Anilines polymeric

The AES results indicate that the aniline coverage is more than two times greater than the maximum coverage based on van der Waals radii. The TPR results show this species is too stable to be a condensed multilayer. Hence, we conclude that aniline polymerized forming a very stable polymer layer. In addition, the absence of infrared bands corresponding to C=C stretches or ring vibrations indicated that the poly(aniline) film was formed with the phenyl rings parallel to surface. The infrared results also indicated that the poly(aniline) film had N-H bonds which were oriented perpendicular relative to the surface. 

Aniline polymerized differently from the other heteroaromatics as it retained a parallel bonding configuration for the rings. The NH2... 

Aromatic molecules can be polymerized catalytically on clean metal surfaces, or electrochemically to produce oriented polymer films. Initial adsorption of aromatic molecules occurs by electron donation from the aromatic molecule to the surface. This electron donation creates radical cations that can polymerize. Molecular orientation in the films depends on the stable bonding configuration of the radical cation. Thiophene, pyridines, and pyrrole all polymerize with the ring substantially perpendicular to the surface, whereas aniline polymerizes with the phenyl rings parallel to the surface. The catalytically... 

Feng W, Bai XD, Lian YQ, Liang J, Wang XG, Yoshino K (2003). Well-aligned polyaniline/car-bon-nanotube composite films grown by in-situ aniline polymerization. Carbon 41 1551-1557. 

Figure 2. Proposed aniline polymerization mechanism R = H for PANI otherwise a derivative when substituted monomers are used. The allowed Y values are 0, 0.5 and 1.

Palladium catalysts with diimine ligands based on 2,6-diisopropyl aniline polymerize ethene to a rubbery, highly branched polyethene with low glass transition temperatures [12 a]. The interest in these materials results from their possible appheation as a rubber modifier in engineering plastics [3j,k]. However, the activity of the palladium catalysts is not satisfactory for technical use in a world scale plant We intended to improve the activity by increasing the Lewis acidity of the metal center by using relatively electron-deficient bromo phenyl diimine hgands. 

The nature and concentration of the protonic acid (HA) employed in aniline polymerization with S2082- have a significant effect on the physicochemical properties... 

Zotti el al. [43,93] carried out extensive studies on the role of anions in the aniline polymerization. According to them, the total deposition charge (Qe) of the PAn has an expression. 

W. Feng, X. D. Bai, Y. Q. Lian, J. Liang, X. G. Wang, and K. Yoshino, Well-aligned polyani-line/carbon-nanotube composite films grown by in-situ aniline polymerization Carbon, 41, 1551-1557 (2003). 

Figure 8.6 U V-vis-NIR spectra of solutions of Janus Green B azo dye in NMP (A), and aqueous acidic solution (B), and resonance Raman spectra of Janus Green B azo dye in the solid state obtained at the indicated exciting radiations. The dye molecular structure is also shown. (Reprinted with permission from Macromolecules, Aniline Polymerization into Montmorillonite Clay A Spectroscopic Investigation of the Intercalated Conducting Polymer by G. M. do Nascimento, V. R. L. Constantino, R. Landers and M. L. A. Temperini, 37, 25. Copyright (2004) American Chemical Society)...

G.M. Do Nascimento, V.R.L. Constantino, R. Landers, and M.L.A. Temperini, Aniline polymerization into montmorillonite clay a spectroscopic investigation of the intercalated conducting polymer. Macromolecules, 37, 9373-9385 (2004). 

Illustration of this effect in the case of a two-step process for aniline electropolymerization on mild steel and zinc from an aqueous electrolyte was reported by Lacroix et In acidic medium (the usual conditions for the electrodeposition of PANI) the direct electropolymerization of aniline on zinc or steel fails, because large amounts of metal dissolve before the aniline polymerizes. This can be avoided if the surface is first treated by depositing a thin polypyrrole film in neutral salicylate medium. This PPy layer behaves as a thin noble-metal layer and can be used for the electrodeposition of a PANI film of controllable thickness in an acidic medium. Using this pretreatment, no or very little metal dissolution occurs in this second step. The films exhibit very stable electroactivity in acidic electrolytes, similar to that of PANI deposited on platinum, which indicates that the underlying oxidizable metal is fully protected (Figure 16.1). 

Planes, G. A., J. L. Rodriguez, M. C. Miras, G. Garcia, E. Pastor, and C. A. Barbero. 2010. Spectroscopic evidence for intermediate species formed during aniline polymerization and polyaniline degradation. Physical Chemistry Chemical Physics 12 10584-10593. 

Using functional molecules as structural directors in the chemical polymerization bath can also produce polyaniline nanostructures. Such structural directors include surfactants [16-18], liquid crystals [19], polyelectrolytes (including DNA) [20,21], or complex bulky dopants [22-24]. It is believed that functional molecules can promote the formation of nanostructured soft condensed phase materials (e.g., micelles and emulsions) that can serve as soft templates for aniline polymerization (Figure 7.3). Polyelectrolytes such as polyacrylic acid, polystyrenesulfonic acid, and DNA can bind aniline monomer molecules, which can be polymerized in situ forming polyaniline nanowires along the polyelectrolyte molecules. Compared to templated syntheses, self-assembly routes are more scalable but they rely on the structural director molecules. It is also difficult to make nanostructures with small diameters (e.g., <50 nm). For example, in the dopant induced self-assembly route, very complex dopants with bulky side groups are needed to obtain nanotubes with diameters smaller than 100 nm, such as sulfonated naphthalene derivatives [23-25], fidlerenes [26], or dendrimers [27,28]. 

One can safely say that aniline polymerization involves progressive nucleation with a two-dimensional growth mechanism at low monomer concentration. Instantaneous nucleation leads to the formation of an inhomogeneous material where phases segregate into protonated metallic islands embedded in a sea of insulating islands. This microscopic non-uniformity sometimes develops into macroscopic morphology which will not be reflected significantly in the peak... 

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