CONDUCTIVITY AND MORPHOLOGICAL-STUDIES OF TPU-NH4CF3SO3 POLYMERIC ELECTROLYTES

NH4CF3SO3 has been used to dope thermoplastic polyurethane (TPU) with soft segments (SS) of poly(tetramethylene glycol) (PTMG) and poly(prop ylene glycol) (PPG), each having a SS molecular weight (M(W)) = 1000 g /mol. The PTMG-based TPU was examined at salt concentrations from 0.15 to 2.00 mmol/g of TPU at a constant hard segment (HS) concentration o f 20%. The PPG-based TPUs of HS concentrations varying from 20% to 50% were doped at a single salt concentration of 0.67 mmol/g of TPU. Alth ough room temperature ionic conductivities are low (similar to 1 x 10( -8) S/cm), these systems can be used to elucidate the relationship bet ween structure and morphology and between structure and ionic conducti vity. In the PPG-based TPU/NH4CF3SO3 system, in which the conductivity follows a VTF form as a function of temperature, the salt is dissocia ted and ionic conductivity at 100 degrees C is similar to 1 x 10(-5) S /cm. However, in the PTMG-based TPU/NH4CF3SO3 system, in which the con ductivity temperature behavior is Arrhenius at low temperatures and VT F at higher temperatures, the salt is not completely dissociated, and conductivity at 100 degrees C is about 1.5 x 10(-7) S/cm. Phenomenolog ical and effective medium theories have been used to fit the experimen tal conductivity data with good agreement.