Analysis on the Influence of Component Ratio on Properties of Silica/Montmorillonite Nanocomposites

Silica/montmorillonite (MMT) nanocomposites (SMCs) were prepared by generating SiO₂ nanoparticles on an MMT surface using an organic/inorganic hybrid technique with different ratios of tetraethylorthosilicate (TEOS) to MMT (10:1, 20:1 and 40:1). The hydrolysis and polycondensation reactions were controlled by TEOS when it was incorporated into the internal space of the MMT. The delamination and intercalation of the MMT layers were closely related to the TEOS/MMT ratio. The surface chemistry and particulate morphology, thermal properties, pore structure and hygroscopicity of nanocomposites were investigated. The results showed that silica nanoparticles could be intercalated into a layered MMT and induced a high specific surface area (~474 m²·g^-1). At a lower ratio (10:1 and 20:1), the dispersed layers could be created from the stack MMT layers and incorporated into a silica matrix, resulting in an increased thermal stability and a decreased pore size. A higher ratio (40:1) caused the intensive self-condensation of the silanol groups, leading to a negative effect on the sol penetration to the MMT. The hydrophilicity of the SMCs increased significantly due to the synergistic effect of the hydroxyl groups and pore structure caused by silica incorporation. A mechanism concerning the effect of component ratio was also proposed for synthesizing this nanocomposite based on the research results. The potential applications of this heterostructured nanocomposites could be summarized as a desiccant, functional fillers, and pollutant disposal.