Poly(trimethylene carbonate)-bloek-poly(ethylene glycol)-block-poly(trimethylene carbonate) (PTMC-PEG-PTMC) triblock copolymers were synthesized successfully by the microwave-assisted ring-opening copolymerization of trimethylene carbonate (TMC) and poly(ethylene glycol) (PEG). The polymerizations were carried out in a single-mode microwave oven in the absence of any metallic compound catalyst. In the presence of PEG600, PTMC-PEG-PTMC triblock copolymer with a number-average molar mass of 16,600 g/mol and a TMC conversion of 97% could be synthesized after the TMC/PEG600 reaction mixture was irradiated at 120 C for 60 min. Both the molar mass of the resulting triblock copolymer and TMC conversion produced by the microwave method were higher than those produced by the conventional method. Thermal properties of the resulting polymers were studied by differential scanning calorimetry. (c) 2007 Elsevier Ltd. All rights reserved.