Supramolecular networks obtained from polymers with self-assembling end groups result in thermoplastic elastomers with well-defined and tailorable thermal transitions.[1] So far, however, most examples have relied on low molecular weight polymer segments, as the end group association becomes progressively inefficient at increasing polymer molecular weight. This severely limits the materials’ large strain mechanical properties and consequently the processing options, because these properties largely depend on polymer entanglement. Here, we present how the supramolecular modification of different high molecular weight polymers can be employed to obtain a wide variety of elastomeric or thermoplastic materials with often extraordinary thermomechanical property profiles and adequate large strain mechanical response. To this end, we made use of molecularly uniform oligopeptide end groups that self-assemble into well-defined, one-dimensionally extended nanostructures.[2] This particular feature renders them capable to co-assemble with a corresponding low molecular weight additive, which in turn results in aggregation that is independent of the chosen polymer molecular weight. Thus for entangled polymer materials, we show that such aggregates provide an effective structural reinforcement at additive concentrations as low as 5 wt%, which leads to a robust polymer network that remains thermodynamically stable up to the dissociation temperature. We demonstrate that this approach constitutes a universal pathway to novel supramolecular elastomers and thermoplastic materials with unusual combinations of high softening temperatures, strain at break, yield strength, ductility, toughness, which therefore opens up new processing avenues. References: [1] S. Seiffert, Supramolecular Polymer Networks and Gels, in Adv. Polym. Sci. 2015, 268. [2] E. Croisier, S. Liang, T. Schweizer, S. Balog, M. Mionić, R. Snellings, J. Cugnoni, V. Michaud, H. Frauenrath, Nat. Commun. 2014, 5, 4278.