Counterion-induced processability

Reghu, M., Y. Cao, D. Moses, and A.J. Heeger. 1993. Counterion-induced processibility of polyaniline—transport at metal-insulator boundary. Phys Rev B 47 1758. 

Y. Cao, P. Smith, A. J. Heeger, Counterion induced processibility of conducting polyaniline and of conducting polyblends of polyaniline in bulk polymers, Synthetic Metals 1992, 48, 91. 

Another successful example is a commercialized product of dodecylbenzene sulfonic acid-doped polyaniline (PANI-DBSA) in xylene solution/dispersion in combination with matrix such as polyurethane, polyester, and so on. Thanks to the counterion-induced processability of polyaniline, pale green color antistatic coating with surface resistivity of 10 -10 Q/D can be produced (Figure 10.9), which has shown great success in antistatic application in electronic industry, mainly due to its good transparency, low cost, and long-term stability. 

With increasing environmental concerns, the development of water-based ICPs and their complex becomes a necessity. Extensive research has been conducted in this field, especially for polyaniline. Generally, water-based polyaniline can be obtained by three methods introduction of water-soluble substituent to backbone to gain water-soluble polyaniline [158, 159], emulsion polymerization to obtain water-dispersed polyaniline [160-163], and the cormterion-induced processability of doped polyaniline using a hydrophilic protonic acid [164, 165). The first two methods have a common problem of purification and efficiency. In contrast, the pure polyaniline is used in counterion-induced processability of doped polyaniline. The purification and efficiency problems do not exist with this method, so it is the most promising way to obtain water-based polyaniline. 

On the contrary, the optical spectra of PANI-CSA demonstrate the delocalized electronic structure of the wave functions near Ef in the conduction band [1160]. The improved sample quality originates from the counterion-induced processibility of PANI-CSA, where the functional group contained in the counterion induces... 

In 1991, the development of the counterion-induced processibility of polyaniline (PANI) enhanced the conductivity of PAN to 300-400 S/cm [27-30], These samples showed substantially weaker temperature dependence of (t T) than previous generation PANI [34,35], Moreover, for the first time, a doped conducting polymer showed a significant positive TCR in the temperature range 160-300 K [34,35],... 

Polyaniline can be rendered processible by the use of specific counterions (dopants). In this technique, the emeraldine base is mixed with appropriate dopant and the resulting mixture is dissolved in the appropriate solvent [37]. The solubility of emeraldine base in aqueous acetic acid as discussed above can be viewed as counterion-induced processibility. However, it was not until the recent discovery [7,8,37] that polyanilines doped with d,l-camphorsulfonic acid and dodecylbenzenesulfonic acid are soluble in common organic solvents such as m-cresol and toluene that counterion-induced processibility sparked interest in the scientific community. The d,l-camphorsulfonic acid/zn-cresol system, in particular, has generated considerable interest due to coupled effects of high transparency and conductivity (100-400 S/ cm). 

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