Nature does not only accept the inevitable presence of disorder in structural materials but even plays with it: it controls the placement of disorder on some length scales, uses it to create structures on others, and implements structural gradients between ordered and disordered domains to guide external fields. The result is the creation of carefully optimized materials that often contain network structures on different length scales. We implement similar concepts in synthetic elastomers and thermoplastic polymers with the aim to design polymer materials with a broad range of mechanical properties. For example, we have obtained supramolecular elastomers based on mixtures of mono- and difunctional oligopeptide-modified polymers. Self-assembly of the oligopeptides by hydrogen-bonding results in a network of nanofibrils that serve to reinforce the resulting elastomers, which show excellent elastic properties, high stiffness, and sharp melting transitions at high melting temperatures. Employing different oligopeptides results in self-sorting self-assembly and thus interpenetrating supramolecular networks. The level of complexity can further be increased by incorporating two immiscible, flexible and glassy polymers, in a way that the glassy domains form an additional percolation network. In such hierarchically structured materials, the various topologically independent supramolecular networks undergo different frequency-dependent rheological solid-fluid transitions, which results in high performance damping materials with high stiffness. A final example are novel thermoplastic polyamide materials with engineered crystallinity that comprise networks of crystalline components on different length scales and exhibit excellent strength and stiffness combined with a very high ductility.<br/>

Playing with hydrogen bonding and network formation in the design of supramolecular elastomers and thermoplasts

254th National Meeting (2017)

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