A range of sulfonated polyimides have been synthesised and characterised. These are cation conductors and have good stability at high temperature under anhydrous conditions. Potential for exploitation exists in a temperature range interfacing with the lower range of inorganic-based cation conductors.
New cation conducting polyamide films are now available with ion exchange capacity in the range 0.5 -1.5 mmolg-1. Room temperature dry state conductivity of the Na+ forms fall in the range 2.5 x 10-7 - 1 x 10-5 S cm-1 These organic materials, however, also have very high dry state stability up to ~ 300 degrees Celsius with loss of SO2/SO3 not occurring to > 350 degrees Celsius. Interestingly therefore these species offer exploitation potential at temperatures above currently available polymer-based electrolytes and below inorganic-based (e.g. oxide) materials. Possible applications falling in this temperature window are sensors, detectors and switches which need to function in high temperature hostile environments.