engleski

γ-Irradiation Synthesis and Characterization of Iron Oxide Nanomaterials

γ-irradiation is an attractive and ecologically friendly technique for the synthesis of magnetic nanoparticles (MNPs) at room temperature. It has the advantage of inducing electrons and other reducing species homogeneously throughout the reaction vessel. Unlike radiolytic synthesis of noble metal NPs, the radiolytic synthesis of iron oxide NPs is much less investigated. One of the reasons is a very complex iron oxide chemistry that produces numerous phases. Furthermore, MNPs have a high tendency for agglomeration and due to these reasons, various polymers are used that act as dispersants and stabilizers of MNPs in suspensions as well as growth and surface modifiers. We investigated the effect of 3 different polymers (DEAE- dextran, dextran sulfate and poly(ethylene oxide)), as well as the effect of absorbed dose of γ-irradiation on the synthesis of iron oxide MNPs. The results have shown that dextran polymers, especially DEAE-dextran, completely stabilize the precursor particles forming colloidal precursor solutions before irradiation. Irradiation of such colloidal solutions resulted in the synthesis of stable magnetic suspensions. In the case of DEAEdextran, the phase composition of formed NPs was predominantly magnetite or δ- FeOOH depending on the absorbed dose [1]. In the case of dextran sulfate, a multiphasic system was obtained in all cases [2]. On the other hand, on irradiation in the presence of PEO a completely different kind of product forms - PEO/Fe-oxide magnetic nanocomposite hydrogel. Due to the nature of the PEO polymer, a simultaneous crosslinking of the polymer and reduction of precursor NPs to single-phase iron oxide nanoparticles (magnetite in most cases) occurred. Mössbauer spectroscopy was used to investigate the hyperfine interactions of the materials. Samples generally exhibited superparamagnetic relaxation phenomena, and in some cases, samples were not completely magnetically blocked even at 77 K (Fig. 1). Acknowledgments: This work has been supported by the Croatian Science Foundation under the project UIP-2017-05-7337 (POLRADNANOP). References: [1] I. Marić, G. Drazić, G. Štefanić, K. Zadro, M. Gotić, T. Jurkin, Materials Characterization, Vol. 159, 110038 (2020) [2] I. Marić, G. Štefanić, M. Gotić, T. Jurkin, Journal of Molecular Structure, Vol. 1183, p. 126 (2019)

gamma-irradiation ; amino dextran ; dextran sulfate ; poly(ethylene oxide) ; feroxyhyte ; magnetite ; Mössbauer spectrometry ; magnetic measurements

nije evidentirano