Polypyrrole (Ppy) was synthesized using Ammonium Peroxy Disulfate (APS) as oxidant in a standard ratio of monomer to oxidants at 5℃. Attempts were made to increase the electrical conductivity by using various dopants viz. Lithium per Chlorate (LiClO<sub>4</sub>), para-Toluene Sulfonate (p-TS) and Napthalene Sulfonic acid (NSA). The materials were characterized using FTIR, X Ray diffraction and SEM. The electrical conductivity was measured by two probe method and was found to be in the range of 10<sup>-3</sup> S/cm. Thin films of these preparations were casted on the interdigited electrodes to study the detection of gas such as ammonia. It was found that for the pure Ppy when ammonia gas was allowed to flow in, there was a sudden increase in the current, which decreased rapidly when gas was stopped. However when Ppy doped with p-TS, NSA and LiClO<sub>4</sub>, the trend was reversed.
S.C. Hernandez, D. Chaudhari, W. Chen, N. Myung and A. Mulchandani, “Single Polypyrrole Nanowire Ammonia Gas Sensor,” Inter Science, Vol. 19, No. 19-20, 2007, pp. 2125-2130.
S. Cosnier, C. Gondran, R. Wessel, F.-T. Montforts and M. Wedel. “A Poly(Pyrrole-Cobalt (II) Deuteroporphyrin) Electrode for the Potentiometric Determination of Nitrite,” Sensors, Vol. 3, No. 7, 2003, pp. 213-222. doi:10.3390/s30700213
M. F. Mabrook, C. Pearson and M. C. Petty, “Inkjet- Printed Polypyrrole Thin Films for Vapor Sensing,” Sensors and Actuators B, Vol. 115, No. 1, 2006, pp. 547-557. doi:10.1016/j.snb.2005.10.019
H. Bai and G. Shi, “Gas Sensors on Conducting Polymers,” Sensors, Vol. 7, No. 3, 2007, pp. 267-307. doi:10.3390/s7030267
R. A. Bissell, K. C. Persaud and P. Travers, “The Influence of Non Specific Molecular Partitioning of Analytes on the Electrical Response of Conducting Organic Polymer Gas Sensors,” Physical Chemistry Chemical Physics, Vol. 4, No. 14, 2002, pp. 3482-3490. doi:10.1039/b201292h
S. C. Hernandez, D. Chaudhuri, W. Chen, N. V. Myung and A. Mulchandani, “Single Polypyrrole Nanowire Ammonia Gas Sensor,” Electroanalysis, Vol. 19, No. 19-20, 2007, pp. 2125-2130.
C. Nylabder, M. Armgrath and I. Lundstrom, “An Ammonia Detector Based on a Conducting Polymer,” Proceedings of the International Meeting on Chemical Sensors, Fukuoka, 19-22 September 1983, pp. 203-207.
H. Bai and G. Q. Shi, “Gas Sensors Based on Conducting Polymers,” Sensors, Vol. 7, No. 3, 2007, pp. 267-307.
Q. Fang, D. G. Chetwynd and J. W. Gardner, “Conducting Polymer Films by UV―Photo Processing,” Sensors and Actuators A, Vol. 99, No. 1-2, 2002, pp. 74-77. doi:10.1016/S0924-4247(01)00894-9
L. Ai Mashat, H. D. Tran, W. Wlodarski, R. B. Kaner and K. K. Zadeh, “ Conductometric Hydrogen Gas Sensors Based on Polypyrrole Nanofibers,” Sensors Journal, Vol. 4, No. 4, 2008, pp. 365-370.
A. Joshi, S. A. Gangal, N. Padma, D. K. Aswal and S. K. Gupta, “Gas Sensing Properties of Polypyrrole Thin Films,” BARC Newsletter, No. 297, 2008, pp. 236-239.
S. Hosein and A. A. Entezami, “Polypyrrole Based Toxic Gas Sensors by Mass and Conductivity Measurements,” Iranian Polymer Journal, Vol. 8, No. 3, 1999, pp. 205- 213.
S. S. Jeon, H. H. An, C. S. Yoon and S. S. Im, “Synthesis of Ultra-Thin Polypyrrole Nanosheets for Chemical Sensor Applications,” Polymer, Vol. 52, No. 3, 2011, Pages 652-657. doi:10.1016/j.polymer.2010.12.021
G. Harsanyi, “Highly Sensitive and Selective Ammonia Sensor for Environmental Monitoring and Workplace Safety Applications”.
H. Yoon, M. Chang and J. Jang, “Sensing Behavior of Polypyrrole Nano Tubes Prepared in Reverse Micromulsions: Effects of Tranducers Size and Transduction Mechanism,” Journal of Physical Chemistry B, Vol. 110, No. 29, 2006, pp. 14074-14077. doi:10.1021/jp061423b
V. Saxena, S. Choudhary, S. C. Gadkari, S. K. Gupta and J. V. Yakhmi, “Room Temperature Operated Ammonia Gas Sensor Using Polycarbazole Langumuir-Blodgett Film,” Sensors and Actuators B, Vol. 107, No. 1, 2005, pp. 277-282. doi:10.1016/j.snb.2004.10.011
L. Jiang, H. K. Jun, Y. S. Hoh, J. O. Lim, D. D. Lee and J. S. Huh, “ Sensing Characteristics of Polypyrrole-Poly (Vinyl Alcohol) Methanol Sensors Prepared by in Situ Vapour State Polymerization,” Sensors and Actuators B Vol. 105, No. 2, 2005, pp. 132-137. doi:10.1016/j.snb.2003.12.077
R. Ansari, “Polypyrrole Conducting Electroactive Polymers: Synthesis and Stability Studies,” E-Journal Chemistry, Vol. 3, No. 13, 2006, pp. 186-201.
H. Kato, O. Nishikwa, T. Matsui, S. Honma and H. Kokado, “Fourier Transform Infrared Spectroscopy Study of Conducting Polymer Polypyrrole Higher Order Structure of Electrochemically Synthesized Film,” The Journal of Physical Chemistry, Vol. 95, No. 15, 1991, pp. 6014- 6016. doi:10.1021/j100168a055
N. V. Bhat, A. P. Gadre and V. A. Bambole, “Structural, Mechanical and Electrical Properties of Elctro-Poly- merized Polypyrrole Composite Films,” Journal of Applied Polymer Science, Vol. 80, No. 13, 2001, pp. 2511- 2517. doi:10.1002/app.1359
T. K. Vishnuvardhan, V. R. Kulkarni, C. Basavaraja and S. C. Raghavendra, “Synthesis, Characterization and A.C. Conductivity of Polypyrrole/Y2O3 Composites,” Material Science, Vol. 29, No. 1, 2006, pp. 77-83.
H. Eisazadeh, “Studying the Characteristics of Polypyrrole and Its Composites,” World Journal of Chemistry Vol. 2, No. 2, 2007, pp. 67-74.
R. Turcu, M. Brie, G. Leising, V. Tosa, A. Mihut, A. Niko and A. Bot, “ FTIR Reflectance Studies of Electrochemically Prepared Polypyrrole Films,” Applied Physics A, Vol. 67, No. 3, 1998, pp. 283-287. doi:10.1007/s003390050772
S. A. Waghule, S. M. Yenorkar, S. S. Yawale and S. P. Yawale, “SnO2/Ppy Screen-Printed Multilayer CO2 Gas Sensor,” Sensors and Transducers Journal, Vol. 79, No. 5, 2007, pp. 1180-1185.
R. Naillathambi, “Preparation and Characterization of Conducting Polymers and Its Composites for Gas Sensors,” PhD Dissertation, University of Bombay, Mumbai, 1996.