Sulfonic acid polypyrrole

Figure 8 Thickness dependence of total shielding efficiency (SET) of highly conducting polymers (A) stretched heavily iodine doped Tsukamoto polyacetylene, (B) camphor sulfonic acid doped polyaniline cast from m-cresol solvent, (C) PFg doped polypyrrole.

Polyanilines NSA naphthalenesulfonic acid PANI - Polyaniline PDMA-PSS — Poly (-dimethoxyaniline-poly (4-styrene sulfonic acid) PANSA — 8-anilino-l-napthalene sulfonic acid PPY polypyrrol PESA polyester sulfonic acid PVS - polyvinyl sulfonate SEM — Scanning electron Microscopy PVA poly(vinyl alcohol)... 

Cao and coworkers reported that problems in processing of doped PANi could be solved by the use of functionalized protonic acids. Indeed, solutions of camphor-sulfonic acid doped with PANi in m-cresol show liquid crystallinity and high electrical conductivity, according to Smith and his coworkers. This prompted additional work with this and other polymers. Unfortunately, the conductivity of cast films of solutions of polypyrrole (PPy) doped with dodecyl benzene sulfonic acid in m-cresol is low (ca. 10 S/cm). 

Fig. 3.10. Some of the more commonly encountered organic conductor materials (a) polypyrrole, (b) polyaniline, and (c) poly(3,4-ethylenedioxythiophene) (PEDOT). When combined with water soluble organic acids (e.g. sulfonic acids like benzosul-fonic acid) many of these polymers can form doped complexes which are highly conductive and can be dispersed into suspension. Substituted versions of these polymers which are self-doped have also been developed.

Matsue et al. [27] were the first to explore an enzyme-based OECT biosensor. They used Diaphorase as the entrapped enzyme in a polypyrrole transducing layer for the detection of NADH via a redox mediator (the sodium salt of anthraquinone-2-sulfonic acid). The net result was the conversion of polypyrrole from its conducting state to its insulating state in the presence of NADH. The device showed a response time of 15--20 min in the presence of NADH. Later Nishizawa et al. [26] exploited the pH sensitivity of the polypyrrole film for the design and fabrication of OECT sensors for pH and for pencillin. The Penicillinase enzyme was entrapped in a membrane which was coated with a polypyrrole film, in which a decrease in pH was observed in the presence of penicillin due to the hydrolysis of penicillin by Penicillinase. 

The introduction of sulfonic acid groups in the alkyl side chains affords water-soluble self-doped polypyrrole. Using the sodium salt of the 3-alkylsulfonic acid pyrrole, the monomer acts as electrolyte for the electrochemical synthesis as well. A second long alkyl chain on the opposite side of the pyrrole ring affords a highly ordered lamellar polymer also soluble in chloroform [96]. 

Polyaniline and its substituted derivatives, such as poly(o-toluidine), poly(o-anisidine), poly(N-methylaniline), poly(N-ethylaniline), poly(2,3-dimethylaniline), poly(2,5-dimethylaniline) and poly (diphenylamine) have been reported [36] to show measurable responses (sensitivity 60%) for short chain alcohols (viz., methanol, ethanol and propanol) at concentrations up to 3000 ppm. The change (decrease) in resistance of the polymers on exposure to alcohol vapors has been explained based on the vapor-induced change in the crystallinity of the polymer. Polypyrrole (PPy) incorporated with dodecyl benzene sulfonic acid and ammonium persulfate has been reported to show a linear change in resistance when exposed to methanol vapor in the range 87-5000 ppm [37]. The response is rapid and reversible at room temperature. 

Films prepared in a similar manner with Hydrin C are those utilizing poly(N,N -dimethyl-2,2 -bipyrrole) [220], and polypyrrole [221]. Electrochromic films of Hydrin C and poly(o-methoxyaniline) have also been produced in which the aniline polymer is chemically polymerized in the presence of p-toluene sulfonic acid and blended with Hydrin C with the blend cast from solution [219]. Another example in which an electrochromic polymer was electrochemically polymerized in the presence of an insulating polymer is that of polypyrrole-polyjether urethane) or polypyrrole-poly(ethylene-co-vinyl alcohol) composite films [222]. Both films switched between a yellow reduced state to a bluish brown oxidized state, similar to polypyrrole. 

Example 7 Polypyrrole-Sulfonic Acid - Copolymerization of Poly pyrrole-co- 3-(pyrrol-l-yl)propanesulfonate] (7a)... 

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