Supramolecular polymers

Supramolecular polymers are a kind of polymers whose monomeric units hold together via highly directional and reversible non-covalent interactions. Unlike conventional bonded polymers, supramolecular polymers engage in a variety of non-covalent interactions that define their properties. These interactions include hydrogen bonding, π-π interaction, metal coordination, and host-guest interaction. Owing to the presence of these reversible noncovalent interactions, supramolecular polymers exhibit dynamic properties such as self-healing.

Due to the nature of supramolecular polymers, the noncovalent interactions make supramolecular polymers more dynamic and reversible. Such properties enable supramolecular polymers to construct a dynamic and reversible network, which are able to develop self-healing materials based on noncovalent bonds. Compared with self-healing materials based on covalent bonds, these supramolecular polymers-based self-healing materials can restore the initial structure and function of polymers before being exposed to damages, and can also undergo repeating damage-heal process.

To achieve the light-to-charge conversion is the prerequisite step in artificial photosynthesis systems. By incorporating electron donor and electron acceptor into the supramolecular polymers, a number of artificial systems, including photosynthesis system, can be constructed. Due to the existence of more than one interactions (π-π interaction, hydrogen bonding interaction and the like), electron donor and electron acceptor can be held together in a proper proximity to afford long-lived charge separated states. Then a light-to-charge conversion system with faster photoinduced electron transfer and higher electron-transfer efficiency can be achieved in these artificial polymers.

It is quite common that biomolecules, such as DNA,protein and the like, come into being through various noncovalent interactions in biological system. Likewise, supramolecular polymers assembles itself by means of combination of noncovalent interactions. Such formation manner endows supramolecular polymers with features, being more sensitive to external stimuli and able to render reversibly dynamic changes in structures and functions. By modifying monomeric units of supramolecular polymers with water-soluble pendants, bioactive moieties as well as biomarkers, supramolecular polymers can realize various kinds of functions and applications in biomedical field. At the same time, their reversible and dynamic nature make supramolecular polymers bio-degradable, which surmounts hard-to-degrade issue of covalent polymers and makes supramolecular polymers a promising platform for biomedical applications. Being able to degrade in biological environment lowers potential toxicity of polymers to a great extent and therefore, enhances biocompatibility of supramolecular polymers.

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