A simple synthesis of size-reduce magnetite nano-crystals via aqueous to toluene phase-transfer method

A simple one-step liquid-liquid phase-transfer synthesis of magnetite nanocrystals affording enhanced size reduction is described. One-and two-step particle transfer methods are compared. In the one-step method, particles are synthesized in a biphasic medium where the particles are formed in the microdroplets and migrate to the organic phase simultaneously, whereas in the two-step method, particles are first prepared in an aqueous phase and subsequently transferred to the organic phase. In both methods, CTAB was used as both a stabilizer and a transferring agent. Data from FTIR and XRD suggest invariably that the particles obtained are of magnetite, Fe3O4. The aqueous to organic phase-transfer efficiency is > 99.5% for both methods. In the one-step method the average particle size and standard deviation (sigma) is half of that afforded in the two-step method (ca. 18.3 + 7.7 nm cf. 42.2 + 17.6 nm). This reduction in particle size is attributed to the formation of water in oil droplets that act as nanoreactors for the synthesis of magnetite particles. (C) 2007 Elsevier B.V. All rights reserved.