Synthesis and Characterization of Decanoic Acid Coated Magnetic Iron (III) Oxide Nanocubes for the Preparation of Uniform Nanocube Monolayers
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While research into the synthesis and characterization of magnetic iron oxide nanospheres has been heavy, the study of different shapes of iron oxide, such as nanotubes, nanocubes, nanorods, etc. has not been thorough. In this project, we investigated the less common magnetic Fe3O4 nanocubes. These nanocubes were synthesized by the thermal decomposition of iron (III) acetylacetonate. The synthesis was carried out in the presence of decanoic acid as the surfactant and also the organic solvent dibenzyl ether. The presence of decanoic acid coated nanocubes were confirmed using Fourier Transform Infra-red (FTIR) Spectroscopy. Since iron oxide nanocubes are unstable in air and especially in solution, due to their high surface energy and tendency to aggregate, mixed solvent systems of different ratios by volume of chloroform to methanol namely, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1 were used as dispersing agents for the nanocubes with pure chloroform as a control. This was done to determine if mixed solvent systems would be able to prevent the formation of nanocube aggregates as opposed to single solvent systems. The decanoic acid coated nanocubes were analyzed under a Transmission Electron Microscope (TEM) which were deposited on carbon-coated TEM grids. These particles were deposited on the grids using two different techniques, the Langmuir-Schaefer technique at the air-water interface, as well as drop casting. Slope analysis of the isotherms obtained from Langmuir-Schaefer samples were performed to study phase transitions during sample preparation. The TEM grids for different samples were analyzed under the microscope to record images in order to study the behavior and morphology of the nanocubes. TEM analysis revealed that thin, crystalline packing of nanocubes could be achieved when the Langmuir-Schaefer technique was used with a chloroform:methanol ratio of 3:1. The size distribution of the nanocubes could be measured from TEM images and a pure chloroform sample was used to determine the average size to be 14.25 ± 4.04 nm which is quite close to the superparamagnetic limit of iron. From the results it could be confirmed that a mixed solvent system of chloroform and methanol is able to disperse decanoic acid coated nanocubes to reduce aggregation in solution and for the formation of crystalline packed layers and that thermal decomposition is a suitable method to synthesize uniform nanocubes with a narrow size distribution.