Poly(2-oxazoline) molecular brushes by grafting through of poly(2-oxazoline)methacrylates with aqueous ATRP

Molecular brushes of poly(2-oxazoline)s (POx) are an intriguing class of polymers as they combine a unique architecture with the properties of POx as a biomaterial. Here, the synthesis of several POx macromonomers with methacrylate end groups and consecutive grafting through polymerization by aqueous atom transfer radical polymerization (ATRP) at room temperature is reported. H-1-NMR spectroscopy and size exclusion chromatography (SEC) confirmed the synthesis of POx molecular brushes with maximum side chain grafting densities, narrow molar mass distributions (D <= 1.16) and final molar masses corresponding to the initial macromonomer : initiator ratio. Chain extension experiments show high end group fidelity and formation of block copolymer molecular brushes, and kinetic studies revealed a polymerization behavior of oligo(2-methyl-2-oxazoline) methacrylate very similar to the frequently used oligo (ethylene glycol) methacrylate (OEGMA(475)). Aqueous solutions of POx molecular brushes with poly( 2-ethyl- and 2-isopropyl-2-oxazoline) side chains exhibit the typically defined thermoresponsive behavior with a tunable, very narrow and reversible phase transition.