Synthesis of poly (2-ethyl-2-oxazoline)-b-poly(styrene) copolymers via a dual initiator route combining cationic ring-opening polymerization and atom transfer radical polymerization

摘要

Block copolymers of 2-ethyl-2-oxazoline (EtOx) and styrene were synthesized by a combination of cationic ring-opening polymerization (CROP) and atom transfer radical polymerization (ATRP). Initially, a detailed kinetic investigation for the alpha-bromoisobutyrylbromide (BrEBBr) initiated CROP of EtOx was performed in acetonitrile at different polymerization temperatures ranging from 100 to 180 degrees C under microwave irradiation. Poly(2-ethyl-2-oxazoline) (PEtOx) homopolymers with controlled molecular weights and narrow polydispersity indices were synthesized in short reaction times. Polymers with relatively high molar masses and low polydispersity indices (M-n,M-SEC = 48 500 g/mol, PDI = 1.29) could also be obtained. Following the synthesis of a PEtOx macroinitiator (M-n,M-SEC = 3700 g/mol, PDI = 1.09), the ATRP of styrene was performed with CuBr and tris[2-(dimethylamino)ethyl]amine (Me(6)Tren) as catalytic system. The micellization behavior of the obtained amphiphilic block copolymers was further investigated by dynamic light scattering (DLS) and atomic force microscopy (AFM).