Synthesis and self-assembly of ABC linear triblock copolymers to target CO2-responsive multicompartment micelles

Abstract

Multicompartment micelles (MCMs) have advantage in medical applications because of their capability of transporting and releasing two incompatible compounds at one time. However, the achievement of stimulus-responsive MCMs, which is a necessary condition for controlled delivery, is rarely assessed. In this study, a series of ABC linear triblock copolymers were synthesized by a stepwise RAFT polymerization method starting from a macromolecular chain transfer agent containing poly(ethylene oxide) and using monomers of 2,2,3,4,4,4-hexafluorobutyl methacrylate and 2-(diethylamino)ethyl methacrylate to construct other two segments. The block lengths were tailored in order to achieve hierarchical CO₂-responsive MCMs. A morphological transition from spheres to MCMs under stimulation of CO₂ is finally observed with two copolymers among this series. The volume fraction of each block in the triblock copolymer was calculated and then depicted in a ternary phase diagram, in which a narrow composition window for the CO₂-responsive MCMs was suggested. These findings will guide the future design and fabrication of MCMs.