**6. References**

128 Electropolymerization

Fig. 9. Nyquist plots for poly(Py), poly(Py-SNS)(100:1 mole ratio) and poly(SNS) in 3.5% (W/V) NaCl solution: A) Exploded view in the high frequency range, B) Proposed

containing SNS leads it to extensive applications in many fields.

According to these results (Table 2), we can notice a decrease in the charge transfer resistance value in the case of the polypyrrole in the presence of SNS systems as compared to polypyrrole alone. The Rct (Rct: charge transfer resistance) values obtained for polypyrrole and poly(SNS) are 5.81 and 2282 *Ω.cm2* respectively. This value decreases in the presence of SNS to 1.46 *Ω.cm2*. The polypyrrole film formed in the presence of SNS is more conductive. On the other hand, in the presence of SNS, value of the capacitance of the double layer, CPE1, rises from 8.0E-4 to 0.67 μF.cm-2 which can be attributed to an increase in the electrode surface area. This change in the capacitance strongly supports the hypothesis of the incorporation of SNS in the polypyrrole film. Also, these results support the results of CV in the Figure 9. In the presence of SNS, the conductivity of polypyrrole is improved. Increased value of CPE1 for polypyrrole in the presence of SNS compared to pure polypyrrole confirmed the easy electron transfer of ferro/ferricyanide redox system for poly(Py-SNS) (Fig. 8). Improvement of the conductivity, electroactivity and redoxability of polypyrrole

The resulted poly(Py-SNS)(100:1 mole ratio) showed a considerable increase in the electroactivity, redoxability, and the rate of polymerization in comparison to polypyrrole alone. The cyclic voltammograms of electron transfer ferro/ferricyanide redox system on different modified GC electrode showed that the rate of charge transfer for polypyrrole in the presence of SNS increased in comparison to pure polypyrrole. In addition, the conductivity of polypyrrole was studied by electrochemical impedance spectroscopy. The obtained Rct value for polypyrrole is 5.81 *Ω.cm2*, whereas the value decreases to 1.46 *Ω.cm2* in

equivalent circuit

**4. Conclusions** 


**7** 

*India* 

**Polypyrrole Composites: Electrochemical** 

R. N. Singh, Madhu and R. Awasthi

*Banaras Hindu University* 

**Synthesis, Characterizations and Applications** 

The electronically conducting polymers (ECPs), such as polypyrrole (PPy), polythiophene (PT) and polyaniline (PANI) are known to possess unusually high electrical conductivity in the doped state. Due to this, these materials have been of great interests for chemists as well as physicists since their electrical properties were reported (Diaz et al., 1979). The ECP films behave like a redox polymer and have potential applications in electrocatalysis, solar energy conversion, corrosion, electronics, etc. The redox polymer reaction is accompanied by a change in the electrical properties of the film from an insulator to an electrical conductor involving both electron and ion transport within the film (Kaplin &

Conducting polymers can be synthesized either chemically or electrochemically. Electrochemical synthesis is the most common method as it is simpler, quick and perfectly controllable. PPy is one of the most interesting conducting polymers since it is easily deposited from aqueous and non-aqueous media, very adherent to many types of substrates, and is well-conducting and stable. Electrochemical polymerization produces thin films with a thickness of few micrometers on an electrode surface (Diaz et al., 1979), while a chemical oxidation yields a fine-grained material. However,the yield and quality of the resulting polymer films are influenced by several factors, such as nature and concentration of monomer and the counter ion, solvent, cell conditions (e.g. electrode and applied

ECPs can be modified in several ways (Juttner et al., 2004) to obtain tailored materials with special functions: (i) derivatization of the monomer by introducing aliphatic chains with functional groups; (ii) variation of the counterion, incorporated for charge compensation during the polymerization process; (iii) inclusion of neutral molecules with special chemical functions and (iv) formation of compounds with noble metal nanoparticles as catalyst for

The electropolymerization reaction is a complex process and its mechanism is still not fully understood. A number of mechanisms have been proposed (Genies et al., 1983; Kim et al., 1988; Asavapiriyanont et al., 1984; Qui & Reynolds, 1992) and are comprehensively reviewed (Sadki et al. 2000; Ansari, 2006 & Pina et al. 2011). Among these, Diaz's mechanism is the most accepted one (Genies et al., 1983) and supported by Waltman and Bargon (1984 & 1985) also. In this mechanism, the pyrrole (Py) activation occurs through electron transfer

potential), temperature and pH (Sadki et al. 2000; Ansari, 2006 & Pina et al. 2011).

electrochemical oxidation and reduction processes.

**1. Introduction** 

Qutubuddin, 1995).

electropolymerization of thiophene in the presence of catalytic amount of 1- (2‐pyrrolyl)-2-(2-thienyl) ethylene (PTE). *Journal of Applied Polymer Science,* Vol. 108, No. 4, pp. 2700-2706.

