Light-Induced Transformation from Covalent to Supramolecular Polymer Networks

Stimuli-responsive polymers have demonstrated significant potential in the development of smart materials due to their capacity to undergo targeted property changes in response to external physical or chemical stimuli. However, the scales of response in most existing stimuli-responsive polymer systems are mainly focused on three levels: functional units, chain conformations, or polymer topologies. Herein, we have developed a covalent polymer network (CPN) capable of converting into a supramolecular polymer network (SPN) within bulk materials directly at the scale of polymer network types. This transformation is enabled by specifically designed covalent moieties that upon UV exposure reveal quadruple hydrogen bonding sites, allowing the formation of a supramolecular network. This network-type transition from CPN to SPN induces pronounced intrinsic changes in material properties, including a substantially increased breaking elongation, lower Young's modulus, reduced fracture strength, and decreased creep resistance, marking a shift from a stable, rigid structure to a dynamic, adaptable one. These findings provide new insights into the design of advanced stimuli-responsive polymer materials through network-type transformations, opening new avenues for applications in smart and multifunctional materials.