Structural influence of the carbon chain length in hybrid materials obtained from zirconium n-propoxide and diols
✍ Scribed by J. Chaibi; M. Henry; H. Zarrouk; N. Gharbi; J. Livage
- Publisher
- Springer
- Year
- 1995
- Tongue
- English
- Weight
- 532 KB
- Volume
- 4
- Category
- Article
- ISSN
- 0928-0707
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✦ Synopsis
Zirconium n-propoxide Zr(OP1 ~)4 has been chemically modified by 1,3-propanediol and 1,3-butanediol with molar ratio r = 0.5, 1 and 2. The properties of the hybrid organic-inorganic materials obtained after drying at 100°C for 24 hours have been measured by thermal analysis, X-ray diffraction, infra-red spectroscopy and 13C NMR with cross-polarisation at magic angle spinning. Chemical modification of the zirconium precursor at a molecular level has been clearly detected, with a bridging coordination mode for both diols. If the coordination mode of the diols cannot be changed by increasing the carbon chain length, it was found using ~3C CP MAS NMR that the local order is much more well-defined when the reactivity of both OH groups are not the same. Thus, using 1,3-butanediol which has a primary and a secondary OH group, it is possible to obtain after complete modification (r = 2) a highly homogeneous hybrid polymer which transforms directly into tetragonal zirconia below 400°C. With other diols (1,2-ethanediol and 1,3-propanediol), the hybrid materials transform into tetragonal zirconia above 400°C through a decomposition process involving several steps. Then playing with the carbon chain length and/or the steric hindrance around the OH groups provides an easy way to monitor the ultrastructure of these hybrid materials, and allows a better control of the gel ~ oxide transformation.