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

Abstract

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.

A Pd2L4 Metallacage‐Cored Supramolecular Amphiphile and Its Application in Dual‐Responsive Controllable Release†

“…[ 28‐30 ] Unlike covalent‐bond based amphiphiles, supramolecular amphiphiles [ 31‐32 ] are constructed by noncovalent interactions including host–guest interactions, π–π stacking, metal coordination and hydrogen bonding. [ 33‐43 ] Compared with traditional amphiphiles, the advantage of supramolecular amphiphiles is that the functional groups can be combined under mild conditions, which can effectively avoid multiple complicated steps and purification processes in the synthesis of amphiphiles. [ 44‐45 ] More importantly, due to the dynamic and reversible nature of noncovalent interactions, self‐assembly systems constructed by supramolecular amphiphiles are tunable and exhibit responsiveness to external stimuli, [ 46‐48 ] making them of outstanding value in drug delivery, protein probes, nanodevices and other fields.…”

Phenylthiol-BODIPY-based supramolecular metallacycles for synergistic tumor chemo-photodynamic therapy

“…In recent decades, coordination-driven self-assembly has become a powerful tool for constructing supramolecular coordination complexes (SCCs) ( 20 – 25 ). Numerous discrete SCCs have been synthesized via the formation of metal-organic coordination bonds between electron-poor acceptors containing transition metals (Fe, Cu, Co, Zn, Pt, Pd, etc.)…”

Metallacycle-cored fluorescent supramolecular polymer networks for the detection of acidic environments

“…A supramolecular gel was also obtained upon increasing the concentration of the SP to 260 mg mL −1 . Owing to the decrease in the host–guest association constant caused by heating, 24 the corresponding host–guest interaction was weakened, and the formed gel underwent sol–gel transition at 50 °C (Fig. 4a).…”

“…Supramolecular coordination complexes (SCCs) can exhibit superior properties compared to independent building blocks due to the interactions between the building blocks and the unique cyclic topologies, thus providing a simple and efficient method for the bottom-up synthesis of functional materials at the molecular level. [19][20][21][22][23][24][25][26][27][28][29][30] SPs with novel topological structures can be thus prepared by the incorporation of SCCs. For example, an SP containing Pt(II) rhomboidal metallacycles with 21-crown-7 moieties via metal coordination interactions has been formed via the host-guest interaction between the crown ether on the metal ring and the ammonium salt.…”