Structure of magnetic poly(oxyethylene)-siloxane nanohybrids doped with Fe-II and Fe-III


Autoria(s): Silva, NJO; Dahmouche, K.; Santilli, Celso Valentim; Amaral, V. S.; Carlos, L. D.; Bermudez, V. D.; Craievich, A. F.
Contribuinte(s)

Universidade Estadual Paulista (UNESP)

Data(s)

20/05/2014

20/05/2014

01/08/2003

Resumo

Hybrid organic - inorganic nanocomposites doped with Fe-II and Fe-III ions and exhibiting interesting magnetic properties have been obtained by the sol - gel process. The hybrid matrix of these ormosils ( organically modified silicates), classed as di-ureasils and termed U( 2000), is composed of poly( oxyethylene) chains of variable length grafted to siloxane groups by means of urea crosslinkages. Iron perchlorate and iron nitrate were incorporated in the diureasil matrices, leading to compositions within the range 80 greater than or equal to n greater than or equal to 10, n being the molar ratio of ether-type O atoms per cation. The structure of the doped diureasils was investigated by small-angle X-ray scattering (SAXS). For Fe-II-doped samples, SAXS results suggest the existence of a two-level hierarchical structure. The primary level is composed of spatially correlated siloxane clusters embedded in the polymeric matrix and the secondary, coarser level consists of domains where the siloxane clusters are segregated. The structure of Fe-III-doped hybrids is different, revealing the existence of iron oxide based nanoclusters, identified as ferrihydrite by wide-angle X-ray diffraction, dispersed in the hybrid matrix. The magnetic susceptibility of these materials was determined by zero-field-cooling and field-cooling procedures as functions of both temperature and field. The different magnetic features between Fe-II- and Fe-III-doped samples are consistent with the structural differences revealed by SAXS. While Fe-II-doped composites exhibit a paramagnetic Curie-type behaviour, hybrids containing Fe-III ions show thermal and field irreversibilities.

Formato

961-966

Identificador

http://dx.doi.org/10.1107/S0021889803008410

Journal of Applied Crystallography. Copenhagen: Blackwell Munksgaard, v. 36, p. 961-966, 2003.

0021-8898

http://hdl.handle.net/11449/34858

10.1107/S0021889803008410

WOS:000184283900001

Idioma(s)

eng

Publicador

Blackwell Munksgaard

Relação

Journal of Applied Crystallography

Direitos

closedAccess

Tipo

info:eu-repo/semantics/article