PEG size effect and its interaction with Fe₃O₄ nanoparticles synthesized by solvothermal method: morphology and effect of pH on the stability

Author(s)

Namikuchi, Eliane A. ; Gaspar, Rafael D. L. ; da Silva, Douglas S. ; Raimundo, Ivo M., Jr. ; Mazali, Italo O.

• Document type: Journal article
• Source: NANO EXPRESS; v. 2, n. 2, p. 12-pg., 2021-06-04.

Abstract

The synthesis and characterization of Fe3O4 magnetic nanoparticles (MNPs) obtained by the solvothermal method in ethyleneglycol with the addition of polyethyleneglycol (PEG) with molar mass of 4000, 8000 and 20000 g mol(-1) are described, aimed at evaluating its effect on the size, morphology and stability of the nanoparticle. The syntheses were carried out by solubilizing the precursors at 85 and 140 degrees C, providing smaller nanoparticles as well as smaller crystallites at higher temperatures, while the effect of PEG was less evident. Measurements of nanoparticle surface areas synthesized with PEG 4000 and 20000 g mol(-1) at 140 degrees Cprovided values of 76 and 14m(2) g(-1), respectively, indicating that PEG 4000 surrounds the crystallites, while PEG 20000 preferably surrounds the whole MNP. As a consequence, MNP with very dissimilar porosities were obtained. Electron energy loss spectroscopy (EELS) indicated that MNP synthesized with PEG 20000 possesses higher electronic density than those obtained with PEG 4000, in agreement with the surface area results. Infrared spectroscopy and thermogravimetric analysis demonstrated the presence of PEG in the particles, whose amount increased as the particle size decreased. Dynamic Light Scattering (DLS) measurements showed that MNP hydrodynamic radius increases with the PEG size and stability in solution increases from pH 5.0 to 9.0 for smaller NP, while polymer presents slight effect on stability for the larger particles. The results obtained in this work show that properties of MNP can be tuned by the dissolution temperature of the chemical precursors and the PEG molar mass, changing their porosity and stability in solution, that are important variables in processes of adsorption, drug delivery and sensor developing. (AU)

• FAPESP's process: 14/50906-9 - INCT 2014: in Functional Complex Materials
• Grantee: Fernando Galembeck
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/20997-3 - Development of optical oxygen and temperature sensors based on visible and infrared emitting lanthanide ion complexes
• Grantee: Rafael Di Lazaro Gaspar
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 14/50951-4 - INCT 2014: Advanced Analytical Technologies
• Grantee: Celio Pasquini
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 13/22127-2 - Development of novel materials strategic for integrated analytical devices
• Grantee: Lauro Tatsuo Kubota
• Support Opportunities: Research Projects - Thematic Grants