Effect of Nanoparticle Surface Functionality on Magnetic and Interfacial Properties of Iron Oxide–Poly(ethylene oxide) Nanocomposites*

Magnetically susceptible nanoparticles (NPs) have shown promise in diverse application areas such as shape memory polymers, membranes, and drug delivery. In the current work, the impact of surface coating of iron oxide (Fe₃O₄) NPs on interfacial heat transfer, bulk magnetization properties, and structure of poly(ethylene oxide), PEO, nanocomposites was explored. Bare, poly(ethylene glycol) (PEG), and amine coated 10–nm–diameter Fe₃O₄ NPs were dispersed at concentrations less than 1% by weight in PEO. When exposed to an alternating magnetic field (AMF), temperature increases for all PEO/Fe₃O₄ nanocomposites. Amine and PEG coated NPs showed an improved heat generation efficiency. Analysis of magnetization curves revealed an unusual result. Amine coated NPs had the strongest magnetization, however, bare NPs showed a stronger magnetization than the PEG coated NPs. Disagreement between magnetization and magnetic heating results implies that interfacial heat transfer is impacted by NP surface modification. Simulations and experiments were carried out to identify the interfacial structure. Specific attention was paid to how the interface changes with applied AMF and how it affects the mechanism of heat transfer.