Mechanically interlocked networks (MINs) have emerged as an encouraging platform for the development of mechanically robust yet adaptive materials. However, the difficulty in reversibly breaking the mechanical bonds poses a real challenge to MINs as customizable and sustainable materials. Herein, we couple the vitrimer chemistry with mechanically interlocked structures to generate a new class of MINsreferred to as mechanically interlocked vitrimers (MIVs)to address the challenge. Specifically, we have prepared the acetoacetatedecorated [2]rotaxane that undergoes catalyst-free condensation reaction with two commercially available multiamine monomers to furnish MIVs. Compared with the control whose wheels are nonslidable under applied force, our MIVs with slidable mechanically interlocked motifs showcase enhanced mechanical performance including Young's modulus (18.5 ± 0.9 vs 1.0 ± 0.1 MPa), toughness (3.7 ± 0.1 vs 0.9 ± 0.1 MJ/m 3 ), and damping capacity (98% vs 72%). The structural basis behind unique property profiles is demonstrated to be the force-induced host−guest dissociation and consequential intramolecular sliding of the wheels along the axles. The peculiar behaviors represent a consecutive energy dissipation mechanism, which provides a complement to other pathways that mainly depend on the breaking of sacrificial bonds. Moreover, by virtue of the vitrimer chemistry of vinylogous urethanes, we impart reprocessability and chemical recyclability to the MINs, thereby empowering the reconfiguration of the networks without breaking of the mechanical bonds. Finally, it is disclosed that the intramolecular motions of [2]rotaxanes could accelerate the dynamic exchange of the vinylogous urethane bonds via loosening the network, suggestive of a synergistic effect between the dual dynamic entities.

The intrinsic relationship between the properties of green fluorescent protein (GFP) and its encapsulated small molecular light machine has spurred many biomimicking studies, aiming at revealing the detailed mechanism and further promoting its wide applications in different disciplines. However, how to build a similar confined microenvironment to mimic the cavity of βbarrel and the fluorescence turn-on process is a fundamental challenge for both chemists and biologists. Herein, two distinct exoand endo-functionalized tetraphenylethylene (TPE)-based M 12 L 24 nanospheres with precise distribution of anchored TPE moieties and unique photophysical properties were constructed by means of a coordination-driven self-assembly strategy. Under dilute conditions, the nanospheres fluoresce stronger than the corresponding TPE subcomponents. Meanwhile, the endo-functionalized sphere is able to induce a higher local concentration and more restrained motion of the enclosed 24 TPE units compared with that of exo-functionalized counterpart and thus induce much stronger emission due to the restriction of the rotation of the pendant TPE units. The biomimetic methodology developed here represents a promising way to understand and construct artificial GFP materials on the platforms of supramolecular coordination complexes.

Nature has engineered delicate synergistic covalent and supramolecular polymers (CSPs) to achieve advanced life functions,s uch as the thin filaments that assist in muscle contraction. Constructing artificial synergistic CSP materials with bioinspired mechanically adaptive features,h owever, represents ac hallenging goal. Here,w er eport an artificial CSP system to illustrate the integration of ac ovalent polymer (CP) and as upramolecular polymer (SP) in as ynergistic fashion, along with the emergence of notable mechanical and dynamic properties which are unattainable when the two polymers are formed individually.T he synergistic effect relies on the peculiar network structures of the SP and CPs,w hich endowt he resultant CSPs with overall improved mechanical performance in terms of the stiffness,s trength, stretchability, toughness,and elastic recovery.Moreover,the dynamic properties of the SP,i ncluding self-healing,s timuli-responsiveness, and reprocessing,are also retained in the CSPs,thus leading to their application as programmable and tunable materials.

A thin filament stimulated by Ca2+ to combine with myosin is the structural basis to achieve filament sliding and muscle contraction. Though a large variety of artificial materials has been developed by mimicking muscle, the on-demand combination of the actin filament and myosin has never been precisely reproduced in polymeric systems. Herein, we show that both the combination process and the combined structure of actin filament and myosin have been mimicked to construct synergistic covalent and supramolecular polymers (CSPs). Specifically, photoirradiation as a stimulus induces the independently formed covalent polymers (CPs) and supramolecular polymers (SPs) to interact with each other through activated quadruple H-bonding. The resultant CSPs possess a unique network structure which not only facilitates the synergistic effect of CPs and SPs to afford stiff, strong, yet tough materials but also provides efficient pathways to dissipate energy with the damping capacity of the representative material being higher than 95%. Furthermore, muscle functions, for example, by becoming stiff during contraction and self-growth by training, are imitated well in our system via in situ phototriggered formation of CSP in the solid state. We hope that the fundamental understanding gained from this work will promote the development of synergistic CSP systems with emergent functions and applications by mimicking the principle of muscle movements.

Nature has been inspiring scientists to fabricate impact protective materials for applications in various aspects. However, it is still challenging to integrate flexible, stiffness-changeable, and protective properties into a single polymer, although these merits are of great interest in many burgeoning areas. Herein, we report an impact-protective supramolecular polymeric material (SPM) with unique impact-hardening and reversible stiffness-switching characteristics by mimicking sea cucumber dermis. The emergence of softness−stiffness switchability and subsequent protective properties relies on the dynamic aggregation of the nanoscale hard segments in soft transient polymeric networks modulated by quadruple H-bonding. As such, we demonstrate that our SPM could efficiently reduce the impact force and increase the buffer time of the impact. Importantly, we elucidate the underlying mechanism behind the impact hardening and energy dissipation in our SPM. Based on these findings, we fabricate impact-and puncture-resistant demos to show the potential of our SPM for protective applications.