Hierarchical Assembly of Amphiphilic POSS-Cyclodextrin Molecules and Azobenzene End-Capped Polymers

Stimuli-responsive polymers have been widely studied because of their potential use in nanocarriers and nanocontainers. In this study, a smart multistimuli responsive system was prepared through a light controlled supramolecular assembly. Mono cyclodextrin substituted isobutyl polyhedral oligomeric silsesquioxane (mCPOSS), an amphiphilic molecule, was synthesized by copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC), while azobenzene end-capped poly(ethylene glycol)-b-poly(2-(dimethylamino)ethyl methacrylate) copolymer (PEG-b-PDMAEMA-azo, PPA), a biocompatible pH/temperature-responsive macromolecule, was synthesized by atom transfer radical polymerization and CuAAC. The self-assembly process of PPA and mCPOSS in aqueous solution was as followed: first, mCPOSS self-assembled into a nanosphere in aqueous solution because of its amphipathic property; then, the trans-azo end groups of the PPA interacted with the cyclodextrin cavities on the nanosphere, and complex micelles were formed by the supramolecular assembly between PPA and mCPOSS. In addition, the morphology of the micelles could be adjusted by the ratio of PPA and mCPOSS, the formation and the dissociation of the micelles could be controlled by visible and ultraviolet light, and the size of the micelles could be tuned by pH.