Polyaniline/polyimide blends as gas sensors and electrical conductivity response to CO–N2 mixtures

The effects of dopant type, doping level, polyimide (PI) content and temperature on electrical conductivity response of polyaniline (PANI) and polyaniline/polyimide (PANI/PI) blends to CO–N₂ gas mixtures were systematically investigated. At the same doping level, HNO₃‐doped PANI has a greater electrical conductivity response and sensitivity towards CO than that of camphor sulfonic acid (CSA)‐doped PANI because the former has a more ordered structure. The interaction mechanism between CO and PANI is proposed to occur at the attack site, ? N?H? or the amine nitrogen where CO withdraws an electron. Addition of PI causes a small change in electrical conductivity under atmospheric conditions when PI content is below the percolation threshold value of 55 wt%. Addition of PI reduces brittleness and improves electrical conductivity sensitivity towards CO; the effect is more pronounced at higher temperatures. Copyright © 2005 Society of Chemical Industry