The Efficacy of Fe3O4 Nanoparticles as a Robust and Effective Alternative to Gold Nanoparticles as Photothermal Agents to Drive High-Barrier Reactions

Open Access
Author:
Johnson, Robert J
Graduate Program:
Chemistry
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
September 23, 2016
Committee Members:
  • Benjamin Lear, Dissertation Advisor
  • Benjamin James Lear, Committee Chair
  • Raymond Edward Schaak, Committee Member
  • John V Badding, Committee Member
  • James Hansell Adair, Outside Member
Keywords:
  • Magnetite Nanoparticles
  • Iron oxide nanoparticles
  • Gold nanoparticles
  • Photothermal
  • Light to heat
  • Nanoparticles
Abstract:
The photothermal effect of gold which depends on the excitation of the surface plasmon has recently become an exciting area of research. However, due to their weak bonds to their stabilizing ligands, and being a relatively soft metal leading to melting of the particles, which causes instability under photothermal conditions relevant to chemical transformations. This leads to the inability to conduct systematic studies which depend on surfactant identity or size effect. However, Fe3O4 nanoparticles have been shown to exhibit a photothermal effect and offer an attractive alternative to gold nanoparticles. Within this thesis, I show that Fe3O4 nanoparticles are able to drive the high-barrier decomposition reaction of poly(propylene carbonate), near the efficiently as gold nanoparticles. I also show that Fe3O4 nanoparticles exhibit exceptional stability, even under the most extreme photothermal conditions studied. This offers the opportunity to study how changing the size of the nanoparticle affects the photothermal efficiency. I also study the efficiency of decomposition of poly(propylene carbonate) using 5.5, 10, and 15 nm Fe3O4 nanoparticles as the photothermal agent. We then offer insight into the size dependence of the photothermal effect through the simulation of heating and cooling of the nanoparticles, ultimately determining that the heat capacity of the particle is the factor which predominantly controls the decomposition rate, and not properties such as absorption efficiency, or surface area, etc. This work ultimately offers insight into how we can better study photothermal agents other than gold to help obtain photothermal heating methods which are stable, reusable, and more sustainable than their gold counterparts.