Characteristics of PPG-based thermoplastic polyurethane doped with lithiumperchlorate

Segmented thermoplastic polyurethane (TPU) was synthesized from methylene b is(cyclohexyl isocyanate) (H12MDI), ethylenediamine (EDA), and poly(propyle ne glycol) (PPG) with a molecular weight of 1000. The ratio of hard segment to soft segment (NCO/OH) is changed to test the chemical and physical prop erties. Fourier transform infrared spectroscopy (FTIR), differential scanni ng calorimetry (DSC), and impedance spectroscopy (IS) were utilized to moni tor the phase change of these TPU samples with various lithium perchlorate (LiClO4) concentrations. Significant changes occur in the FTIR spectrum of the TPU with LiClO4, concentration above 0.5 mmol/g TPU, indicating that an interaction existed between the lithium cation and the hard segment or sof t phase. The soft-segment T-g. increased with increasing LiClO4, concentrat ion through the examination of DSC. IS results indicate an increase in bulk conductivity as the salt concentration is increased. Electrochemical stabi lity of the TPU sample was studied by cyclic votammetry (CV). (C) 2001 John Wiley & Sons, Inc.