Poly(tert-butyl methacrylate) macrointermediates (PtBMABr) with a bromine atom end group were synthesized in the presence of the single ligand N,N,N',NN'',N''-pentamethyldiethylenetriamine (PMDETA) by atom transfer radical polymerization (ATRP) in bulk. A macromonomer was successfully prepared by the nucleophilic substitution of the chain end to attain a high efficiency of C=C incorporation (89-92%; H-1 NMR). The macromonomer molecular weight was controlled to result in a high molecular weight (11000) with a narrow distribution of 1.20.