Poly emeraldine base form

The structure of the semiconducting emeraldine base form of poly aniline is [(lA)(2A)]n... 

A more efficient system would employ a chromophore with a long-lived excited state that was capable of excited state electron transfer to form the oxidized polymer directly. A key example involved excitation into the MLCT band of [Ru(dmb)3p (dmb = 4,4 -dimethyl-2,2 -bipyridine) which results in an excited state reduction potential of +0.77 V vs. SCE in chloroform [126]. The oxidation potential required to switch the emeraldine base form (EB) of eith polyaniline [PANi(EB)] or poly(2,5-dimethoxyaniline) [PDMA ebJ to the conductive form is approximately +0.40 V vs. SCE [130]. Thus, the photoinduced oxidation of either polymer by [Ru(dmb)3p is thermodynamically feasible according to the excited state reaction illustrated in Eq. (2). 

Polyaniline, one of the most studied conducting polymers (in general as well as for corrosion protection), is usually obtained by protonation of what is called the emeraldine base form, shown in Figure 2. The protonation reaction does not change the number of electrons in the polymer backbone. However, starting at the leucoemeraldine form of polyaniline, one would obtain the emeral e salt (conducting) form of polyaniline by an oxidation reaction. Protonic doping has also been observed in the case of alkoxy substituted poly(para-phenylene vinylene) (PPV) ... 

The technique uses as-synthesized polyaniline (doped form). All other techniques that are currently available for preparing coatings and films use the emeraldine base form, which must be synthesized from the doped poly-... 

Wrobleski et al. and Thompson et al. [617, 942] studied a variety of CPs, including P(ANi) and poly(thiophene) derivatives (see below), for corrosion protection of steels in marine environments. An immediate need they sought to fulfill was protection in the space launch environment, which included HCl fumes, elevated temperatures, and salty air. The Zn chromate coatings in use for the purpose were frequently leached out by the HCl vapors. These workers synthesized P(ANi) chemically using persulfate oxidation, converted it into the soluble (reduced), emeraldine base form, and formed a solution in NMP. The solution was then applied by dip- and spraycoating methods, with the coatings then re-doped chemically by immersion in... 

Fig. 1. (a) Leucoemeraldine base (b) emeraldine base (c) pernigraniline base (d) polyCparaphenylene sulfide) le) emeraldine hydrochloride salt polymer (f) poly(orthotoluidine) (emeraldine base form) (g) sulfonated polyaniline (self-doped salt form). 

Fig. 26 Reversible electrochemical switching between vesicles and its puck-like fragments TAPEG-EB tetraaniline-modified poly(ethylene glycol) with tetraaniline in the emeraldine base form, TAPEG-LEB with tetraanaline in the leucoemeraldine form (reprinted with permissitm fiorn [298]. Copyright 2011 American Chemical Society)...

The common form of polyaniline is a 1 1 combination of alternating reduced (A) and oxidized (C) units it is termed emeraldine (or emeraldine base). The emeraldine base is essentially non-conductive, but its conductivity increases by 9-10 orders of magnitude by treating with aqueous protonic acids. The conductive form of poly aniline can therefore be roughly depicted as a 1 1 combination of alternating A and D units. 

FIGURE 9.1. Repeat units of the pyridine-containing polymers and other polymers used in the study (a) poly(p-pyridine) (PPy) (b) poly(/ -pyridyl vinylene) (PPPyV) (c) copolymer of PPY and PPyV [PPyVP(R)2V] (d) wrapped copolymer of pyridylvinylene and penylenevinylene ( PPyVPV) (e) wrapped copolymer of dithienylene and phenylene ( PTP) (f) emeraldine base (EB) form of polyaniline (g) sulfonated polyaniline (SPAN). 

Figure 1,45. Various forms of PANl (a) leucoemeraldine base (LEB, poly(paro-phenylene amine)) (b) pemigraniline base (PNB, poly(poro-phenylene imine)) (c) emeraldine base (EB) (d) emeraldine salt (ES), bipolaron form (e) emeraldine sail, polaron form.

Various forms of doped PANI are discussed by Moon el al. [300]. PANls doped with Cl and CIO4" are synthesized in powder form, and HSO4 -doped PANI is obtained by dissolving a Cl -doped form in concentrated H2SO4 and allowing H2O from the atmosphere to precipitate it from this solution. The Cr-doped form is found to be the most crystalline one and to have the most detailed diffraction pattern. The diffraction from the other preparations is similar a structural analysis has not been carried out by the authors. De-doping in aqueous NH OH in this case leads to PANI base with distinct crystallinity, in contrast to results from earlier studies. The similarity between the molecular stnicture of emeraldine base and that of poly(pap-a-phenylene sulphide) and poly(para-pheny-lene oxide) is inferred from common features of the diffraction patterns of the three polymers. 

Figure 6.47, The chemical stnictures for (a) poly-acetylenc and polyanilinc in (b) the insulating emeraldine base (EB) form (c) the conducting emeraldine salt (ES) form (d) polythiophene (e) poly(3-mcthylthiophene) and (f) polypyrrole.

We have re-analyzed the available data in comparison with the results of band structure calculation to provide the basis for an understanding of the electronic structure of the four principal forms of poly aniline the fuUy reduced leucoemeraldine, (1 A)n the partially oxidized emeraldine base, [(1 A)(2A)]n the oxidized and fully protonat emeraldine salt, [IS] (A )n and the fully oxidized bipolaron lattice, (-B-NH+=Q=NH+-)n. 

Emeraldine base (EB) and emeraldine salt (ES) forms of poly(o-methoxyaniline) (POMA), are able to construct biomolecular hybrids with DNA showing a fibrillar network structure of invariant fibrillar diameter for different hybrid compositions. An approximate model of the Na-DNA/POMA-ES system indicates nanostmctured self-organized assembly of the components in the hybrid [100]. However, the most desired property of fibers for the electronic devices technology is their orientation in a definite direction. Self-assembly of oriented PANI arrays can be achieved in the presence of inorganic acids and by changing the PANI/acid concentration ratio, (Fig. 1.6) [101, 102]. 

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