Wherein the synthetic method of WPU as below shown: pickedthe stoichiometric amount of PPG into four-neck flask and kept itin oil bath at 85 ◦C equipped with a mechanical stirrer, and addition of the stoichiometric amount of TDI into flask to kept 1 h, thenadded DMPA into the flask to kept over 1.5 h, subsequently cooledthe temperature to 73 ◦Cand added EG into flask to kept another1 h; continuously decreased the temperature to room temperatureand added TEA with acetone into the flask to neutralize 10 min,subsequently added the deionized water into flask to dilute theemulsion 30 min, finally rise the temperature to 50 ◦Cwith the innerpressure 0.02 MPa in 30 min to remove acetone. Eventually, a WPUemulsion with 30% solid content was obtained. The WPU membranes formed in teflon vessel were used to measure the thermalconductivity values.