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  • 1 University “Politehnica” of Timisoara Faculty of Industrial Chemistry and Environmental Engineering P-ta Victoriei no. 2 300006 Timisoara Romania
  • | 2 West University of Timisoara, Research Center “Thermal Analysis in the Environmental Field” Str. Pestalozzi, no. 16 300115 Timisoara Romania
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Abstract  

Hybrid organic–inorganic materials, silica–diol, were synthesized by the sol–gel process from mixtures of tetraethylorthosilicate (TEOS) and diols: ethylene glycol (HO–CH2–CH2–OH) and 1,3 propane diol (HO–CH2–CH2–CH2–OH), in acid catalysis. The gels have been synthesized for a molar ratio H2O:TEOS = 4:1 and different molar ratios diol/TEOS: 0.25; 0.5; 0.75; 1.0; 1.25 and 1.5. The resulting gels were studied by thermal analysis and FT-IR spectroscopy, in order to evidence the interaction of diols with silica matrix. Thermal analysis indicated that the condensation degree increases with the molar ratio diol/TEOS until a certain value. The thermal decomposition of the organic chains bonded within the silica network in the temperature range 250–320 °C, leaded to a silica matrix with modified morphology. The adsorption–desorption isotherms type is different for the samples with and without diol. Thus, the specific surface areas have values <11 m2/g for the samples without diol and >200 m2/g for the samples with diols, depending on the annealing temperature.

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