Innovative Silica Acorn Core–Shell Nanostructures: Morphological Control and Applications in Chromatography

This study introduces the synthesis and characterization of advanced silica core–shell nanostructures, with an emphasis on the innovative Si-ACS (Silica Acorn Core–Shell) design and its modified counterparts. Employing the classic Stöber method, SiCore particles were first produced, followed by the creation of the acorn-like Si-ACS structures. A key aspect of this research is the exploration of the effects of CTAB and TEOS concentrations on the morphology and properties of the silica shells. The study reveals that surfactant concentration influences shell morphology from corn-like to uniformly thin structures, as well as the shell thickness. Specifically, increasing the CTAB concentration from 45.8 mM to 166.9 mM increased the silica shell thickness from 160 to 280 nm, demonstrating the significant impact of surfactant concentration on shell formation. Si-ACS particles exhibited a surface area of 55.54 m²/g and a pore volume of 0.64 cm³/g, as evidenced by BET measurements, indicating successful mesopore formation critical for catalytic and adsorption applications. The materials were further modified with cholesterol and tetraethyl pentaamine (TEPA), which was confirmed by FT-IR analysis. Additionally, the study demonstrates the application of these functionalized nanostructures as chromatographic columns. In particular, the dual-mode interactions of Si-ACS-CHOL-TEPA significantly improve the separation of phthalate esters, thereby highlighting the potential of these materials in advanced analytical and biotechnological applications.