Preparation of poly(oligo(ethylene glycol) monomethyl ether methacrylate) by homogeneous aqueous AGET ATRP

A new convenient initiation process for ATRP, activators generated by electron transfer (AGET ATRP), was investigated in homogeneous aqueous solution at ambient temperature (30 degrees C). Tris[(2-pyridyl)methyl]amine (TPMA)/CuBr2 complex was used as an oxidatively stable Cu(II) precursor. Ascorbic acid was used as a reducing agent to reduce the air-stable Cu(II) complex, resulting in generation of an active catalyst. Two oligo(ethylene glycol) monomethyl ether methacrylates (OEOMA) with different pendent CEO chain lengths (OEOMA300 and OEOMA475) were used to demonstrate the broad applicability of aqueous AGET ATRP for the synthesis of well-controlled water-soluble homopolymers and random copolymers at the targeting degree of polymerization (DP) = 300. Concentrations of Cu(II) complex and ascorbic acid as well as ratio of water to macromonomer were varied to produce well-controlled homopolymers of P(OEOMA300) and P(OEOMA475) as well as random copolymer P(OEOMA300-ran-OEOMA474) with DP > 240 and M-w/M-n < 1.3. CuCl2/TPMA complex resulted in a slower but better controlled polymerization than CuBr2/TPMA complex. The CuBr2/bpy complex produced polymers with broader molecular weight distribution than the CuBr2/TPMA complex. Aqueous AGET ATRP retains all of the benefits of normal ATRP. Additionally, it provides a facile route for the preparation of polymers due to the use of oxidatively stable catalyst precursors.