Polyaniline (PANI) has an exclusive representation probably owing to the fact that it has new applications in several fields of nano-technology. It is known for its straightforward synthesis process, high environmental stability and it can be easily doped by different acids. This chapter deals with the synthesis of PANI by several methods in which oxidative polymerization is the simplest and the most highly studied process. The synthesized PANI thin films can be deposited on different substances by a number of chemical and physical-based methods. These PANI thin films have been characterized by different techniques. FTIR and Raman spectroscopy used for structural analysis of synthesized PANI thin films while the crystalline nature determined by X-ray diffraction (XRD). Similarly, SEM, TEM, and AFM have been used for surface analysis of PANI thin films. The thermal and optical characteristics of PANI thin films studied by TGA and optical absorbance spectroscopy, respectively. The cyclic voltammetry (CV) curve gives information about the electrochemical reaction rate and the redox potential of PANI thin films.
TopIntroduction
The electrically conducting polymers (ECPs) have been the materials of the incredible enthusiasm for their applications in the current advancements. Among all CPs, polyaniline (PANI) has a wonderful portrayal most likely because of the way that polyaniline has new applications in a few fields of innovation. PANI is known for its simplicity of union, ecological solidness and simple to dope by protonic acids (Bhadra et al., 2009). PANI can be characterized by 1,4-coupling of aniline monomer units. PANI may present in different oxidation states, which are characterized by the proportion of amine to imine nitrogen particles in its spine. Leucoemeraldine (PANI-LE) base form of PANI is totally reduced form, whereas pernigraniline (PANI-PE) base is completely oxidized form. Similarly emeraldine base (PANI-EB) is half oxidized and half reduced form of PANI. Figure 1 (Jamadade et al., 2010, Yoon et al., 2011) PANI with these structures is cover in-spite of their physical and synthetic properties.
Figure 1. Different oxidation states of PANI and their conversion in each other (a) Leucoemeraldine Base (b) Emeraldine salt (c) Emeraldine base
Nonetheless, a protector blue emeraldine base might direct on the off chance that it is doped with protonic acids and end up green protonated ES. PANI-EB varies considerably from PANI-LE and PANI-PE, its conductivity has been obtained from -10-10 S/cm up to 100 S/cm after doping with different acids. PANI has potential applications in multidisciplinary fields due to extraordinary properties. It has a number of utilizations, for example, sensor (Sutar et al., 2007, Arsat et al., 2009, Matsuguchi and Asahi, 2011,Stamenov et al., 2012), electromagnetic shielding (Bhadra et al., 2008), biosensor (Dhand et al., 2011), memory devices (Tseng et al., 2005), and natural or polymer light-transmitting diodes (Long et al., 2011). Other than all the potential applications detailed above, PANI can likewise be utilized for erosion insurance for mild steel. Polyaniline microtubes/nanofibers and PANI-multiwalled carbon nanotubes nanocomposites might be utilized as microwave safeguards and electromagnetic shielding materials (Saini et al., 2009). Besides this chapter includes synthesis of PANI thin films by different methods, their deposition on substances, and characterization of PANI thin films.
Top1 Synthesis Of Pani Thin Films By Various Methods
Most regular union of polyaniline (PANI) has been accounted for as synthetic oxidative polymerization (Figure 2) of aniline can take place in the presence of acidic medium by using acid as dopant and polymerization is initiated by dropwise addition of ammonium persulphate (APS) which is used as an oxidizing agent at different temperature under constant stirring at east for 2 hours. After fulfillment of the polymerization mechanism (2 hours), the blue color solution has been observed, which is separated by filtration. The pure PANI can be obtained by washing above solution 3-4 times with double distilled water after that alcohol and (CH3)2CO until the filtrate becomes colorless which ensures that unreacted substances are entirely removed.
Figure 2. Oxidative polymerization of aniline to polyaniline