Self-doped polymers functionalization

Self-doped PANI are very interesting due to their unique electrochemical behavior unlike PANI, the self-doped polymer remains in its doped state in near neutral or alkaline media [28]. Fully self-doped PANIs are not easy to synthesize due to the lower reactivity of acid-functionalized anilines. Kim et al. [29, 30] introduced an alternative approach in the template-assisted enzymatic polymerization of aniline. Previously, only polyanionic templates had been used for PANI synthesis. However, acid-functionalized anilines bear a net anionic charge in aqueous solution, and attempts to use SPS as template with carboxyl-functionalized aniline resulted in red-brown colored polymers with no polaron transitions, regardless of the synthetic conditions. The use of polycationic templates, such as those shown in Figure 8.2 allowed the synthesis of linear and electrically conductive PANIs with self-doping ability due to the doping effect of the carboxyl groups present in the polymer backbone. 

Soluble conducting polymers can be solvent cast to form coatings. The addition of appropriate substituents to the polymer backbone or to the dopant ion can impart the necessary solubility to the polymer. For example, alkyl or alkoxy groups appended to the polymer backbone yield polypyrroles [117,118], polythiophenes [118], polyanilines [119,120], and poly(p-phenylenevinylenes) [97] that are soluble in common organic solvents. Alternatively, the attachment of ionizable functionalities (such as alkyl sulfonates or carboxylates) to the polymer backbone can impart water solubility to the polymer, and this approach has been used to form water-soluble polypyrroles [121], polythiophenes [122], and polyanilines [123]. These latter polymers are often referred to as self-doped polymers as the anionic dopant is covalently attached to the polymer backbone [9]. For use as a corrosion control coating, these water-soluble polymers must be cross-linked [124] or otherwise rendered insoluble. 

Self-doped derivatives of PANI containing an ionizable, negative charged functional group in their structure that acts as an inner dopant anion, hound to the pol nner backbone. There is no anion exchange between the polymer and the solution during the oxidation or reduction process. 

There are many other studies of ITO surface modification [277] for the purpose of enhanced hole injection. ITO work function can be changed by treatment with UV-ozone [269, 312, 330, 331], plasma [332-334], acids or bases [335-337], and charge transfer [338] as well as by binding dipolar molecules [339, 340] using organotin (or zirconium) alkox-ides [341-343]. The work function of ITO may be changed by electrostatically controlled self-assembled polymer layers [344-349]. The hole injection was also enhanced by electrochemically prepared thin films [350], p-type doped thin films [351 - 354] and plasma polymerized fluorocarbon films [355]. 

Self-doped conducting polymers are conjugated polymers, in which at least a fraction of monomer units contain covalently attached, ionizable functional groups that can act as immobile dopants. These polymers can be synthesized in a number of ways including chemical or electrochemical modification of the parent polymer as well as chemical or electrochemical polymerization of substituted monomers to form homo- or copolymers. ... 

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