Highly Conducting Polyaniline Sensor towards detection of Benzene Vapours

Conducting polymer polyaniline (PANI) has been synthesized using in-situ oxidative polymerization process maintained at ice-cold (0 degrees C) conditions. The optical properties of the polymer have been investigated using UV-Vis spectroscopy. From the UV-Vis spectra of PANI matrix, the optical band gap of the polymer has been calculated. The electrical properties i.e. the gas sensing properties of PANI are studied under vacuum using two probe method at room temperature conditions. The transient current behavior atconstant voltage has been studied for the measurement of sensing properties of PANI towards varying concentration of aromatic organic compounds namely benzene in this case. The variations in response as a function of time have also been studied at different concentrations of benzene varying from 5 ppm to 20 ppm. Different parameters such as response (%), response time and recovery time have been calculated for having complete insight into the sensing characteristics of the polymer matrix. PANI exhibits efficient sensing towards even low level concentrations of benzene and response goes on increasing with increasing concentration. The enhanced conductivity of polymer matrix upon exposure of benzene vapors can be attributed to the attractive interaction between PANI and benzene which finally reduces the hopping distance for the carriers in polymer and results in increase in current.