From Reinforcement to High-Performance Damping

Biomaterials such as structure proteins are constructed from limited sets of chemical building blocks and supramolecular motifs. Nevertheless, they exhibit extraordinary properties specifically tailored for a broad range of applications because hierarchical structure formation makes it possible to utilize similar supramolecular motifs without mutual interference. In the present thesis, we investigated how (β-sheet-forming oligopeptides can be used in a similar way to tailor the thermomechanical properties of elastomers in a versatile fashion. Differently from previous examples of supramolecular materials reported in literature, the formation of either small aggregates or (β-sheet fibrils was strictly controlled by the molecular structure. Moreover, due to 'self-sorting', these nanostructures coexisted in mixtures of polymers with different oligopeptide end groups of different length. Blends of polymers with matching oligopeptide termini gave rise to shape persistent thermoplastic elastomers that were inherently reinforced by the presence of cross-linked (β-sheet fibrils. In addition, these advanced materials had low melt viscosity at slightly elevated temperature, resulting in thermoresponsive materials or elastomers with good processing properties. On the other hand, blends of polymers with non-matching oligopeptide termini formed novel 'interpenetrating supramolecular networks' that may have a potential in self-healing applications and proved to be high-performance vibration damping materials. Finally, one of these novel 'interpenetrating supramolecular network' materials was used as matrix for the formation of nanocomposites. The addition of carbon black nanoparticle fillers to the matrix material gave rise to highly efficient damping materials for applications using constrained layer structures.