Colloids and Gels Containing Magnetic Nanoparticles

• Author / Creator

  Zheng, Lelin

• Magnetic nanoparticles (MNPs), whose positions and motions can be controlled by external magnetic fields, have been widely used and designed into applications both in academia and industries especially when dispersed in media such as colloids and hydrogels, owing to the combination of their unique properties and the advantages of the media. These applications include drug delivery, contamination treatment, photonic crystal e-paper, and soft actuators. In recent years, there has been rapid advances in these fields.
  This thesis summarizes two projects. In the first project, a colorimetric voltmeter has been fabricated using magnetic Fe3O4@SiO2 nanoparticles in colloids for the application as an overpotential alarm system in zinc-air batteries. These colloidal nanoparticles self-assemble into an amorphous photonic crystal whose interparticle distance varies under electric field, leading to a colorimetric display of the applied field. By connecting the two electrodes of zinc-air battery to each end of a capacitor filled with the two colloidal nanoparticles between transparent electrodes, I have achieved a simple and intuitive way to monitor the status of rechargeable batteries. Specifically, the performance of zinc-air battery, including discharging, charging, overcharging and aging behaviors have been monitored by the colour display of the capacitor device. In general, the application of colloidal MNPs as a battery monitoring device are proposed and discussed.
  In the second project, I have reviewed the recent progress in the field of magnetic hydrogels, especially in soft robotics applications. Firstly, the strategies for dispersing the MNPs in the hydrogels are discussed with examples from the literature. Secondly, the three major fields of current applications, including drug delivery, enzyme immobilization and separation of cell and protein, as well as microorganisms and organics detection and purification of wastewater are reviewed. Thirdly, the operation principles and application of magnetic hydrogels in the upcoming field of soft robotics are demonstrated with examples.
  Overall, this thesis describes various aspects of MNP study, ranging from synthesis to applications in colloidal suspension and in hydrogel media. I harnessed amorphous photonic crystal property of colloidal MNP to fabricate a colorimetric voltmeter that monitors the overcharging status of zinc-air battery. I reviewed the dispersion and application of MNPs in hydrogels, with an emphasis on the applications in soft robotics systems. I anticipate that my work can inspire novel application-driven researches on MNP based materials. Specifically, I envision applications of MNP based colloids and gels in soft devices such as battery indicators, biomimicking artificial muscles and sensory artificial skins.

• Subjects / Keywords

  • Fe3O4 nanoparticles
  • colloids
  • magnetic nanoparticles
  • amorphous photonic crystals
  • magnetic hydrogels

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-yqgf-bf10

• License

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