Salt‐Induced Micelle Behavior of Poly(sodium acrylate)‐block‐Poly(N‐isopropylacrylamide) by ATRP

Temperature‐ and pH‐sensitive diblock copolymers PAANa75‐b‐PNIPAMm are prepared by a combination of reverse and normal ATRP in aqueous solution at room temperature. The block copolymer is also stimuli‐sensitive with respect to salt in the aqueous solution, and forms spherical star‐like micelles with a PNIPAM core and an expanded PAANa shell for PAANa75‐b‐PNIPAM76 as well as spherical crew‐out micelles with a PNIPAM core for PAANa75‐b‐PNIPAM5110, as indicated by a fluorescence probe technique and TEM. A three‐stage model mechanism of phase transition driven by small molecule salt is proposed. magnified image