5Carbon dioxide based oligo(carbonate-ether) diol (CO 2 -polyol) with both carbonate units and ether units in one polymer chain were prepared from copolymerization of CO 2 and propylene oxide (PO) using zinccobalt double metal complex as catalyst, and used to prepare CO 2 based waterborne polyurethane (CO 2 -WPU). The carbonate units in CO 2 -polyol improved the mechanical and oxidation resistance properties of CO 2 -WPU, while the ether units in CO 2 -polyol enhanced the hydrolysis resistance of CO 2 -WPU. The 10 tensile strength of CO 2 -WPU didn't show obvious drop during immersion in 0.25% sodium hydroxide solution, whereas that of oligoesterol based WPU dropped over 50% after 300 min, and lost mechanical property after 520 min immersion. Meanwhile, the retention of tensile strength of CO 2 -WPU was Ca.72% even after 46 h immersion in 6 wt% H 2 O 2 solution, while that was only Ca.32% for oligoetherol based WPU. Moreover, the thermal-mechanical performance of CO 2 -WPU film can be conveniently adjusted by 15 carbonate unit content (CU%) in CO 2 -polyol, i.e., when CU% in CO 2 -polyol increased from 30% to 66%, the glass transition temperature (T g ) increased from -7.8 0 C to 18.8 0 C, accompanied by an increase of tensile strength from 35.6 MPa to 52.2 MPa, a decrease of elongation at break from 630% to 410%. This work suggests that the CO 2 -WPU may be promising alternative for conventional WPU whose oligoetherol and oligoesterol were from fossil resources, and its comprehensive hydrolysis/oxidation 20 resistance may be a bonus unavailable from common oligomerol based WPU. 65 75%. 13 Recently, there is a nice report from Bardow that CO 2polyol may be viable alternative in polyurethane industry from an environmental point of view based on life cycle assessment. 14 We are wondering whether polyol derived from CO 2 and PO is suitable oligomerol for WPU. Up to now, however, there is few 70 reports on such issue.

Controllable synthesis of a narrow polydispersity oligo(carbonate-ether) tetraol provided a new relationship between the acidity (pKa1 value) of the chain transfer agent and the catalytic mechanism in the initial stage.