Dynamic Hydrogels Using Movable Supramolecular Cores to Prepare Multiarm Macromer Analogs

The macroscopic properties of polymer hydrogels are fundamentally governed by the network composition, structural topology, and cross-linking mechanisms. In this study, we prepared dynamic-covalent hydrogels from multiarm polyethylene glycol (PEG) analogs, using movable supramolecular cores to prepare 4-arm PEG mimics. This new architecture was achieved by using cucurbit[8]uril (CB[8]) host–guest complexes as functional cores for acylhydrazine-modified telechelic guests, followed by cross-linking with linear bis-aldehyde functionalized PEG chains via dynamic-covalent acylhydrazone bond formation. Rapid dynamics of the CB[8]–guest complexes comprising the movable core led to highly dynamic viscoelastic properties. Hydrogels with slow dynamic CB[8]–guest complexes as the movable core exhibited exceptional mechanical properties with deformation rate-dependent characteristics. This material showed extreme stretchability, elongating up to 70 times its original length before breaking. Comparative analysis with conventional hydrogels containing tetravalent macromonomers with static cores revealed that association–dissociation kinetics of the host–guest complexes play a key role in mediating the observed rate-dependent mechanical properties. This work offers the first successful design and fabrication of hydrogels prepared from 4-arm PEG analogs incorporating movable and dynamic CB[8] host–guest cores, thereby establishing a new paradigm in hydrogel engineering.