The syntheses of triblock copolymers by the atom transfer radical polymerization of tert-butyl and iso-butyl acrylates as inner blocks with cyclohexyl methacrylate as outer blocks are reported. The living behavior and blocking efficiency of these polymerizations were investigated in each case. The use of difunctional macroinitiators led to ABA triblock copolymers with narrow polydispersities and controlled number-average molecular weights. These copolymers were prepared from bromo-terminated macroinitiators of poly(tert-butyl acrylate) and poly(iso-butyl acrylate), with copper chloride/N,N,N',N",N"-pentamethyldiethylenetriamine as the catalytic system, at 40 degrees C in 50% (v/v) toluene solutions. The block copolymers were characterized with size exclusion chromatography and H-1 NMR spectroscopy. Differential scanning calorimetry measurements were performed to reveal the phase segregation. The glass transition of the inner block was not clearly detected, with the exception of the copolymer synthesized with the longest poly(iso-butyl acrylate) macroinitiator length. (c) 2005 Wiley Periodicals, Inc.