Synthesizing Iron Oxide Nanostructures: The Polyethylenenemine (PEI) Role

Abstract

Controlled synthesis of anisotropic iron oxide nanoparticles is a challenge in the field of nanomaterial research that requires an extreme attention to detail. In particular, following up a previous work showcasing the synthesis of magnetite nanorods (NRs) using a two-step approach that made use of polyethylenenemine (PEI) as a capping ligand to synthesize intermediate β-FeOOH NRs, we studied the effect and influence of the capping ligand on the formation of β-FeOOH NRs. By comparing the results reported in the literature with those we obtained from syntheses performed (1) in the absence of PEI or (2) by using PEIs with different molecular weight, we showed how the choice of different PEIs determines the aspect ratio and the structural stability of the β-FeOOH NRs and how this affects the final products. For this purpose, a combination of XRD, HRTEM, and direct current superconducting quantum interference device (DC SQUID) magnetometry was used to identify the phases formed in the final products and study their morphostructural features and related magnetic behavior.

Colloidal Stability of Aqueous Suspensions of Polymer-Coated Iron Oxide Nanorods: Implications for Biomedical Applications

“…that PEI was used as a capping agent because it allows an easy control o e synthesis of homogeneous Those authors have shown that varying the length in the range between 30 and 70 nm. The PEI affinity for a specific crystal faces of akagan anisotropic growth of the crystal explaining the final rod et al 18 have shown that 25000 g/mol) does not influence the length of the akagan 38 nm. The washing step required for the complete PEI removal at the end of the synthesis is fundamental and must be done with an that is not a good solvent for PEI strong aggregation of nanorods during transformation to iron ox like morphology during transformation of akaganeite to iron oxide.…”

Synthesis of size-tuneable β-FeOOH nanoellipsoids and a study of their morphological and compositional changes by reduction

“…In contrast, FeOOH polymorphs often crystallise in the form of elongated structures even in the absence of any surfactants. [21][22][23] A two-step facile synthesis produces β-FeOOH first by simple hydrolysis and then a reduction procedure converts it to the oxide. Using the two-step synthesis, some results have shown that the morphology of the nanorods is not preserved after reduction due to the changes in the crystal structure and efforts are made towards controlling the morphology during reduction.…”

“…Using the two-step synthesis, some results have shown that the morphology of the nanorods is not preserved after reduction due to the changes in the crystal structure and efforts are made towards controlling the morphology during reduction. 23 In this article, we expand on the synthesis of β-FeOOH nanoellipsoids to provide a wider range of sizes as precursors for reduction reactions to produce anisotropic iron oxide nanoparticles.…”

Surface Compositional Change of Iron Oxide Porous Nanorods: A Route for Tuning their Magnetic Properties

“…However, we showed that the molecular weight (M W ) of PEI is a key parameter that modifies the shape of the NPs during both their synthesis and reduction. In fact, by comparing NPs obtained with and without PEI addition, we observed that the introduction of PEI determines a consistent variation in the shape and size of the resulting β-FeOOH NPs and, moreover, the use of PEI polymers with different M W also gave rise to dramatic variations in the shape and size of the final products obtained by reduction of β-FeOOH NRs [10].…”

“…Our approach to obtain mixed Mn x Fe 3−x O 4 nanorods (NRs) was developed starting from our previous results [10]. The approach consists of a multi-step strategy, described in more detail in the Materials and Methods section, which originates from the studies of Chen M. et al and Peng et al [11,12].…”