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

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 a...

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Bibliographic Details
Published in:Langmuir 1999-02, Vol.15 (4), p.1252-1259
Main Authors: Ram, Manoj K, Salerno, Marco, Adami, Manuela, Faraci, Paolo, Nicolini, Claudio
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Miscellaneous
Organic polymers
Physicochemistry of polymers
Properties and characterization
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Summary: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.
ISSN:0743-7463
1520-5827
DOI:10.1021/la9807255