Supramolecular polymers (SPs) are formed by self-assembly of monomeric units, which are connected through dynamic non-covalent interactions such as hydrogen bonding or metal-ligand coordination. The reversibility of these bonds can be exploited to disassemble SPs back into their monomeric species. This can be achieved in a controlled manner by the application of a specific stimulus, such as temperature, light or a mechanical force. Most stimuli-responsive materials are based on a single type of supramolecular interaction; however, the combination of multiple (orthogonal) supramolecular interactions in one material allows, in principle, creating multi-responsive shape-memory polymers. Despite many studies that have investigated the orthogonality of a number of supramolecular binding motifs for several polymeric systems in solution, very few reports have explored the potential of such interactions to create multi-responsive solid polymeric materials.<br/><br/>This contribution will discuss the synthesis and properties of a new supramolecular polymer system based on two orthogonally bound interpenetrated supramolecular networks. Both networks are based on trifunctional polypropylene oxide backbones which are terminated by either 2,6-bis(1’-methylbenzimidazolyl)pyridine (Mebip) ligands or ureipyrimidinone (UPy) groups. Cross-linking is achieved by complexing the Mebip motifs to Zn<sup>2+</sup> or UPy dimerization via hydrogen bonding, respectively. The orthogonal binding of the metal complex and hydrogen bonding motifs was established on the basis of UV-Vis titrations, dynamic mechanical thermal analysis, and small-angle X-ray scattering, which suggest that the properties of the networks are dictated by the phase segregation of the binding motifs into well-defined hard phases. The metal complexes and UPy dimers can be addressed selectively with orthogonal stimuli, which provide this material with shape-memory characteristics.

Shape-memory polymers based on orthogonally bound interpenetrated supramolecular networks

254th National Meeting (2017)

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