Stimuli-Triggered Dynamic Transformations in Supramolecular Polymers

Supramolecular polymers represent ordered nanostructures that are held together by highly directional noncovalent bonds and can undergo reversible self-assembly. Their noncovalent nature imparts stimuli-responsive character to supramolecular polymers, making them appealing for the development of intelligent soft materials. As compared to the inherent responsiveness originating from the noncovalent connection units, incorporating additional stimuli-responsive units into the monomeric structure allows customization of stimuli-responsiveness for supramolecular polymers. Stimuli-triggered changes at the molecular level can amplify into macroscopic effects at the supramolecular level due to the ordered arrangement of monomers. This review summarizes recent progress on stimuli-triggered transformations in supramolecular polymers, categorizing them into five types: (i) depolymerization into monomers, (ii) transformations within different types of supramolecular polymers, (iii) post-stabilization of supramolecular polymers, (iv) activation of dormant monomers for in situ polymerization, and (v) transient polymerization with programmable lifetimes. Additionally, recent progress in unconventional responsiveness due to coupled equilibria in complex supramolecular systems is outlined. Emphasis is on monomeric structure design principles and accumulated property changes in response to stimuli, aimed at stimulating further research in the stimuli-responsive supramolecular polymer field.