Nuclear magnetic resonance techniques for the structural characterization of siloxane–oxide hybrid materials
2000; Elsevier BV; Volume: 19; Issue: 3 Linguagem: Inglês
10.1016/s0277-5387(99)00361-7
ISSN1873-3719
AutoresFlorence Babonneau, Jocelyne Maquet,
Tópico(s)Lanthanide and Transition Metal Complexes
ResumoThe objective of this paper is to discuss the appropriateness of various solution and solid state NMR techniques to describe structural aspects of siloxane–oxide hybrid systems prepared by sol-gel processes. Co-hydrolysis of organosilanes and metallic alkoxides can promote either self-condensation or co-condensation reactions between the different precursors, and this will control the structural homogeneity of the final network. Solution state 29Si and 17O NMR can give unique information on the formation and stability of co-condensing species. In the final gels, solid state 29Si MAS used in conjunction with cross-polarization (CP) and related two-dimensional 29Si–1H heteronuclear NMR correlation techniques, provides detailed information on dipole–dipole coupled 29Si and 1H species among different molecular moieties. Finally, the use of 17O MAS NMR with the newly developed MQ MAS sequence that provides a direct identification of the various oxo bridges will be discussed.
Referência(s)