Soft segmental effect of methylene bis(p-cyclohexyl isocyanate) based thermoplastic polyurethane impregnated with lithium perchlorate/propylene carbonate on ionic conductivity

Thermoplastic polyurethane (TPU) was employed as the polymer matrix for ion conduction as gelled electrolytes with lithium perchlorate (LiClO4) in pro pylene carbonate (PC) solution. The TPU was prepared by methylene bis(p-cyc lohexyl isocyanate) as the hard segment while employing both poly(ethylene glycol) (PEG) and poly(tetramethylene glycol) (PTMG) as the soft segments. The copolymer comprising both PEG and PTMG was prepared such that it posses sed the combined characteristics of good conductivity from the former and g ood mechanical properties from the latter. All the polymers were characteri zed by gel permeation chromatography, differential scanning calorimetry, an d Fourier transform IR spectroscopy. The conductivity data were obtained fr om alternating current impedance experiments. The results revealed that the copolymer containing both PEG and PTMG as the soft segments showed better performance than TPU containing either PEG or PTMG. The copolymer TPU(PEG/P TMG) proved to be a good gelled electrolyte from 5 to 85 degreesC. This cop olymer, impregnated with 150% LiClO4/PC, possessed good mechanical strength and conductivity as high as 10(-3) S/cm. (C) 2001 John Wiley & Sons, Inc.