Physical Properties of Polyaniline Films:  Assembled by the Layer-by-Layer Technique

Abstract

Sequential addition of a polyanion, poly(styrene sulfonate), and a polycation, polyaniline, lead to the formation of layer-by-layer films at different solid surfaces. The prime variables which determine the films formation of poly(styrene sulfonate) (PSS)/polyaniline (PANI) were the polymer charge and ionic strength. The films were deposited by selecting organic/inorganic acid media at pH 2.8. The building up of such multilayer films was characterized by the increment of the adsorbed amount through UV−visible spectroscopy. A linear increase in the absorption magnitude was measured from 1 to 25 bilayers. The uniformity of the PSS/PANI layer-by-layer (LBL) films could be well-maintained, undoping the films in NaOH for obtaining an emeraldine base form of polyaniline. The built-up multilayers were investigated by atomic force microscopy, scanning tunneling microscopy, and cyclic voltammetric and electrical conductivity measurements. The interesting feature of the nearly equal grain size was noticed between 4 and 15 bilayer films of PSS/PANI. The surface roughness was distinguished beyond 15 bilayers of LBL films. The cyclic voltammogram showed the change in the peaks potential value going from 1 to 20 bilayers. The inhomogeneity incorporated inside the films slowed down the electrochemical kinetics in the PSS/PANI bilayers while going from 1 to 25 bilayer films. The diffusion coefficient (D 0) of PSS/PANI 10 bilayers was estimated to be 2 × 10-8 cm2 s-1. Such multilayer films exhibit conductivity in the area of 0.1 S/cm.

Self-assembly of mono- and multilayers of polyconjugated conducting polymers

“…A paper devoted to the physical properties of PANI 38/ PSS multilayers has recently appeared 66) . The films were deposited by selecting organic/inorganic acid media at pH of 2.8.…”

Evaluating the chemio-physio properties of novel zinc oxide–polyaniline nanocomposite polymer films

“…1 The fabrication of nanocomposite films by wet chemical techniques has been proven to be a more simple and inexpensive strategy than technologically demanding physical methods. 2 Recently, Ram et al [3][4][5][6][7][8] developed metal oxide and conducting polymer nanocomposite films of TiO 2 -PANI, TiO 2 -polypyrrole, SnO 2 -polyhexylthiophene, TiO 2 -poly (thiopheneaniline) nanocomposite, Mn-Ferrite-PANI and MWCNT-poly (o-anisidine) using wet chemical methods and used them extensively in gas sensing and molecular electronics applications. PANI is one of the most widely studied materials because of its unique electrochemical, chemical and physical properties.…”

Caracterização elétrica de filmes ultrafinos de PANI/PVS: material potencial para detecção de amônia em galpões de criação avícola

“…Observa-se nessa figura que a intensidade da absorção aumenta com n em todo o espectro e seu máximo ocorre em torno de 900 nm. A partir desse resultado foi traçado um gráfico da intensidade da absorção em 900 nm vs. n, Figura 2b, e observado sua dependência linear, garantindo que a adsorção dos filmes ocorreu como esperado [12] . As imagens de AFM de filmes Lbl de PANI/PVS apresentadas na Figura 3 mostram a superfície da topografia das amostras contendo 1, 4 e 10 bicamadas, depositados sobre substrato de vidro cuja rugosidade média quadrática é da ordem de 3,3 nm.…”