Photoresponsive Supramolecular Polymers: From Light-Controlled Small Molecules to Smart Materials

Photoresponsive supramolecular polymers are well-organized assemblies based on highly oriented and reversible noncovalent interactions containing photosensitive molecules as (co-)monomers. They have attracted increasing interest in smart materials and dynamic systems with precisely controllable functions, such as light-driven soft actuators, photoresponsive fluorescent anticounterfeiting and light-triggered electronic devices. The present review discusses light-activated molecules used in photoresponsive supramolecular polymers with their main photo-induced changes, e.g., geometry, dipole moment, and chirality. Based on these distinct changes, supramolecular polymers formed by light-activated molecules exhibit photoresponsive disassembly and reassembly. As a consequence, photo-induced supramolecular polymerization, depolymerization, and regulation of the lengths and topologies are observed. Moreover, the light-controlled functions of supramolecular polymers, such as actuation, emission, and chirality transfer along length scales, are highlighted. Furthermore, a perspective on challenges and future opportunities is presented. Besides the challenge of moving from harmful UV light to visible/near IR light avoiding fatigue, and enabling biomedical applications, future opportunities include light-controlled supramolecular actuators with helical motion, light-modulated information transmission, optically recyclable materials, and multi-stimuli-responsive supramolecular systems.

Automated summary

Photoresponsive supramolecular polymers are highly organized assemblies with photosensitive molecules as monomers, showing reversible changes in geometry, dipole moment, and chirality upon light stimuli. They have broad applications in smart materials, including light-driven soft actuators, fluorescent anticounterfeiting, and light-triggered electronic devices. This review focuses on the light-activated molecules used in photoresponsive supramolecular polymers and the different changes induced by light. It also highlights the disassembly, reassembly, actuation, emission, and chirality transfer of these polymers. Future opportunities and challenges, such as using visible/near IR light and enabling biomedical applications, are also discussed.