Stimuli-induced multiple dissociation and micellization transitions of random copolymers
RSC Advances (2015), 5(81), 65847-65855.
Li Shasha, Chen Guangxin, Zhou Zheng, Li Qifang
Abstract: A novel thermo- and light-responsive random copolymer poly(o-nitrobenzyl methacrylate)-co-2-(2-methoxyethoxy)ethyl methacrylate-co-oligo(ethylene glycol) methacrylate (P(NBMA-co-MEO2MA-co-OEGMA)) was synthesized by atom transfer radical polymn. (ATRP). This amphiphilic random copolymer self-assembled into spherical micelles with a PNBMA core and a PMEO2MA/POEGMA corona in aq. soln. Aggregates were formed when the temp. increased above the lower crit. temp. (LCST). Upon UV irradn., the transformation of hydrophobic PNBMA into hydrophilic poly(methacrylic acid) (PMAA) induced the disruption of the initial micelles and the release of the encapsulated fluorescent dye, Nile Red, into water. The accordingly obtained hydrophilic random copolymer P(MAA-co-MEO2MA-co-OEGMA) exhibited thermo- and pH-responsive behavior. Further increasing the temp. or decreasing the pH, P(MAA-co-MEO2MA-co-OEGMA) formed PMEO2MA/POEGMA-core or PMAA-core micelles with the re-encapsulation of Nile Red. This random copolymer has great potential in applications such as controlled release and selective encapsulation.
