Shape Memory Supramolecular Polymer Gels Constructed by Pillar[5]arene-Based Mechanically Interlocked Polymer Networks

Mechanically interlocked networks are cross-linked by mechanically interlocked polymers, whose dynamic mechanical bonding provides a solid foundation for their application in materials science. Noncovalent interactions are indispensable linkages for building supramolecular polymers but exhibit low mechanical strength. Therefore, in this paper, we have designed and synthesized a class of mechanically interlocked supramolecular polymer networks (MISPNs) with shape memory behavior, using which we have prepared gel materials with solvent-responsive shape memory behavior and reversible light transmittance changes in response to noncovalent interactions. It was found that the naphthalene-functionalized pillar[5]arene (compound 3) served as the backbone of the MISPNs, and its mechanically interlocked topology not only ensured good stability of the polymer networks but also endowed the shape memory properties of the shape memory materials. Meanwhile, the abundant oxygen (O) and sulfur (S) atoms in the polymer networks form multiple hydrogen bonds with the H atoms in the protonated solvent, which contributes to the shape memory behavior and the reversible light transmission behavior of the gel materials. The herein reported MISPNsgel materials offer a possible strategy for the development of multifunctional materials with good mechanical properties, sensitive stimulus response properties, and excellent smart information protection properties.