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Shaping the Assembly of Superparamagnetic Nanoparticles.

Minghan HuHans-Juergen ButtKatharina LandfesterMarkus B BannwarthSanghyuk WoohHéloïse Thérien-Aubin
Published in: ACS nano (2019)
Superparamagnetism exists only in nanocrystals, and to endow micro/macro-materials with superparamagnetism, superparamagnetic nanoparticles have to be assembled into complex materials. Most techniques currently used to produce such assemblies are inefficient in terms of time and material. Herein, we used evaporation-guided assembly to produce superparamagnetic supraparticles by drying ferrofluid droplets on a superamphiphobic substrate in the presence of an external magnetic field. By tuning the concentration of ferrofluid droplets and controlling the magnetic field, barrel-like, cone-like, and two-tower-like supraparticles were obtained. These assembled supraparticles preserved the superparamagnetism of the original nanoparticles. Moreover, other colloids can easily be integrated into the ferrofluid suspension to produce, by co-assembly, anisotropic binary supraparticles with additional functions. Additionally, the magnetic and anisotropic nature of the resulting supraparticles was harnessed to prepare magnetically actuable microswimmers.
Keyphrases
  • iron oxide nanoparticles
  • iron oxide
  • walled carbon nanotubes
  • ionic liquid
  • molecularly imprinted
  • high resolution