Methanesulfonic acid doped

Polymer nanofiber networks consisting of achiral polyaniline were prepared by Epstein et al. (3) by oxidizing aniline with ammonium peroxydisulfate and then doping with methanesulfonic acid. 

The use of EDOT as basic units in poIy(heteroarylenemethines) has been achieved only recently. Thus, electrochemical oxidation of bis[2-(3,4-ethylenedioxy)thienyl]methane 31 led to poly(hisEDOT-methine) 32. The latter showed an electrochemical handgap of 0.4 eV based on the onset of oxidation and reduction waves while the determination of the optical handgap gave somewhat higher values [95]. Recently, the synthesis of poly(EDOT-methine) 33 was performed by the action of an excess of methanesulfonic acid on EDOT-carbaldehyde followed by the reduction of the resulting doped polymer. The related optical handgap was estimated to be around 0.95 eV [96]. 

The AMPSA-doped polyaniline fiber that was exposed 17 s in ethyl acetate coagulation bath (Table 2.7) was subsequently exposed to steam at 20 psi for 2 h to dedope the fiber and was then reprotonated by soaking the dedoped fiber in 10 wt% methanesulfonic acid in methanol for 19 h. The methanesulfonic acid was dissolved in methanol instead of water, as this improves the tensile properties of the redoped fibers. The physical properties of these fibers (Table 2.8) are important in that they show that the steam-dedoped sample is the strongest PANI fiber made in our laboratory to date, in terms of tensile strength and modulus. 

We have prepared a series of nylon / poly aniline blends using the solvent hexafluoroisdpropanol (HFIP), which is an excellent solvent for polyaniline emeraldine base (PANI-EB), polyaniline doped with various sulfonic acids (PANI-ES) and for hi molecular weight nylon 6 and nylon 12. It was observed that conductivity and morphology of the blends varied with the compatibility of the sulfonic acid anion with the nylon. Methanesulfonic acid, butane sulfonic acid dodecylbenzene sulfonic acid and camphor sulfonic acid were used as PANI dopants and the PANI-ES / nylon blends were characterized by electrical conductivity (room and low temperature) and transmission electron microscopy. The results of these various measurements and the conclusions which can be drawn regarding morphology and conductivity of Ihe blends, will be reported. 

Asensio et al. [71] also developed a method for producing acid-doped membranes by direct casting from an AB-PBI/phosphoric acid (PA)/methane-sulfonic acid (MSA) solution. The methanesulfonic acid was evaporated to produce a very homogenous, nearly transparent film with controlled composition and up to 3 moles PA/BI. This method of preparation was much more convenient than the typical multi-step, organic solvent based process. 

Gomez-Romero et al. [74] revisited the phosphomolybdic acid (PMA)-doped AB-PBI in a recent paper. They cast PMA impregnated films directly from a methanesulfonic acid (MSA) solution, and then doped the films with phosphoric acid. The AB-PBI had an IV of 2.3-2.4 dLg and the films contained up to 60 wt % PMA. It was found that a 60 wt % PMA film could be doped in a bath of up to 68% PA. The AB-PBI films dissolved when placed in higher PA bath concentrations. FTIR spectroscopy showed that the PMA and phosphoric acid were interacting with the polymer. X-ray diffraction of the polymer-acid complex indicated a quasi-amorphous structure, which is consistent with previous reports. TGA showed the membranes to be stable up to 200 °C after phosphoric acid doping, which is well within the temperature range needed to operate a PEM fuel cell. The conductivity of the... 

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