Intelligent CO2- and photo-dual-responsive polymer vesicles with tunable wall thickness

Abstract

Intelligent CO₂- and photo-dual-responsive polymer vesicles with tunable wall thickness were fabricated by the combination of RAFT polymerization and a self-assembly strategy. The polymer vesicles were composed of hydrophobic poly(methyl methacrylate) (PMMA) chains with pendant anthracene units and poly((2-diethylamino)ethyl methacrylate) (PDEAEMA) chains, while PDEAEMA chains can be partly charged upon CO₂ bubbling. The wall thickness of vesicles increased with the hydrophobic chain length. With the aeration of CO₂, the large sized vesicles transformed to small aggregates by tuning the protonation degree of PDEAEMA chains. In contrast, the protonation of PDEAEMA chains could be reverted by heating. The aeration time of CO₂ has an essential influence on the self-assembly deformation of block copolymers. Furthermore, the vesicular shell can be photocrosslinked by the photodimerization of anthracene upon 365 nm UV light irradiation and dissociated by photochemical dissociation upon 254 nm UV light irradiation. The vesicles were further used as a potential “smart” platform for drug release, and displayed controlled drug-release characteristics upon all of the various pH buffer solutions, CO₂ bubbling times and UV light irradiation duration.