Solvent free sol-gel based synthesis of soft magnesium silicate

In this study, soft magnesium silicates were prepared via sol-gel method starting from diethylphosphatoethyltriethoxysilane (SiP), magnesium ethoxide and magnesium acetate. The thermal reaction of the different systems without any solvent was studied by a thermogravimetric analysis coupled to gas chromatography and mass spectroscopy in order to identify the volatile by-products and then suggest a reaction mechanism. The identification of several by-products formed during the reactions evidenced a non-hydrolytic sol-gel based route between the ethoxy and acetoxy groups of magnesium ethoxide and magnesium acetate respectively with the ethoxy groups of SiP. In addition, X-ray photoelectron spectroscopy analyses highlighted the creation of Mg-O-Si bonds. The viscoelastic behavior of the reactive systems allowed to confirm the formation of the network but also the determination of the gelation time. It corresponded respectively to 2150 and 1020 s for the reaction between magnesium ethoxide and SiP and magnesium acetate and SiP carried out at 170 degrees C. All these data confirm the formation of a soft inorganic network in that range of temperature. [GRAPHICS] .

Automated summary

Soft magnesium silicates were prepared via sol-gel method, and the thermal reaction and formation mechanism of the products were studied. The results indicated the formation of a soft inorganic network at 170 degrees C.