CO2-triggered fast micellization of a liposoluble star copolymer in water

This study reports a green and efficient strategy using CO2 to trigger fast micellization of a liposoluble star copolymer in water. The star copolymers consisting of a hyperbranched polyethylene (HBPE) core and multiple poly(2( dimethylamino) ethyl methacrylate) (PDMAEMA) arms were synthesized through a sequential Pd-catalyzed chain walking copolymerization of ethylene and 2-(2-bromoisobutyryloxy) ethyl acrylate followed by an atom-transfer radical polymerization of DMAEMA. The star copolymers with large HBPE cores and low PDMAEMA arm numbers or short arms can be easily dissolved in aliphatic hydrocarbon solvents. The copolymers could be quickly dispersed in water and form micelles after CO2 bubbling. A N-2-mediated switching process following the CO2 treatment is shown to reverse the micelles back to their neutral state without causing additional micelle aggregation. The CO2 switchability of PDMAEMA prompted fast micellization of such liposoluble star copolymers. This article contains supporting information that will be made available online once the issue is published.