lawrence J. Hill, Jeffrey Pyun

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


In this Spotlight on Applications, we describe our recent progress in the preparation of hierarchical one-dimensional (1-D) materials constructed from polymer-coated ferromagnetic cobalt nanoparticles. We begin with a general discussion of nanoparticles capable of 1-D self-organization to form 1-D assemblies, which we term colloidal polymers. The need for efficient, highly directional interactions prompted our investigation with polymer-coated ferromagnetic nanoparticles, which spontaneously form linear assemblies through coupling of north and south magnetic poles present in these single-domain ferromagnetic nanoparticles. These highly directional N-S interactions and the resulting formation of 1-D assemblies can be understood in the context of traditional polymer-forming reactions. The dipolar assembly of these ferromagnetic nanoparticles into chains and binary assemblies while dispersed in organic media has been investigated as a key foundation to form novel magnetic materials and heterostructured nanocomposites. These studies enabled the fabrication of magnetic nanoactuating systems resembling "artificial cilia and flagella". We then discuss our recent efforts to prepare cobalt oxide nanowires using various nanoparticle conversion reactions through a process termed colloidal polymerization. A series of novel functional "colloidal monomers" based on dipolar cobalt nanoparticles were also prepared, incorporating noble metal or semiconductor nanoinclusions to form heterostructured cobalt oxide nanocomposites.

Original languageEnglish (US)
Pages (from-to)6022-6032
Number of pages11
JournalACS Applied Materials and Interfaces
Issue number9
StatePublished - May 14 2014


  • cobalt nanoparticles
  • cobalt oxide nanowires
  • colloidal polymerization
  • colloidal polymers
  • dipolar assembly
  • magnetic nanoparticles

ASJC Scopus subject areas

  • Materials Science(all)


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