Novel biodegradable poly(carbonate-ether)s (PCEs) with lower critical solution temperature (LCST) at body temperature were synthesized by copolymerization of CO2 and ethylene oxide (EO) under double metal cyanide (DMC) catalyst. The PCEs showed carbonate unit (CU) content of 1.042.4 mol % and molecular weight of 2.7247 kg/mol, which exhibited reversible thermoresponsive feature in deionized water with LCST in a broad window from 21.5 to 84.1 degrees C. The LCST was highly sensitive to the CU content and the molecular weight of PCEs, and it showed a linear relation with CU content for PCEs with similar molecular weight. In particular, aqueous solution of PCE with a 26.0 mol % of CU showed an LCST around 36.1 degrees C, which was very close to the body temperature. Interestingly, it was found that the phase transition behavior changed with PCE concentration. For PCE with Mn of 2.7 kg/mol and CU content of 30.0 mol %, the LCST increased from 21.5 to 36.7 degrees C when the PCE concentration changed from 10 to 1 g/L. Dynamic light scattering indicated that the phase transition was possibly due to a coil-to-globule transition. The thermoresponsive biodegradable PCE with LCST at body temperature is promising for biomedical applications, especially for in vivo applications. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013