Electron Paramagnetic Resonance Study of Cu2+-Intercalated Bentonites
| Reference | Presenter | Authors (Institution) | Abstract |
|---|---|---|---|
| 16-033 | Igor D Almeida Silva | Donoso, J.P.(Universidade de São Paulo); Magon, C.J.(Universidade de São Paulo); Silva, I.D.(Universidade de São Paulo); Benavente, E.(Universidad Tecnologica Metropolitana); Gonzalez, G.(Universidad de Chile); | Intercalation of poly(ethylene oxide) PEO complexes in layered clays have been the object of a great deal of research in the last decade because of their technological importance and the scientific interest for the study of polymer chain conformation in a nanoscopically confined space [1,2]. This work presents the study of the coordination environment of Cu2+ ions in Cu-PEO intercalated bentonites using EPR techniques [3]. X-Band CW-EPR spectra measured at 50 K presents features characteristic of isolated Cu2+ ions in axially distorted sites. In addition, a small signal assigned to oxygen vacancies in the silica layer of the bentonite was observed. The covalency parameter related to the in-plane ?-bounding between copper 3d orbital and ligand orbitals was calculated using the Spin Hamiltonian parameters. A more detailed information of the coordination environment of the Cu2+ in the nanocomposite was obtained with the high resolution pulse EPR technique HYSCORE performed at both, the Cu2+ and the oxygen vacancy signals. The spectrum at the copper position shows hyperfine interaction between Cu2+ ions and 1H nuclei at the PEO. Assuming a poit dipole approximation the distance between the Cu2+ ion and the protons of the PEO was estimated to be 0.24 nm. The HYSCORE spectrum at the vacancy position shows the interaction between the unpaired spin and Al-27 nuclei at the bentonite structure. Financial support from CeRTEV, Center for Research, Technology, and Education on Vitrous Materials (FAPESP 2013/07793-6) and CAPES are acknowledge.
1: K. Chrissopoulou et.al. Macromolecules 44 (2011) 9710–9722
2: S. Zhua et.al. Applied Surface Science 276 (2013) 502– 511
3: J.P. Donoso et al. J. Phys. Chem. C 117 (2013) 24042-24055.
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