CO_2-Breathing Polymer Assemblies via One-Pot Sequential RAFT Dispersion Polymerization

摘要

ABC triblock copolymer assemblies with reversible “breathing” behaviors based on polyoligo(ethylene glycol) methyl ether methacrylate-b-poly(benzyl methacrylate)-b-poly2-(diethylamino)ethyl methacrylate (POEGMA-b-PBnMA-b-PDEA) are fabricated via one-pot sequential reverisble additionfragmentation chain transfer dispersion polymerization. Using a POEGMA as the macromolecular chain transfer agent, chain extension with BnMA and DEA is conducted in ethanol, where PBnMA acts as the core-forming block, and the PDEA block endows the solvophilicity and CO_2-responsiveness. With the increment of the DP of PBnMA, the morphology of the assemblies evolves from spheres to worms, and to vesicles, while it degenerates from conglutinated vesicles to spheres as the DP of PDEA increases. After replacing ethanol with water, the morphologies of these assemblies remain unchanged, while their size decreases due to the collapse of the hydrophobic PDEA chains. Interestingly, due to the protonation and deprotonation of PDEA blocks, both the spheres and vesicles manifest a reversible expansion/shrinkage upon alternative CO2/Ar stimulation, exhibiting distinctive breathing feature.