resumo
Hybrid materials have been prepared by gamma-irradiation of a mixture of polydimethylsiloxane silanol-terminated, and the alkoxides tetraethylortosilicate and zirconium propoxide, using a Co-60 gamma source. No other chemicals were added to these precursors. Samples have been prepared with different concentrations of polymer and different mixtures of the metallic alkoxides. The obtained samples were heat-treated at several temperatures. The as prepared hybrids are monolithic and transparent. After heat-treatment in air at 650 degrees C the material remained monolithic if they were prepared from a mixture with alkoxide content larger than that of the polymer, whereas those prepared from a mixture with larger content of polymer reduced to coarse grains. These results indicate that the hybrid material matrix can consist of either inorganic oxide in the former case with embedded polymeric crosslinked chains or a polymeric matrix in the latter case with embedded inorganic oxide domains. Elemental analysis showed that the carbon release originates initially from reactions between the alkoxides whereas at the higher temperature it results from the polymer degradation. RBS analysis showed that Si is present in the material with an almost constant relative concentration but Zr is not homogeneously distributed, presenting different relative concentrations on the top and bottom surfaces of the same sample, depending on the composition. (c) 2007 Elsevier B.V. All rights reserved.
palavras-chave
SOL-GEL PROCESS; NANOCOMPOSITES
categoria
Instruments & Instrumentation; Nuclear Science & Technology; Physics
autores
Gomes, SR; Margaca, FMA; Salvado, IMM; Leal, JP; Marques, C; Alves, E; Ferreira, LM; Falcao, AN
nossos autores
