An AB 2 -Type Supramolecular Hyperbranched Polymer Based on Pillar[5]arene Host-Guest Recognition: Construction and Its pH-Responsiveness.

Supramolecular hyperbranched polymers not only possess the polymeric properties of hyperbranched polymers but also obtain additional stimuli-responsiveness due to the dynamic properties of non-covalent interactions. Herein, a novel supramolecular hyperbranched polymer constructed by an AB2 -type copillar[5]arene is reported. NMR spectroscopy, scanning electron microscopy, and viscosity experiments are utilized to characterize the self-aggregate process of the AB2 monomers. Interestingly, the supramolecular hyperbranched polymer exhibits pH-responsiveness. After protonation of the AB2 monomers by trifluoroacetic acid, the binding ability among the monomers becomes stronger, leading to the formation of supramolecular hyperbranched polymers with viscosity change. Additionally, although no conventional chromophores are doped, the supramolecular hyperbranched polymer shows a blue emission under irradiation. The fluorescence can be quenched upon addition of trifluoroacetic acid. This study enriches the field of supramolecular polymers with new building blocks and architectures and provided a new effective method for the fabrication of smart polymer materials with stimuli-responsiveness and special functions.