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RESEARCH PRODUCT

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4-(4-Carboxyphenyl)-3,5-dioxo-1,2,4-triazolidin-1-yl moieties resulting from 4-(3,5-dioxo-1,2,4-triazolin-4-yl)benzoic acid (U4A) randomly attached to 1,4-polybutadiene form supramolecular aggregates which act as effective junction zones in new thermoplastic elastomers. Deuteron nuclear magnetic resonance (2H NMR) spectroscopy was used to investigate the molecular dynamics of the polymer backbone and the junction zones in selectively labelled samples. The spectra show motional heterogeneity along the polymer chain as well as in the supramolecular domains. Polybutadiene segments which are adjacent to these polar clusters are restricted in their mobility, even at temperatures 100 K above the glass transition temperature Tg. The immobilized regions are estimated to involve about two monomeric units. The functional groups in the supramolecular structures are rigid or exhibit 180° -phenyl flips dependent on their location in the middle or in the edges, respectively. Polar units which are not enclosed in the clusters and dispersed in the polymer matrix undergo fast isotropic motions.