Synthesis of Polypyrrole Using Ferric Chloride (FeCl<sub>3</sub>) as Oxidant Together with Some Dopants for Use in Gas Sensors

Abstract

Polypyrrole (Ppy) was synthesized using Ferric Chloride (FeCl 3) as oxidant. The ratio of monomer to oxidant was 1:2.4. The polymerization was carried out at 5˚C. Attempts were made to increase the electrical conductivity by using various dopants viz. Lithium per Chlorate (LiClO 4), 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 −3 to 10 −2 S/cm. Thin films of these preparations were casted on the interdigited electrodes to study the detection of gases such as ammonia and LPG. It was found that for the pure Ppy and one doped with LiClO 4 , when ammonia gas was allowed to flow in, there was a sudden increase in the current, which decreased rapidly when gas was stopped. This behavior is in contradiction to that observed in earlier investigations where Ppy was prepared by electrochemical method. However when Ppy doped with p-TS and NSA were used, the trend was reversed. Similarly it was noted that for pure Ppy and one doped with LiClO 4 , p-TS and NSA there was an increase in the current when LPG gas was brought in. However the response to LPG was somewhat low as compared ammonia gas.

Synthesis and Characterization of Conductive Polypyrrole: The Influence of the Oxidants and Monomer on the Electrical, Thermal, and Morphological Properties

“…Therefore, in a chemical oxidative polymerization of pyrrole monomer, many researchers have reported using different oxidants for synthesizing PPy. For instance, FeCl 3 has been used as an oxidant for synthesizing PPy films in order to study the detection of gases such as ammonia [15,16], and the use of ammonium persulphate as an oxidant focuses mainly on conductivity behavior. While Khamlich et al [17] have used ferric chloride as an oxidant for preparing polypyrrole/graphene nanocomposites, investigating the influence of nanofiller on the final properties.…”

Enhanced electrocapacitive performance and high power density of polypyrrole/graphene oxide nanocomposites prepared at reduced temperature

“…Such an increase in the peak current was more pronounced for PNCs prepared at 10 ± 1°C over those prepared at 30 ± 1°C [13][14][15][16][17][18][19] (Fig. 7a).…”

“…The treated substrate was dried at room temperature for 2 h and then at 100°C/400 mmHg for 48 h. This afforded cathodes with a mass thickness of electroactive materials by 5 ± 1 mg over the 316-SS substrate [25]. low temperature liberates PPY nanoparticles [12] with improved specific and electrochemical conductivities [13][14][15][16][17][18][19].…”

Electroconducting materials based on polypyrrole

“…sensors, batteries, electrochemical capacitors, with controlled release of the anions out of polymer film being of particular significance during medical applications [10,28,[68][69][70][71][72][73][74].…”

“…Polymerization by ectropolymerization, metal-catalyzed coupling reactions, and chemical oxidative polymerization was successfully used for synthesis of polymers constructed of heterocyclic (pyrrole, thiophene, furan, etc) [26][27][28][29][30] and aromatic units (phenylene derivatives, aniline) [31][32][33][34][35][36][37], but also photochemical polymerization and polymerization cathalyzed by enzimes has been also applied [38,39] Method of chemical polymerization can be applied for synthesis of all types of conducting polymers, including those which cannot be obtained electrochemically [40]. On the other hand, the electroconductivity of polymers obtained chemically is lower compared to the electrochemically synthesized equivalent [41].…”