Insights into the Correlation of Microscopic Motions of [2]Daisy Chains with Macroscopic Mechanical Performance for Mechanically Interlocked Networks.

Mimicking filament sliding in sarcomeres using artificial molecular muscles such as [2]daisy chains has aroused increasing interest in developing advanced polymeric materials. Although few bistable [2]daisy chain-based mechanically interlocked polymers (MIPs) with stimuli-responsive behaviors have been constructed, it remains a significant challenge to establish the relationship between microscopic responsiveness of [2]daisy chains and macroscopic mechanical properties of the corresponding MIPs. Herein, we report two mechanically interlocked networks (MINs) consisting of dense [2]daisy chains with individual extension (MIN-) or contraction (MIN-) conformations decoupled from a bistable precursor, which serve as model systems to address the challenge. Upon external force, the extended [2]daisy chains in MIN- mainly undergo elastic deformation, which is able to assure the strength, elasticity, and creep resistance of the corresponding material. For the contracted [2]daisy chains, long-range sliding motion occurs along with the release of latent alkyl chains between the two DB24C8 wheels, and accumulating lots of such microscopic motions endows MIN- with enhanced ductility and ability of energy dissipation. Therefore, by decoupling a bistable [2]daisy chain into individual extended and contracted ones, we directly correlate the microscopic motion of [2]daisy chains with macroscopic mechanical properties of MINs.