Recently, architectures where the individual polymer blocks are connected through supramolecular interactions such as hydrogen bonding, metal–ligand and pseudorotaxane like interactions have received significant attention. The inherent features of the molecular recognition-driven self-assembly confer significant advantages over their covalently linked brethren in terms of facilitating modularity and self-healing properties. Moreover, through careful design smart polymeric systems have been developed with stimuli-responsive structures and properties. Here, we report the successful engineering of new multi-stimuli responsive and coloured macromolecular assemblies based on well-defined functionalized polymer building blocks incorporating both electro-deficient cyclobis(paraquat-p-phenylene) (CBPQT4+) and electron-rich units (tetrathiafulvalene, naphthalene) moieties.The architectures of these materials have been constructed by holding together complementary well-defined polymer building blocks featuring either host or guest motifs attached in specific locations on polymer backbones. The inherent reversibility of supramolecular architectures has allowed “on demand” modular and tunable modification of structures and properties of materials. More particularly, we have exploited the presence of coloured CBPQT4+ based interactions i) to create (re)programmable supramolecular temperature and pH sensors showing a thermal memory function, i) to control the swelling/shrinking processes of hydrogels by applying different stimuli (T, V, competitive macromolecules) and to impart both thermal and temporary memory function to the mats, and iii) to develop polymeric hydrogel systems capable of swelling via a supramolecular transmission. An important practical aspect of these new functional materials is that all relevant phenomena (self-assembly and disassembly processes, reading/reprogramming of temperature, memory function) have an associated visible readout, thereby affording convenient and quantifiable systems with applications spanning the physical and biological sciences.

Host-guest chemistry for the elaboration of multi-stimuli “colourful” polymeric materials

ACS Spring Meeting 2021

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