Polymer-hematite nanocomposites: templating effect of commercial ion-exchangers in the growth of size-controlled iron oxide nanoparticles.

: The commercially available ion-exchange resin Amberlite IR120 has been used as the stabilizing agent for the preparation of a size controlled nanostructured hematite phase. The employed synthetic approach, based on the loading of Fe3+ by ion exchange and the subsequent treatment with an aqueous base solution, produces a nanocomposite material with a remarkably high content of oxide nanoparticles (iron content = 18.8% w/w, corresponding to 24.9% w/w of Fe2O3). Scanning electron microscopy and energy dispersive X-ray spectroscopy investigation show that the iron distribution is egg-like and parallels the distribution of the sulfonic groups of the ion-exchanger. Transmission electron microscopy characterization reveals that the size of the ferric oxide nanoparticles in the nanocomposites is narrowly distributed in the 4-6 nm range and that it is the same after the first and the fifth ion-exchange-precipitation cycle. Selected area Electron Diffraction (SAED) analysis of the nanostructured oxide after five ion-exchange-precipitation cycles indicates that it is hematite with a distorted structure.