Particle size distribution of WPU dispersions was tested by using particle size analyzer (Zetasizer Nano S90). The viscosities of WPU dispersions were measured on NDJ-8S digital readout viscometer at 25 °C with a rotate speed of 30 rpm. Morphology of WPU dispersion particles were characterized by Transmission electron microscopy (JOEL,Peabody, MA, USA) operating at an accelerating voltage of 200 kV. The WPU dispersions were diluted to a concentration of 1 wt% and were drop on a copper mesh for TEM observation. Fourier trans-form infrared (FTIR) spectra of the coatings were performed on a NEXUS 670 spectrophotometer (Thermo Fisher Scientific, USA) in transmission mode. Atom force microscopy (AFM) was performed on the surface of the coatings with a scanning area of 5 μm × 5 μm using the SPA-400 Atomic force microscope (Seiko Instruments Inc. Japan) in tapping mode. Roughness analysis was carried out using NanoScope-Analysis software. To measure swelling in water, dried coatings (weight designated as m0) was immersed in water for 70 min at 25 °C, the weight of the samples were measured (mi) at certain time interval. Swelling ratio was measured by the equation of Swelling ratio (%) = (mi- m0)/m0×100%. Thermogravimetric analysis (TGA) was carried out in TG 209 F1 differential thermogravimetric analyzer (NETZSCH Instruments, Germany) at a heating rate of 10 °C /min from 100 °C to 550 °C under nitrogen atmosphere. Dynamic viscoelastic behaviors of samples (5 × 10 mm) were investigated using DMA 242 C analyzer (NETZSCH Instruments, Germany) from -100 °C to 150 °C with a heating rate 5 °C /min at 1 Hz. Mechanical properties of coatings with a size of 5 × 25 mm was measured using tensile testing machine (GT-AI-7000S) with elongation rate of 100 mm/min under ambient conditions. The mechanical properties of finished leather (5 × 15 mm) were also investigated with elongation rate of 50 mm/min. The surface structure and cross section of finished leather samples were characterized by JEOL-6490 SEM. Samples were sprayed gold for testing. Water contact angle on leather samples were evaluated using the OCAH200 high-speed video contact angle measurer (DataPhysics Instruments GmbH Ger, Filderstadt, Germany).