Abstract
γ-Alumina nanoparticles before and after self-assembly process. [Display omitted]
► γ-Alumina nanoparticles were prepared with average diameters of about 3–7nm. ► By using low concentration of dimethyl disulfide (DMDS), self assembly of γ-alumina nanoparticles happened at room temperature in n-hexane, forming uniform and spherical granules in the range of 1–2mm. ► Self assembly of the γ-alumina nanoparticles may be due to the selective adsorption of DMDS inside the micropores of the nanoparticles.
In this study, self assembly behavior was induced for γ-alumina nanoparticles by adsorption of dimethyl disulfide. Following this trend, we have developed a chemical process to obtain γ-alumina in the nano scale. Scanning electron microscopy images of the prepared γ-alumina showed big and strong agglomeration of the nanoparticles indicating that these nanoparticles have strong surface forces. Transmission electron microscopy images confirmed that the γ-alumina nanoparticles 3–7nm in size were converted to uniform spherical shape in the size range of 1–2mm after shaking with dimethyl disulfide in the presence of n-hexane at room temperature. This phenomenon did not appear in the case of alumina in the micro scale. The surface properties of the prepared γ-alumina in the nano scale were characterized and compared with the γ-alumina in the micro scale by using low temperature nitrogen adsorption–desorption system, indicating that the specific surface area of the prepared γ-alumina nanoparticles is larger than that of the γ-alumina in the micro scale. Furthermore, micro- and meso-pores were observed for the γ-alumina nanoparticles while only mesoporous structure was detected for the γ-alumina in the micro scale. These experimental results suggested that the self assembly behavior of the γ-alumina nanoparticles may be due to the selective adsorption of dimethyl disulfide in the micropores of these nanoparticles to act as bridge linking the nanoparticles.