Aliphatic polycarbonate (APC) macroinitiators bearing an alpha-haloester terminal group were successfully prepared by cobalt-catalyzed epoxide/carbon-dioxide copolymerization in the presence of alpha-halocarboxylic acids as chain transfer agents. The atom transfer radical polymerization of vinyl monomers, such as methyl methacrylate and styrene, from the obtained APC macroinitiators gave the corresponding APC-block-polyalkylene copolymers.