A series of triblock copolymers, containing a CO_2-switchable block poly（2-（dimethylamino）ethyl methacrylate）（PDM） block and two symmetrical hydrophilic blocks polyacrylamide（PAM）, were synthesized using atom ...A series of triblock copolymers, containing a CO_2-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 p H and conductivity tests showed that the triblock copolymer exhibited switchable responsiveness to CO_2, i.e. a relatively low conductivity of solution could be switched on and off by bubbling and removing of CO_2, and the triblock copolymer aqueous solution displayed a CO_2-switchable viscosity variation. The changes were all attributed to protonation of tertiary amine groups in PDM blocks and proven by 1 H-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 CO_2 stimuli showed the potential application in drug delivery domains; after CO_2 bubbling, the drug release rate could be accelerated. Finally, reasonable mechanism of CO_2-switchable morphology changes and CO_2-induced drug release was proposed.展开更多
基金financially supported by Scientific Research Innovation Team Project of Provincial Universities in Sichuan Province (No. 13TD0025)
文摘A series of triblock copolymers, containing a CO_2-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 p H and conductivity tests showed that the triblock copolymer exhibited switchable responsiveness to CO_2, i.e. a relatively low conductivity of solution could be switched on and off by bubbling and removing of CO_2, and the triblock copolymer aqueous solution displayed a CO_2-switchable viscosity variation. The changes were all attributed to protonation of tertiary amine groups in PDM blocks and proven by 1 H-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 CO_2 stimuli showed the potential application in drug delivery domains; after CO_2 bubbling, the drug release rate could be accelerated. Finally, reasonable mechanism of CO_2-switchable morphology changes and CO_2-induced drug release was proposed.
