J. Phys. II France
Volume 5, Numéro 5, May 1995
Page(s) 665 - 675
DOI: 10.1051/jp2:1995156
J. Phys. II France 5 (1995) 665-675

EXAFS Study of Halato-Telechelic Polymers End-Capped With Group IVb Metal Carboxylates at Room and Low Temperatures

G. Vlaic1, G. Navarra2, J.-R. Regnard3, C.E. Williams4 and R. Jérôme5

1  Dipartimento di Scienze Chimiche, Università di Trieste, 34127 Trieste, Italy, and Sincrotrone Trieste SCpA, Padriciano 99, 34012 Trieste, Italy
2  Dipartimento di Scienze Chimiche, Università di Cagliari, 09124 Cagliari, Italy
3  CEA, Département de Recherche Fondamentale sur la Matière Condensée, SP 2M-PI, 38054 Grenoble Cedex 9, France, and University Joseph Fourier, B.P. 53X, 38041 Grenoble Cedex, France
4  LURE, University of Paris-Sud, 91405 Orsay, France
5  Center for Education and Research on Macromolecules (CERM), University of Liège, Sart Tilman B6, 4000 Liège, Belgium

(Received 30 December 1994, accepted 8 February 1995)

The EXAFS analysis at 300, 70 and 5 K has shown that the thermal disorder is very low in a carboxylato telechelic polybutadiene neutralized with an increasing excess of Zr isopropoxide. Two types of Zr-O bonds in the first shell account for the experimental data. The Zr-O distances and number of oxygen neighbours in the two subshells are found to be independent of temperature in the investigated range. The proportion of Zr in the samples has no effect on the total number of oxygen atoms around Zr, in contrast to their relative distribution in the two subshells. The number of Zr atoms increases in the second shell with the total amount of this metal. Upon increasing degree of neutralization from 200 to 600%, the static disorder increases together with a strong reduction of the dynamic part of the Debye-Waller (DW) factor. At a high degree of neutralization ( $> 400\%$), the DW factor for the Zr-Zr bond is largely independent of temperature. These observations agree with formation of Zr polynuclear microdomains, the size and rigidity of which increase with the Zr content, in good agreement with the profound changes previously reported in the viscoelastic properties of these materials.

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