Supramolecular polymer networks self-healing

Microcrack formation and crack propagatiOTi are a common cause of material failure. To overcome this problem, supramolecular polymer networks have been developed that can self-heal on the basis of the dynamic nature of their reversible cross-links [268]. The healing can either occur in an autonomous fashion or upmi exposure to an external stimulus such as heat, light, pressure, or mechanical stress. 

Okay O (2015) Self-healing hydrogels formed via hydrophobic interactions. In Seiffert S (ed) Supramolecular polymer networks. Advances in Polymer Science. Springer, Cham... 

The reversibility of supramolecular polymers adds new aspects to many of the principles that are known from condensation polymerizations. A mixture of different supramolecular monomers, for example, will yield copolymers, but it is extremely simple to adjust the copolymer composition instantaneously by adding an additional monomer. Moreover, the use of monomers with a functionality of three or more, will give rise to a network formation. However, in contrast to condensation networks, the self-healing supramolecular network can reassemble to form the thermodynamically most favorable state, thus forming denser networks.121... 

It has also been shown that non-covalent interactions, specifically hydrogen bonds, may be used to establish healing within a supramolecular polymer blend (Cordier et al., 2008 Lehn, 2005). In the latter system, it is proposed that fracture propagates via dissociation of the weak supramolecular interactions rather than by scission of covalent bonds, so that re-assembly of the supramolecular network restores the original physical properties of the material (Burattini et al., 2009). Hydrogen-bonding appears as a suitable option for room-temperamre self-healing mbberand similar materials.(Lehn, 2005 Sijbesma, 1997). 

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