Triple stimuli-responsive supramolecular assemblies based on host-guest inclusion complexation between β-cyclodextrin and azobenzene

The host polymer beta-cyclodextrin-poly[(2-(2-methoxyethoxy)ethylmethacrylate)-co-oligo(ethylene glycol) methacrylate] [beta-CD-P(MEO(2)MA-co-OEGMA)] was prepared by click chemistry and atom transfer radical polymerization (ATRP), and the guest polymer poly(e-caprolactone)SS-poly(ethylene glycol) with azobenzene (Azo) group at one end (Azo-PCL-SS-PEG) was synthesized by the combination of ring-opening polymerization (ROP) and esterification reaction. Based on the inclusion complexation between beta-CD and Azo groups, the supramolecular polymer beta-CD-P(MEO(2)MA-co-OEGMA)/Azo-PCL-SS-PEG was successfully obtained. Benefitting from the amphiphilicity, the supramolecular polymer could self-assemble into spherical micelles in aqueous solution, and the supramolecular micelles presented obvious UV light-, thermo- and redox-responsive properties. Alternating irradiation of the solution with UV or visible light could induce the reversible supramolecular self-assembly and disassembly of the micelles. When the temperature of the solution increased above the lower critical solution temperature (LCST) of P (MEO(2)MA-co-OEGMA) chains, the micelles became smaller and aggregated with each other. Moreover, after adding DTT into the micellar solution, the spherical micelles changed into irregular aggregates.