Mesoporous silica/nanoparticle composites prepared by 3-D replication of highly filled block copolymer templates

Abstract

The incorporation of iron platinum (FePt) nanoparticles (NPs) within the walls of mesoporous silica was achieved at high NP loadings using highly filled amphiphilic poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (Pluronic®) copolymer templates prepared by exploiting selective hydrogen bonding between the pre-synthesized nanoparticles and the hydrophilic portion of the block copolymer. The mesoporous silica/NP composites were then synthesized by means of phase selective condensation of tetraethylorthosilicate (TEOS) within the NP loaded block copolymer templates dilated with supercritical carbon dioxide (scCO₂) followed by calcination. The resulting mesoporous silica composites were prepared at nanoparticle loadings as high as 25 wt% relative to the template (15 wt% relative to mesoporous silica) and were characterized by electron microscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The method described in this report is general and may be applied to a variety of NPs for encapsulation within the pore walls of mesoporous silica.