Spectroscopic investigations of poly(oxypropylene)glycol-based waterborne polyurethane doped with lithium perchlorate

Polyaddition of isophorone diisocyanate to poly(oxypropylene)glycol (PPG)-Based waterborne polyurethane (WPU) synthesized by a modified acetone process was performed. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and impedance spectroscopy (IS) were utilized to monitor the phase change of this WPU with the doped lithium perchlorate (LiClO4) concentration. Significant changes occur in the FTIR spectrum of the WPU with the added salt concentration above 1 mmol/g WPU, indicating that an interaction with the lithium cation within the hard segment and between the hard and soft phases occurs. The soft segment T-g increases with increasing LiClO4 through the examination of DSC. XPS results reveal that the component of nitrogen polaron sites (Ni) increases with increasing LiClO4 and that the saturation level of salt doping is evidenced by the mole ratio of component C-O to C=O; meanwhile, a rearrangement in the long chain of the soft domain has also been observed when this WPU is doped with LiClO4. IS results indicate an increase in bulk conductivity as the salt concentration is increased.