Optical Properties of Polyanilines

Semiempirical molecular orbital calculations,58 and more recently, ab initio calculations59 on the conducting emeraldine salt form of PAn predict, in contrast to PPy and polythiophene, the presence of a single broad polaron band deep in the band gap. This band is half-filled, giving rise to an ESR signal.60 

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Prior studies demonstrated that the properties of chemically synthesized polyaniline could be modified by the type of synthesis -electrochemical, chemical, or potential cycling methods (1-5). In addition the optical properties of polyaniline could be controlled by the substituents on the nitrogen or aromatic ring (6,7). Enzyme-catal5rzed polymer syntheses in organic solvents with different amounts of water were described in earlier publications (7-10), and nonlinear optical properties of some of these pol5miers were reported (11). This paper describes the horseradish peroxidase-catalyzed synthesis of polyaniline and the evaluation of its optical properties to determine differences, if any, between this polyaniline and those chemically synthesized. 

Barbero, C., and R. Kotz. 1994. Nanoscale dimensional changes and optical-properties of polyaniline measured by in-situ spectroscopic ellipsometry. J Electrochem Soc 141 859. 

Switching properties Chemical properties Mechanical properties of polyaniline Electrochemically Prepared Films Solution Cast Films and Fibers Optical properties of polyanilines Circular dichroism spectra... 

Polyaniline-nitrilic rubber composites have been prepared using rubber-coated anodes for electropolymerization. The resultant material has the mechanical properties of a crosslinked elastomer with the electrical and electro-optical properties of polyaniline. The polymer composite properties vary markedly with the electrolyte used during electropolymerization. 

As with polypyrrole (PPy), the electrical, chemical, and mechanical properties of polyaniline (PAn) are inextricably linked. In addition, PAn has spectacular optical and chromic properties that distinguish it from other conducting electroactive polymers (CEPs). The current state of knowledge concerning properties of PAn is reviewed in this chapter. 

F. Yakuphanoglu, R. Mehrotra, A. Gupta, and M. Munoz, Nanofiber organic semiconductors The effects of nanosize on the electrical charge transport and optical properties of bulk polyanilines, J. Appl. Polym. Sci, 114, 794-799 (2009). 

Whatever is the y value, the polyaniline is always an insulator its conducting properties only appear when the half-reduced-half-oxidized form (emeraldine) is treated with an acidic solution. The polymer chain is then protonated. The optical and magnetic properties of polyaniline also both depend on the oxidation and protonation states. ... 

ELECTRICAL, OPTICAL AND MAGNETIC PROPERTIES OF POLYANILINE PROCESSED FROM SULFURIC ACE) AND IN SOLUTION IN SULFURIC ACE)... 

Composites of conducting polymers, e.g., polyaniline and PEDOT, with polyacids, e.g., poly (2-acrylamido-2-methyl-l-methyl-l-propanosulfonic add) (PAMPS), have been shown to be electro-chromic. The polyadd acts as a dopant for the polymer film with the optical properties of the composite being contributed by the conducting polymer. The composites are formed by dther chemical or electrochemical polymerization of the electrochromic component monomer in the presence of the polyacid. Films of polyaniline-PAMPS switch from yellow to green and finally to blue on oxidation [228,229]. Composite films of PEDOT and PAMPS show similar electrochromic properties to PEDOT with the films switching from dark blue in the neutral state to Kght sky blue in the oxidized state [140,230,231]. 

T. Kawai, H. Mizobuchi, N. Yamasaki, H. Araki, K. Yoshino, Optical and magnetic-properties of polyaniline derivatives having ionic groups, Japanese Journal of Applied Physics Part 1 - Letters 1994, 33, L357. 

Figure 9.9 In Situ Vis-NIR absorption spectra recorded upon doping of poly(3-decylthiophene). Reprinted with permission from /. Pron, P. Rannou, M. Zagorska, Spectroscopy and spectroelectrochemistry of polyanilines and polythiophenes, in Electronic and Optical Properties of Conjugated Systems in Condensed Phases, Research Signpost, Trivandrum, 2003. Copyright (2003) Research Signpost...

The electrical and optical properties of polyacetylene (CH) , polyaniline (PANI), polypyrrole (PPy), polythiophene (PT), po-ly(p-phenylene vinylene) (PPV), poly(p-phenylene) (PPP), and poly(thienylene vinylene) (PTV) are some of the extensively studied conducting polymers [3,1049]. 

Calculations conducted at the correlated level provide valuable information on the evolution upon deriva-tization of the lowest optical transition and hence of the wavelength of the emitted light. As is the case in the PPV oligomers, the lowest absorption in all the derivatives can be mainly described by an electron transition between the HOMO and LUMO levels there is, however, one exception in the case of compound VII, poly (1,4- phenylenemethylidynenitrilo-1,4- phenylene -nitrilomethylidyne) (PPI), (see Fig. 1,1) for which a mixing of several configurations is needed to properly describe the absorption peak. Note that such behavior is reminiscent of the typical optical properties of the emer-aldine base form of the polyaniline family [64], whose molecular structure presents similarities to that of derivative VII. 

Sezer, A., Gurudas, U., Collins, B Mckinlay, A and Bubb, D.M. (2009) Nonlinear optical properties of conducting polyaniline and polyaniline-Ag composite thin films. Chemical Physics Letters, 477,164-168. 

Khan JA, Qasim M, Singh BR et al (2013) Synthesis and characterization of structural, optical, thermal and dielectric properties of polyaniline/CoFe204 nanocomposites with special reference to photocatal5rtic activity. Spectrochim Acta Part A Mol Biomol Spectrosc 109 313-321... 

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