Influence of Methanol Concentration on the Synthesis and Characteristics of Mesoporous Silica Nanoparticles: A DFT Reactivity Study

Abstract

This study explores the synthesis and comprehensive characterization of mesoporous silica nanoparticles (MSNs), with particular emphasis on the influence of methanol concentration and its electronic reactivity, examined through density functional theory (DFT). A modified Stöber method was employed, using tetramethoxysilane (TMOS) as the silica precursor, methanol (Me-OH) as the solvent, and dodecyltrimethylammonium bromide (C₁₂TMABr) as the structure-directing agent. Systematic variations in the molar ratios of TMOS, deionized water (DI-W), sodium hydroxide (NaOH), and Me-OH were performed to elucidate their effects on particle formation. The resulting materials were characterized by Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). DFT calculations provided molecular-level insight into the electron density distribution and local reactivity of the methanol–silica cluster. Specific carbon atoms (e.g., C8 and C13) were identified as reactive centers with high susceptibility to nucleophilic attack, highlighting methanol’s role in modulating hydrolysis and condensation pathways. Experimentally, variations in precursor concentrations and reaction parameters produced nanoparticles with tunable diameters (100–1301 nm), pore sizes (1.01–4.42 nm), and surface areas (815–1159 m².g^-1). These findings advance the mechanistic understanding of mesoporous silica synthesis by linking reaction chemistry with structural outcomes. The demonstrated tunability of particle size, porosity, and surface area underscores the potential of MSNs for diverse applications, particularly in drug delivery and environmental remediation.