sol-gel process

Proton conductive organic-inorganic membranes were synthesized based on acrylic monomers and silica inorganic component, derived as a result of sol-gel transformation of precursor – 3-methacryloxypropyltrimethoxysilane (MAPTMS). Kinetics of polymerization in situ was investigated by laser interferometry. Membranes characterization includes water and methanol uptake, contact angle and proton conductivity at different temperatures. Activation energy values for proton conductivity in prepared membranes were evaluated.

The main methods of synthesis of magnesium-aluminate spinel powder their features and advantages were analyzed. The character of the physicochemical interaction of components in theMgO–Al2O3 system physical and crystallographic characteristics and structural parameters of thecrystalline lattice of magnesium-aluminate spinel wereresearched. The synthesis conditions arepresented and qualitative comparison of the possibilities of synthesis methods in terms of theproperties of spinel powders are made.

Hybrid polymer-inorganic membranes with varied composition of polymeric matrix were synthesized by UV-curing of a mixture of acrylic monomers with simultaneous formation of inorganic network via sol-gel reaction of tetraethoxysilane. Composition of polymeric counterpart was varied by changing the ratio of hydrophilic and hydrophobic monomers, whereas the content of inorganic counterpart was maintained constant. Morphology, thermal behavior and water uptake of membranes were investigated.

The paper is devoted to quantum-chemical calculation of tetraethoxysilane (TEOS) structure by different methods: РМ6, Hartree-Fock and DFT. PM6 method was found to be optimal. Kinetic parameters (activation energy and preexponential factor) of hydrolysis of TEOS molecule were evaluated using quantum-chemical calculation.  Key words: quantum-chemical calculation, PM6, sol-gel process, tetraethoxysilane, rate constant of hydrolysis.  

The sol-gel systems of tetraethoxysilane (TEOS) – solvent – water systems at gelation viscosity dynamics has been investigated by means of viscosimetry. The influence of different factors (temperature, concentration of initial substances and the sol-gel process initiator) on the gelation rate has been established. The measurement of viscosity gradient dependence allowed to determine an elastic and friction components of viscosity using optimization method in the ORIGIN 5.0. program.

Kinetic peculiarities of the early stages of the processes of acid-catalyzed hydrolysis and condensation in sol-gel systems tetraethoxysilane (TEOS)–ethanol–water have been investigated by gas chromatography. Kinetic parameters of the process, evaluated using quantum-chemical calculations, satisfactorilly coincide with the ones determined experimentally.