Otro
Small-angle X-ray scattering and X-ray absorption near-edge structure study of iron-doped siloxane-polyoxyethylene nanocomposites
Registro en:
Journal of Applied Crystallography. Copenhagen: Blackwell Munksgaard, v. 36, p. 405-409, 2003.
0021-8898
10.1107/S0021889803000517
WOS:000182284400005
Autor
Chiavacci, L. A.
Dahmouche, K.
Briois, V
Santilli, Celso Valentim
Bermudez, V. D.
Carlos, L. D.
Jolivet, J. P.
Pulcinelli, Sandra Helena
Craievich, A. F.
Resumen
The local and medium-range structures of siloxane-POE hybrids doped with Fe(III) ions and prepared by the sol-gel process were investigated by X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structure (EXAFS) and small-angle X-ray scattering (SAXS), respectively. The experimental results show that the structure of these composites depends on the doping level. EXAFS data reveal that, for low doping levels ([O]/[Fe] > 40, oxygens being of the ether-type of the POE chains), Fe(III) ions are surrounded essentially by a shell of chlorine atoms, suggesting the formation of FeCl4- anions. At high doping levels ([O]/[Fe] < 20), Fe(III) ions interacts mainly with oxygen atoms and form FeOx species. The relative proportion of FeOx species increases with iron concentration, this result being consistent with the results of SAXS measurements showing that increasing iron doping induces the formation of iron-rich nanodomains embedded in the polymer matrix.