Thermoresponsive polymers and host-guest chemistry: a win-win combination
Abstract
The combination of heat-sensitivepolymers and supramolecular chemistry has recently led to the development of fascinating adaptive materials. In this context, most studies have focused on exploiting host-guest interactions to control the physicochemical properties of polymeric materials.1 This approach has notably enabled the creation of materials with programmable thermosensitivity and sensor properties.2 In contrast, the exploitation of polymer thermoresponsiveness to control the recognition properties of host-guest systems at the molecular level is much less developed, and a perfect understanding of the mechanisms triggering thermo-induced decomplexation or complexation is still elusive.
In this communication, we will illustrate through three studies how the host-guest chemistry and the thermo-induced phase separation mechanisms can “talk together” to synergistically tune the coil↔globule transition and the complexation state of polymeric systems. The first example3 concerns a comparative analysis of the behaviour of complexes formed from different naphthalene end-functionalized LCST or UCST polymers and the electron-deficient cyclobis(paraquat-p-phenylene) tetrachloride (CBPQT4+, 4Cl-)3 host when subjected to heat treatment. This study provided an understanding of the mechanisms triggering the thermo-induced (de)complexation of such complexes. The second study reports a supramolecular approach for developing an intelligent thermoresponsive polymeric hydrogel featuring a dual temperature and time memory function based on a kinetic control of the material's (de)complexation and (re) swelling behaviours. The last study illustrates how a thermo-induced phase separation mechanism can regulate on demand the Diels-alder reactivity of a synthetic self-complexing host-guest molecular switch CBPQT4+-Fu, consisting of an electron-rich furan unit covalently attached to the electron-deficient CBPQT4+host, with maleimide in water. Thanks to a supramolecular control over the topology of CBPQT4+-Fu combined with a thermoresponsive supramolecular regulator, we reported a rare example of decreased reactivity upon increasing temperature.
Origin | Files produced by the author(s) |
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