Thermo- and pH-responsive star-like polymers synthesized by photoATRP

Abstract The thermo and pH-responsive star-like block copolymers are synthesized with controlled molecular weight and low dispersity via photoinduced atom transfer radical polymerization (photoATRP) using a low ppm level of CuBr2/tris[2-(dimethylamino)ethyl]amine (Me6TREN) complex. The star-like polymers PAA-b-P(MEA-co-OEGA480) exhibit both a lower critical solution temperature (LCST) transition in water and the upper critical solution temperature (UCST) transition in ethanol. The UCST decreases with the increase of the POEGA proportion of side chains in the star-like block copolymers, while the LCST increases with the increase of pH in water. The prepared star-like block copolymers have excellent biocompatibility, mild phase transition temperature, and the adjustable LCST with pH in the range of organisms. These polymers could be potentially used in pH-responsive and thermosensitive applications and used as nanoreactors to confine the growth of inorganic nanoparticles.