Influence of Particle Diameter on Surface Silanol Structure, Hydration Forces, and Aggregation Behavior of Alkoxide‐Derived Silica Particles

Abstract

The effects of silica particle diameter on dispersion and aggregation behavior in water were analyzed, using alkoxidederived silica powders with particle diameters of 8 -260 nm. The present study focused on the relationships between the surface silanol structure and the interaction forces between solid surfaces in water. The surface silanol structure and interaction between particles were determined using Fourier transform infrared spectroscopy, Fourier transform nearinfrared spectroscopy, and atomic force microscopy. For relatively large particles (>30 nm in diameter), the surface silanols primarily were hydrogen-bonded silanols, and isolated silanols disappeared. The hydrogen-bonded silanols formed a hydrogen-bonded water layer on the particle surface; therefore, the additional hydration force was strong between these relatively large particles. In contrast, the surface density of isolated silanols increased as the particle diameter decreased to <30 nm, and the additional hydration force between ultrafine powders disappeared. The aggregation behaviors of alkoxidederived silica powders were dependent on the hydration force, which was changed by the surface silanol structure.

Silica Surface Features and Their Role in the Adsorption of Biomolecules: Computational Modeling and Experiments

“…It has been claimed that both fumed and precipitated silica surfaces exhibit a density of isolated silanols of about 1.1 nm -2 . 115 Other studies, however, would indicate that the balance between isolated and H-bonded silanols is variable and depends on the geometry of the silica particles, and most notably on their size as the smaller particles have a lesser number of isolated silanols, presumably due to constraints imposed by surface curvature, 116 whereas on fully hydrated particles with a diameter > 30 nm, only H-bonded silanols were observed.…”

Preliminary Evaluation of Median Lethal Concentrations of Stöber Silica Particles with Various Sizes and Surface Functionalities Towards Fibroblast Cells

“…Moreover, the density of the free silanol groups is related to the surface curvature of the particle, i.e. their density decreases with increasing diameter [34]. Hence, cytotoxicity is expected to decrease with increasing diameter.…”

Monodisperse SiC/vinyl ester nanocomposites: Dispersant formulation, synthesis, and characterization

“…The absorption band in the range from 3550 to 3300 cm À1 is commonly assigned to hydroxyl group vibrations. 17 Additionally, the absorption band at 1100 to 1070 cm À1 is due to the Si-O stretching vibrations of the different silicon oxycarbide, SiO 2 C 2 and SiO 3 C, species. These species have been reported to be the first layers of oxidation of SiC.…”