A series of triblock copolymers, containing a CO2-switchable block poly(2-(dimethylamino)ethyl methacrylate) (PDM) block
and two symmetrical hydrophilic blocks polyacrylamide (PAM), were synthesized using atom transfer radical polymerization (ATRP)
method. The pH and conductivity tests showed that the triblock copolymer exhibited switchable responsiveness to CO2, i.e. a relatively low
conductivity of solution could be switched on and off by bubbling and removing of CO2, and the triblock copolymer aqueous solution
displayed a CO2-switchable viscosity variation. The changes were all attributed to protonation of tertiary amine groups in PDM blocks and
proven by 1H-NMR. Cryogenic transmission electron microscopy and dynamic light scattering characterization demonstrated that the
viscosity variation was the result of a unilamellar vesicle-network aggregate structure transition. The release of rhodamine B from the
vesicles with and without CO2 stimuli showed the potential application in drug delivery domains; after CO2 bubbling, the drug release rate
could be accelerated. Finally, reasonable mechanism of CO2-switchable morphology changes and CO2-induced drug release was proposed.

EB00000002674K

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• CO2-sensitive Amphiphilic Triblock Copolymer Self-assembly Morphology Transition and Accelerating Drug Release from Polymeric Vesicle