Organic-inorganic hybrid materials based on N=C=O functionalised silan modified with titanium and zirconium

Abstract

This work investigates the influence of the precursor trimethylsilil isocyanate on the sol-gel synthesis of hybrid materials. The obtained Si-O-C-N network is additionally modified by titanium and zirconium alcoxypropoxides in the range of 10 to 30 wt.%. The structure of the obtained hybrid materials before and after pyrolysis up to 1100 • C was investigated by methods of XRD, FTIR and 29 Si MAS NMR. We established that the hybrid structure was stable up to 600 • C based on IR study. The structural transformation of the hybrid materials into oxycarbonitrogen system started at 800 • C. The network of the hybrids modified by titanium remained stable and amorphous up to the final temperature of the pyrolysis (1100 • C) compared to the gels modified by more than 10 wt.% Zr. It was confirmed by XRD analysis that the last mentioned are nanocomposite materials, built from carbooxynitrogen vitreous matrix and ZrO 2 -nanocrystals (tetragonal). The NMR method verified the presence of heterometallic bonds (Si-O-Ti and Si-O-Zr) and Q 4 , ZrQ 3 or TiQ 3 , NSiO 3 and D structural units in the gels.

Preparation of nanostructured porous SiO2-Al2O3 oxycarbonitride materials obtained by a new chemical precursor method

“…The vibrations of the Si-NH 2 groups can be observed as a band at 1210-1230 cm -1 [8]. The peaks at 1080 cm -1 and 480 cm -1 are due to both stretching and deformation vibration of Si-O-Si bonds, while the deformation vibration corresponding to Si-(CH) 3 groups has appeared at 845 cm -1 and 765 cm -1 [9]. Evidence for the chemical homogeneity of the hybrid materials can be considered from the presence of peaks at 648 cm -1 , which in the bibliographic data is referred to the presence of heterometallic (Si-OAl( Si) bonds, as well as the linkages at 547 cm -1 due to deformation vibration of O-Si (Al)-O).…”