A Novel Route to Toluene-Soluble Magnetic Oxide Nanoparticles: Aqueous Hydrolysis Followed by Surfactant Exchange

Ghosh, Moumita and Lawes, Gavin and Gayen, Arup and Subbanna, GN and Reiff, WM and Subramanian, MA and Ramirez, AP and Zhang, Jin-Ping and Seshadri, Ram (2004) A Novel Route to Toluene-Soluble Magnetic Oxide Nanoparticles: Aqueous Hydrolysis Followed by Surfactant Exchange. In: Chemistry of Materials, 16 (1). pp. 118-124.

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Abstract

The ability of capped nanoparticles of inorganic materials to dissolve in nonpolar solvents such as toluene creates opportunities for size-selective precipitation, surface modification through covalent means, incorporation into polymer composites, and the possibility of digestive ripening. Toluene-soluble nanoparticles are usually prepared in nonpolar solvents, where they are capped by hydrophobic surfactants; such preparations often require specialized high-temperature solvents and expensive precursors. Many transition metal oxides are easily prepared in nanoparticulate form cheaply and in quantity, by hydrolysis in aqueous media. However, capping of nanoparticles in aqueous media to make them nonpolar is usually difficult. We present here a simple process of surfactant exchange that permits $\approx4-nm$ particles of the magnetic spinel oxides $MFe_2O_4$ (M = Mn and Zn) to be prepared in water in the presence of a surfactant and to then be transferred to toluene wherein the particles are capped by a second surfactant, a long-chain amine. The aminecapped nanoparticles can be successively precipitated and redissolved from their toluene solutions. Mo¨ssbauer spectroscopy and SQUID magnetization have been used to characterize magnetic properties of the nanoparticles.

Item Type:	Journal Article
Publication:	Chemistry of Materials
Publisher:	American Chemical Society
Additional Information:	The copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Materials Research Centre Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	02 Jun 2006
Last Modified:	07 Jan 2013 06:27
URI:	http://eprints.iisc.ac.in/id/eprint/7428

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