Complex dynamics of hydrogen bonded self-assembling polymers

Supramolecular polymers, which are non-covalently bonded and formed by self association of di or trifunctional monomers exhibit, by virtue of quadrupl e hydrogen bonds, many of the properties of normal high molecular weight po lymers, e.g a dynamic rubber plateau. We focus on the molecular and coopera tive dynamics of self-assembled linear polymers and networks, studied by br oadband dielectric relaxation spectroscopy (DRs) in the frequency range fro m 10(-2) to 10(6) Hz. The Das analysis was backed up by dynamic mechanical and theological experiments. In the high temperature region two loss proces ses (alpha and alpha*) show up, the relaxation times of which obey the Voge l-Fulcher-Tammann (VFT) law. The dielectric cu process is related to the dy namic glass-rubber transition and is slightly faster than the corresponding mechanical or process. A slower (high-temperature) alpha* relaxation is id entified as chemical corresponding to the mean lifetime of the hydrogen bon ded linkages in the supramolecular chains. Its relaxation time tau (alpha*) was found to be 1 to 2 decades larger than the terminal now relaxation tim e, indicating that the relaxation of an entire chain is dominated by the jo int dynamics of many hydrogen bonds. The beta relaxation, observed in both Das and dynamic mechanical analysis (DMA) at temperatures below T-g, arises from the local junction dynamics of hydrogen bonded units in the glassy st ate. Details of the temperature dependence and the shape of the loss peaks of the alpha and alpha* relaxations will be discussed in terms of temporary physical networks and cooperativity.