Dodecylbenzenesulfonic acid doped

The general model of the crystal structure proposed by Dufour et al. is drawn schematically in Figure 4.6. In this structure, the alkyl chains separate the ordered polyaniline chains and the separation of the latter depends upon the alkyl chain length. In fact, detailed analysis suggests that the alkyl chains are interdigitated, as shown in the figure. Similar structures have been proposed for dodecylbenzenesulfonic acid doped PAn 191. 

The addition of templates enabled the enzymatic production of conducting polymers with well-defined structure.67 In using sulfonated polystyrene (SPS) as a template, the resulting polymer was soluble in water and the conductivity reached 5 x 10 3 S/cm without doping. Besides SPS, a strong acid surfactant (sodium dodecylbenzenesulfonic acid) or poly(vi-nylphosphonic acid) provided a suitable local template environment leading to the formation of conducting poly aniline. 

Polyaniline (PAn) is most amenable to solution processing. The emeraldine base (EB) form of PAn is soluble in selected solvents such as methyl pyrrolidinone1 or strong acids.2 3 More recently, it has been discovered that solubility of the doped form can be induced by the use of appropriate surfactant-like molecules as dopants.4 Camphorsulfonic acid (HCSA) and dodecylbenzenesulfonic acid have proved particularly useful in this regard. Once solubilized, these PAn s can be cast into sheets or blended with other conventional polymer structures. For example, the pres-... 

Others8 have blended PAn doped with dodecylbenzenesulfonic acid with poly(vinyl alcohol) (PVA) in water or with polyacrylate in organic solvents to obtain transparent conductive composites. 

Organic Acids, Sulfonic Acids and Propionic Acid. The electrical conductivity of PDDT is about four to five orders of magnitude lower than in the case of iodine, but the electrical conductivity of the films is environmentally more stable. In addition, the dopant 4-dodecylbenzenesulfonic acid can act as a plasticizer for the PT film [273]. 1-Naphthalenesulfonic, ethylenebenzenesulfonic, methyl-ethylsulfonic, butanesulfonic, and pentafluoropropionic acids can be used for doping of POT and PDT [189]. 

Common protonic acids such as hydrochloric and sulfuric acids leave the polymer highly polar. Dopants with long polymer chains such as dodecylbenzenesulfonic acid can lessen the polar character and change the interactions of the polymer [7,15]. The effect is clearly evident from the solubility/dispersibility of polyaniline doped with dodecylbenzenesulfonic acid in nonpolar solvents such as toluene and xylene [7,16]. Certain functionalized protonic acid solutes such as camphorsulfonic acid have been shown to be highly effective in rendering the doped polymer soluble in polar organic solvents such as m-cresol [7]. 

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). 

In an important discovery in the early 1990s, Cao et al. found that organic solvent solubility can be imparted to conducting PAn salts by the incorporation of surfactantlike dopant acids (HA). For example, by doping emeraldine base (EB) with large bifunctional protonic acids such as camphor-10-sulfonic acid (HCSA) or dodecylbenzenesulfonic acid (DBSA), it is possible to solubilize fractions of these polymers in their fully doped state into solvents such a m-cresol, chloroform, toluene and xylene. This solubilization is caused by the hydrocarbon "tail" in the dopants, while the sulfonate (SO3) "head" forms an ionic bond with radical cation NH.+ sites on the PAn chains. There is some debate as to whether this approach produces true "solutions" or forms dispersions in organic media. In practical terms, the result is the same solution-processible unsubstituted conducting polymers in the doped state. 

Electrodeposition of conducting polymers on copper has been investigated by several groups, and various salts have been tested to achieve the electrochemical polymerization of pyrrole from aqueous solutions in a one-step process. No serious difficulty was found, and electrolytes used previously on iron, such as oxalic acid [115,116], salicylates [117,118], and tartrate [119] were found suitable for PPy electrodeposition on copper and its alloys aqueous phosphate solutions were also found to provide highly adherent and homogenous films [120]. In all cases, PPy electrodeposition occurred after the preliminary passivation of copper through a mixed copper salt, copper oxide, or copper hydroxide layer. A two-step process, where an oxalate-doped PPy underlayer (PPy-Oxalate) is first deposited, followed by a dodecylbenzenesulfonate-doped PPy layer... 

Three groups of plasticizing rotonating agents have been used in the preparation of a conductive composite of PANI and cellulose acetate sulfonic acids, phosphonic acids (phenyl phosphonic acid), and aliphatic diesters of phosphoric acid (dipheityl, dioctyl and dibutyl). These plasticizers improved the flexibility of the film but also significantly lowered the percolation threshold. The addition of plasticizer improves the dispersion of PANI in cellulose acetate. In this and other inventions based on the composite polymer it has been foimd to be important that the plasticizer not only helps to dissolve or soften PANI but also plasticizes the matrix polymer. In some inventions, a combination of plasticizers has been used. For example dodecylbenzenesulfonic add acted as a doping... 

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