Polyaniline nanospheres

B. Sreedhar, P. Radhika, B. Neelima, N. HehaUcar, and M. V. B. Rao, Synthesis and characterization of polyaniline nanospheres, nanorods, and nanotubes-catalytic application for sulfoxidation reactions, Polym. Adv. Technol, 20, 950-958 (2008). 

The poly aniline nanospheres (PANI-NS) were synthesized by oxidative polymerization of aniline monomer at 0 °C in an ice bath using ammonium persulfate as the oxidant in the presence of surfactant. Aniline, ammonium persulfate, Polyvinylpyrrolidone, cetyl ammonium bromide, and camphorsulfonic acid are used as received from Sigma-Aldrich. Camphorsulfonic acid surfactant as the dopant and ammonium persulfate as the oxidant were used in the present synthesis of polyaniline nanospheres (see flow chart in Fig. 8.11). Calculated quantities of aniline monomer (0.005 mol) were mixed with 50 mL of distilled water and stirred using magnetic stirrer for 10 min. Meanwhile, calculated quantities of surfactant (0.75 mol) and oxidant (0.005 mol) were dissolved separately in distilled water and stirred for 10 min in an ice bath. The surfactant solution was first added to the aniline monomer aqueous solution, and then the previously cooled oxidant solution was added drop wise after which the mixture was allowed to react for 10 h in an ice bath. The precipitate was filtered and washed several times with distilled water and... 

It was found that the synthesis, as previously outlined, produced a virtually 100 % yield of polyaniline nanospheres with an average diameter of 100 nm, as can be seen in Fig. 8.12. The nanospheres are not independent of each other, but instead are agglomerated. This is to be expected as the nanospheres are produced without templating and are simply formed through a chemical method. However, the nanospheres are very uniform and possess a better morphology than the bulk PANI previously discussed. 

S.B. Han, A.L. Briseno, X. Shi, D.A. Mah, F. Zhou, Polyelectrolyte-coated nanosphere lithographic patterning of surfaces Fabrication and characterization of electropolymerized thin polyaniline honeycomb films, J. Phys. Chem. B, 106(25), 6465-6472 (2002). 

E) and (G) TEM images of the poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PAW/j-coated hollow sulfur nanospheres, respectively. Insets in E, F, G TEM images of the PPy, PEDOT, and PANI shell after dissolving sulfur with toluene, respectively. Reproduced with permission from reference Li, W., Zhang, Q., Zheng, G., She, ZW., Yao H., Cui,... 

Polyaniline (PANI) represents one of the most cited examples of nanostructured polymers, due to its outstanding electronic properties and technological applications that have promoted a wide number of studies and publications. Although a variety of different and peculiar morphologies have been reported, such as brain like [92], cauliflowers [93], nanoflakes, nanospheres and nanorods [94], chrysan-fhemum flower-like [95], plate-like structures and flower-like superstructures [96],... 

As with the bulk polyaniline sample, it was decided to perform hydrogen sorption measurements close to room temperature. Since the nanospheres do not contain any hydrogen after synthesis, with the exception of the chemically bonded hydrogen that is part of the polyaniline chemical structure, the first hydrogen measurement performed was absorption. The sample was kept under vacuum and then exposed to 80 bar of hydrogen pressure. Each absorption measurement was then followed by a desorption measurement at 30 °C and given enough time to reach an equilibrium. The results of the kinetic absorption and desorption measurements are shown in Fig. 8.14. 

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