Controlled polymerization of N-isopropylacrylamide (NIPAAM) was achieved by atom transfer radical polymerization (ATRP) using ethyl 2-chloropropionate (ECP) as initiator and CuCl/tris(2-dimethylaminoethyl)-amine (Me6TREN) as a catalytic system. The polymerization was carried out in DMF:water 50:50 (v/v) mixed solvent at 20degreesC. The first order kinetic plot was linear up to 92% conversion. Controlled molecular weights up to 2.2 x 10(4) and low polydispersities (1.19) were obtained. The living character of the polymerization was also demonstrated by self-blocking experiments. Block copolymers with N,N-dimethylacrylamide (DMAAM) and 3-sulfopropyl methacrylate (SPMA) were successfully prepared.