A series of polycarbonate copolymers were synthesized by the ring-opening bulk polymerization of 2-phenyl-5,5-bis(hydroxymethyl) trimethylene carbonate (PTC) and 5,5-dimethyl trimethylene carbonate (DTC) with tin(II) 2-ethylhexanoate and aluminum isopropoxide as initiators. The copolymers obtained were characterized by H-1-NMR, Fourier transform infrared, and ultraviolet. The influence of the molar ratio of the monomers, the initiators, and their concentrations, the reaction time, and the reaction temperature on the copolymerization was also studied. The copolymerization of monomers DTC and PTC was a nonideal copolymerization, and the copolymerization reactivity ratio of the monomer DTC was higher than that of PTC in the copolymerization process. In vitro release profiles of fluorouracil from the copolymers showed that the copolymer had a steady drug-release rate and good controlled-release property. (C) 2007 Wiley Periodicals, Inc.