Synthesis via sol–gel process and characterization of novel organic–inorganic coatings

Organic–inorganic coatings were synthesized from tetraethoxysilane (TEOS) and vinyltriacetoxysilane (VTAS) via dual process involving sol–gel reaction and radical polymerization. The deposition of the films was carried out using the spin-coating technique with the sample holder spinning at 1500 rpm. In order to determine the nature of products formed during the sol–gel reaction (i.e. polymerization) and to study the kinetics of this reaction, Fourier transform infrared (FTIR) spectroscopy experiments were performed. This technique allows also determining the optimal temperature of the final heat treatment. Thermogravimetric analysis (TGA) was used to study the influence of the ratio of organic and inorganic components on the thermal stability of the organic–inorganic hybrid, while differential scanning calorimetry (DSC) was used to determine its glass transition temperature. The chemical structure of this prepared hybrid material is also studied using FTIR with attenuated total reflection (ATR) device.Finally, the homogeneity of the chemical composition of the synthesized materials was checked by using the elemental distributions obtained by an energy dispersive spectrometer (EDS) attached to a scanning electron microscope (SEM). Moreover, nanoindentation measurements on thin films show enhanced hardness and elastic modulus with increasing silicate network.

► Highly cross-linked dense hybrid material synthesized using TEOS and VTAS precursors.
► The thermally cured hybrid material forms a uniform and defect-free thin film.
► Increase of the amount of organic constituent leads to decrease in the hardness.