Preparation and study of the surface-layer composition of chemically modified silica nanoparticles

The in situ treatment of silica nanoparticles by trimethoxy-(1H,1H,2H,2H-perfluoro-1-octyl)silane results in the formation of materials possessing hydrophobic and superhydrophobic properties. The stability of the final sol, average particle size, degree of polydispersity of particles, and limiting wetting angle substantially depend on synthesis conditions such as temperature, nature and homogeneity of the dispersion medium (solvent), and the concentration of the modifier. An approach is proposed based on a dynamic determination of oxygen concentration in air flux when oxygen interacts with the sample at high temperature (oxithermography) as an alternative to traditional analysis techniques used in the layer of an organic substance chemically engrafted to silica surface. The proposed method allows us to detect both volatile, sorbed-at-the-surface and nonvolatile, covalently fixed components of an organic nature, which can react with a molecular oxygen in a temperature range reaching 800°C. © 2015, Pleiades Publishing, Ltd.