Synthesis of well-defined pH-responsive PPEGMEA-g -P2VP double hydrophilic graft copolymer via sequential SET-LRP and ATRP

Abstract

A series of well-defined double hydrophilic graft copolymers containing poly(poly(ethylene glycol) methyl ether acrylate) (PPEGMEA) backbone and poly(2-vinylpyridine) (P2VP) side chains were synthesized by successive single electron transfer living radical polymerization (SET-LRP) and atom transfer radical polymerization (ATRP). The backbone was first prepared by SET-LRP of poly(ethylene glycol) methyl ether acrylate (PEGMEA) macromonomer using CuBr/tris(2-(dimethylamino)ethyl)amine as catalytic system. The obtained homopolymer then reacted with lithium diisopropylamide and 2-chloropropionyl chloride at −78 °C to afford PPEGMEA-Cl macroinitiator. poly(poly(ethylene glycol) methyl ether acrylate)-g-poly(2-vinylpyridine) double hydrophilic graft copolymers were finally synthesized by. ATRP of 2-vinylpyridine initiated by PPEGMEA-Cl macroinitiator at 25 °C using CuCl/hexamethyldiethylenetriamine as catalytic system via the grafting- from strategy. The molecular weights of both the backbone and the side chains were controllable and the molecular weight distributions kept relatively narrow (Mw/Mn ≤ 1.40). pH-Responsive micellization behavior was investigated by 1H NMR, dynamic light scattering, and transmission electron microscopy and this kind of double hydrophilic graft copolymer aggregated to form micelles with P2VP-core while pH of the aqueous solution was above 5.0. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011