Poly(methyl methacrylate)-block-polyurethane-block-poly(methyl methacrylate) tri-block copolymers have been synthesized successfully through atom transfer radical polymerization of methyl methacrylate using telechelic bromo-terminated polyurethane/CuBr/N,N,N,N",N"-pentamethyldiethylenetriamine initiating system. As the time increases, the number-average molecular weight increases linearly from 6400 to 37,000. This shows that the poly methyl methacrylate blocks were attached to polyurethane block. As the polymerization time increases, both conversion and molecular weight increased and the molecular weight increases linearly with increasing con-version. These results indicate that the formation of the triblock copolymers was through atom transfer radical polymerization mechanism. Proton nuclear magnetic resonance spectral results of the triblock copolymers show that the molar ratio between polyurethane and poly (methyl methacrylate) blocks is in the range of 1 : 16.3 to 1 : 449.4. Differential scanning calorimetry results show T, of the soft segment at -35 degrees C and T-g of the hard segment at 75 degrees C. (c) 2008 Wiley Periodicals, Inc.