Preparation of Hollow Ormosil Particles Containing Copper Nanoparticles

초록

Monodisperse hollow ORMOSIL particles were produced by two-step (acid-base) process in an aqueous solution with phenyltrimethoxysilane (PTMS). Particle size and hollow size can be controlled by changing monomer concentration, hydrolysis time and reaction temperature. Compared to emulsion/phase separation technique, the two-step method produces hollow particles without a template, including advantages such as high purity, high solid content, and easy process. Using the hollow ORMOSIL particles in size of ca. 400 nm, Cu-containing particles were prepared by chemical reduction in an alcoholic solution. The hollow particles were dispersed to an alcoholic solution containing Cu(II) salt, and then a reducing agent was added to the solution. The mixture solution was stirred for 2 h in refluxing condition. The Cu-containing ORMOSIL particles were obtained through centrifugation and filtration. To find out optimum condition for the preparation of the particles, the reaction was performed with the variation of the anion of Cu(II) salt, reducing agent, solvent, and so on. The size of copper in resultant particles was in the range of 40-50 nm, and increased to ca. 250 nm by repeating reduction procedure. In addition, using the resultant Cu-containing particles, Ag-containing ORMOSIL particles were also obtained by spontaneous redox reaction due to the difference of reduction potential. The composition and crystallinity of metal particles in the resultant particles were determined by X-ray diffractometer (XRD). The size and morphology of the particles were observed with field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). And the resultant particles were also characterized by thermogravimetric analysis (TGA).