Polyaniline emeraldine salt, solubility

These observations provide a potential route to tailoring the properties (electronic, electrical, and optical) of conductive polymers, in this case HCSA fully doped polyaniline emeraldine salt. The reduced solubility of the film after exposure to m-cresol vapor also opens the door to a new method for the preparation of... 

More recently, Buchwald has reported the polymerization of the monomer in Eq. (38) [220]. This monomer was polymerized at 80 °C for 24 h in the presence of a catalyst comprised of Pd2(dba)3 and ligand 14. The polymers generated from this monomer bearing a Boc group are soluble in THF and chloroform with the aid of sonication. After isolation, the Boc group could be removed by thermolysis at 185 °C or by protonolysis in air. Emeraldine or the emeraldine salt forms of polyaniline result. 

For organic solvent solubility, an alternative approach to solubilising polyanilines and polypyrroles, without sacrificing high electrical conductivity, is the use of surfactant-like dopant anions. With polypyrrole this has recently been achieved via oxidation of the pyrrole monomer with ammonium persulfate in the presence of dodecylbenzene sulfonate [128,129]. Similarly, the conducting emeraldine salt form of PAn.HA can be readily solubilised in a range of organic solvents via the use of camphorsulfonic acid or dodecylbenzenesulfonic acid as the dopant, HA [130,131]. 

Unlike ring sulfonated polyaniline, the fully sulfonated, water-soluble, polyaniline, poly(2-methoxyaniline-5-sulfonic acid), is shown to be remarkably inert to alkaline dedoping and remains in the conducting emeraldine salt form even in 2.0 M NaOFi [164], The UV-Vis near-infrared spectra of poly(2-methoxyaniline-5-sulfonic acid) solution as a function of plT are shown in Figure 2.28. In water, the absence of a localized polaron band in the range of 750-900 run and presence of a broad absorption in NIR suggests an extended coil conformation... 

Shamon and Fernandes [146] have reported that use of sulphate free poly (styrene sulphonic acid) PSSA as an electrolyte to yield a water soluble poly aniline containing at least 25 C6H4NH units. The evaporation of this aqueous solution yields emerald solid with green metallic lustre. However, on addition of acids like HCl, H2SO4 or their salts in this aqueous solution causes the precipitation of emeraldine salt, suggesting that PSSA is loosely bound to polyaniline. 

Previously, the enhancement of the device performance in ITO/polyaniline/MEH-PPV/Ca devices has also been observed (9). The metallic emeraldine salt form of PANI is prepared by doping and complexation with functionalized sulfonic acids (e.g. camphor sulphonic acid, CSA), yielding a conducting PANI-complex soluble in common organic solvents. Hence, based on the results obtained from our research, we conclude that the enhancement of the device performance in ITO/PANI/MEH-PPV/Ca devices is probably due to the fact that the CSA dopes the surface of MEH-PPV and subsequently eidiances the charge injection and lowers the device operating voltage. 

A water-soluble externally (HCl)-doped conducting polyaniline was obtained by sulfonation of the emeraldine salts using chlorosulfonic acid in dichloroethane at 80 °C. ... 

A wide range of alkyl- and alkoxy-substituted polyanilines of the general types 6 and 7 have been synthesized by the chemical or electrochemical oxidation of appropriately substituted aniline monomers.41,i32-i3s Such substitution imparts solubility in organic solvents upon the emeraldine salt products that is markedly improved over the parent (unsubstituted) PAn.HA salts. The poly(2-methoxyaniline) (POMA) species, in particular, has been the subject of extensive studies. This species has the additional attractive feature of being soluble in water after being wet with acetone. 

Emeraldine salt films can be prepared directly from solutions when particular counterions are used to impart solubility. The most extensively studied system is the camphorsulfonic acid-doped ES as cast from a m-cresol solution. Lunzy and co-workers have considered the crystal structure of camphorsulfonic acid-doped polyaniline (PAn-CSA) as cast from m-cresol. Although presenting a clear crystal structure with a degree of crystallinity of 25%, the unit cell structure has no resemblance to the structures formed by the emeraldine base. 

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