Synthesis of double hydrophilic graft copolymer containing poly(ethylene glycol) and poly(methacrylic acid) side chains via successive ATRP

A well-defined double hydrophilic graft copolymer, with polyacrylate as backbone, hydrophilic poly(ethylene glycol) and poly(methacrylic acid) as side chains, was synthesized via successive atom transfer radical polymerization followed by the selective hydrolysis of poly(methoxymethyl methacrylate) side chains. The grafting-through strategy was first used to prepare poly[poly(ethylene glycol) methyl ether acrylate] comb copolymer. The obtained comb copolymer was transformed into macroinitiator by reacting with lithium diisopropylamine and 2-bromopropionyl chloride. Afterwards, grafting-from route was employed for the synthesis of poly[poly(ethylene glycol) methyl ether acrylatel-g-poly(methoxymethyl methacrylate) amphiphilic graft copolymer. The molecular weight distribution of this amphiphilic graft copolymer was narrow. Poly(methoxymethyl methacrylate) side chains were connected to polyacrylate backbone through stable C-C bonds instead of ester connections. The final product, poly[poly(ethylene glycol) methyl ether acrylatel-g-poly(methacrylate acid), was obtained by selective hydrolysis of poly(methoxymethyl methaerylate) side chains under mild conditions without affecting the polyacrylate backbone. This double hydrophilic graft copolymer was found be stimuli-responsive to pH and ionic strength. (c) 2008 Wiley Periodicals, Inc.