Glass transition of polydimethylsiloxane-vanadate hybrid materials studiedthrough O-17 and V-51 NMR

Nuclear magnetic resonance (NMR) analysis of quadrupolar nuclei is shown to be a robust and powerful tool for studying glass transition of elastomeric nano-composites. In the case of polydimethylsiloxane-vanadate (PDMSV) mate rials, single pulses on O-17 and V-51 nuclei allow an observation of the ef fect on the quadrupolar splitting of motional changes above the calorimetri c glass transition (177 +/- 1 K). Moreover, intensities of quadrupolar echo es are found sensitive to changes of motional correlation times occurring a t the glass transition. Their variations give rise to consistent values of T-g (= 184 +/- 5 K for O-17, = 178 +/- 2 K for V-51). These results obtaine d through twin probing NMR analysis of half integer quadrupolar nuclei unam biguously confirm previous assumptions on chemical homogeneity and co-polym er effects. (C) 2000 Elsevier Science B.V. All rights reserved.