Bolstering the Mechanical Robustness of Supramolecular Polymer Network by Mechanical Bond

Supramolecular polymer networks(SPNs)are celebrated for their dynamic nature,yet they often exhibit inadequate mechanical properties.Thus far,the quest to bolster the mechanical resilience of SPNs while preserving their dynamic character presents a formidable challenge.Herein,we introduce[2]rotaxane into SPN to serve as another cross-link,which could effectively enhance the mechanical robustness of the polymer network without losing the dynamic properties.Compared with SPN,the dually cross-linked network(DPN)demonstrates superior breaking strength,Young’s modulus,puncture force and toughness,underscoring its superior robustness.Furthermore,the cyclic tensile tests reveal that the energy dissipation capacity of DPN rivals,and in some cases surpasses,that of SPN,owing to the efficient energy dissipation pathway facilitated by[2]rotaxane.In addition,benefiting from stable topological structure of[2]rotaxane,DPN exhibits accelerated recovery from deformation,indicating superior elasticity compared to SPN.This strategy elevates the performance of SPNs across multiple metrics,presenting a promising avenue for the development of high-performance dynamic materials.

Supramolecular Polymer Networks with Enhanced Mechanical Properties:The Marriage of Covalent Polymer and Metallacycle

Main observation and conclusion Supramolecular polymer networks(SPNs)have always been the focus of research due to their novel features of good processability,stimuli-responsiveness,self-healing,and recyclability.Herein,we report the preparation of a metallacycle-linked supramolecular gel via orthogonal metal-ligand interactions and host-guest interactions.A triangular metallacycle with three appended 21-crown-7(21C7)units was obtained by the metal coordination of nickel(II)-salen-based dipyridyl ligands and platinum(II)acceptors.The integration of this metallacycle and traditional copolymer bearing secondary ammonium salts constructed a SPN via host-guest recognition between 21C7 units and ammonium salts,and a supramolecular gel further formed at high concentration.Multiple stimulus responsiveness and self-healing properties of gel were observed.The gel exhibited better stretchability compared to relative gel formed by copolymer alone owing to the synergistic effect of covalent bonds and supramolecular interactions.Moreover,compared to the model gel without metallacycles,the gel showed higher storage and loss moduli,and exhibited stronger stiffness in the self-healing tests performed with rheometer,indicating the metallacycle played an important role in improving the stiffness and self-healing of the gel.Therefore,the feasible approach to the formation of SPNs by the marriage of covalent polymers and metallacycles is expected to open a new way to design novel SPNs.

Multistimuli responsive supramolecular polymer networks via host-guest complexation of pillararene-containing polymers and sulfonium salts

A stimuli-responsive supramolecular polymer network has been constructed based on the host-guest interactions between the copolymer poly-P[5]A with pendent pillararene units and bis(sulfonium)diction guest G2.The formation mechanism of the supramolecular polymer network has been explored by the intensive study.With the addition of the competitive molecules and heating,the supramolecular polymer network could be dissociated and lead to clear changes in NMR spectroscopy and viscosity property.

Mechanically robust and dynamic supramolecular polymer networks enabled by[an]daisy chain backbones

Supramolecular polymer networks(SPNs)have garnered significant research interest due to their dynamic properties.However,while current developments primarily focus on managing supramolecular crosslinks,the role of polymer backbones—equally crucial to SPN properties—has not yet been sufficiently explored.Herein,we utilize mechanically interlocked[an]daisy chain as backbone to prepare a class of SPNs,where the force-induced motion of successive mechanical bonds toughens and reinforces the networks.In specific,the[an]daisy chain backbones connect with polynorbornene chains through quadruple H-bonding in the SPN networks.Compared to the control with non-slidable backbone,The representative SPN-2 exhibits a robust feature in tensile tests with high maximum stress(14.7 vs.7.89 MPa)and toughness(83.8 vs.48.6 MJ/m^(3)).Moreover,it also has superior performance in energy dissipation benefitting from the[an]daisy chain backbones as well as supramolecular crosslinks.Additionally,the SPN-2 displayed exceptional self-healing and reprocessing capabilities due to their dynamic quadrable H-bonding crosslinkers.These findings demonstrate the untapped potential of[an]daisy chain as a polymer skeleton to develop SPNs and open the door to design mechanically robust supramolecular materials with diverse smart functions.