Thermal stability study of conductive polyaniline/polyimide blend films on their conductivity and ESR measurement

Conductivity stability at thermal environment of conductive polyaniline-complexes/polyimide (PANI-complexes/PI) blends, which were doped by camphorsulfonic acid (CSA) and dodecylbenzenesulfonic acid (DBSA), respectively, were investigated by conductivity measurements, electron spin resonance (ESR) spectra, differential and scanning thermometer (DSC). In the conversion process of PANI/Polyamic acid (PAA) to PANI/PI, the blend endeavored some kinds of alteration such as decomplexation of moisture and solvent, dissociation of dopant, crosslinking of PANI chain, and the imidization of PAA chain. PANI-DBSA/PI showed higher thermal stability of conductivity than PANI-CSA/PI, and both samples showed nearly linear decay of conductivity with increasing temperature showing greatly enhancement of conductivity stability. When they were exposed at near or over glass transition temperature, the conductivity decay became faster. The conductivity stability at base environment was also higher for PANI-DBSA/PI due to difficulty in accessing of hydroxyl ion to PANI, which were resulted from dopant. DBSA-doped blends showed increased polaron mobility and concentration at relatively high temperature, which led to extremely higher conductivity and its stability at high temperature. Copyright © 2002 John Wiley & Sons, Ltd.