Thermoresponsive catechol end-functionalized polymers/CBPQT4+, 4Cl- supramolecular assembly

In the past decade, the adhesive properties of catechol derivatives have inspired researchers for the design of various macromolecular architectures featuring fascinating properties and finding applications in energy storage, coatings, adhesives and biomaterials. In this work, the complexation of catechol end-functionalized polymers prepared by RAFT polymerization was investigated in aqueous media with the electron-deficient tetracationic cyclophane cyclobis(paraquat-p-phenylene) (CBPQT(4+)) by using UV-Vis and H-1 NMR experiments. The formation of pseudorotaxanes between the catechol end-functionalized polymers and the CBPQT(4+),4Cl(-) leads to the formation of colored guest-specific complexes displaying tunable complexation properties. In particular, we demonstrated that the thermo-responsiveness i.e. the lower critical solution temperature (LCST) of the catechol end-functionalized poly(NIPAM) could be used as a simple and convenient tool to disrupt the complexation with CBPQT(4+); 4Cl(-) resulting in the disappearance of the characteristic color of the Catechol/BB complex while releasing the cyclophane in the aqueous solution. Furthermore, these supramolecular host/guest assemblies could be disrupted, on demand, by the addition of a competitive Naphthalene derivative leading to the appearance of the characteristic purple color of Naphthalene/CBPQT(4+) complexes. These results pave the way for the design of a new generation of stimuli responsive materials with control properties.