A Comparative Study of the Electrochemical Properties of Dip‐Coated, Spun, and Langmuir‐Blodgett Films of Polyaniline

Abstract

The electrochemistry of polyaniline (PANt), which has been chemically synthesized and processed in a variety of ways into thin films, has been studied, and a comparison to those properties observed in thin electrochemically grown PANt films made. In this work, PANt via solution processing has been formed into thin films using dip coating, spin coating, and the Langmuir-Blodgett (LB) technique on indium tin oxide electrodes to facilitate both cyclic voltammetry and spectroelectrochemical analysis. We find that the LB technique yields films which display the most defined voltammetric properties, although in all cases electroactivity is observed. Effects due to the residual solvent contained in the films are seen. This has enabled us to comment on the role played by the solvent molecules within the PANt matrix. Further, in the case of LP-PANi, the ultrathin films, ca. 60 A thick, as well as exhibiting excellent electrochemistry are found to be deposited in the fully oxidized, pernigraniline form of PANt, as confirmed by rest potential measurements, UV/visible and Fourier-transform infrared spectroscopy. From our results it is quite feasible to suggest that large scale electrochromie displays could be fabricated using PANt as the active material.

Multi-technique study of the anodic degradation of polyaniline films

“…Clearly, the loss of film material and/or of electrical contact to segments of the film would pose a problem for PANI films used in battery, supercapacitor, electrochromic, etc. applications [3][4][5][6][7][8], Also, the loss of film stability would be a major problem when PANI films are employed as corrosion protection coatings [9][10][11][12][13][14].…”

Electrochemistry of polyaniline Langmuir–Blodgett films

“…LB ®lm deposition of parent polyaniline employing N-methylpyrrolidone (NMP)/chloroform mixture [9,10] or pure NMP [11] as processing solvent has also been reported. While most studies report spectroscopic characterization and there is a recent report on AFM characterization [12], the electrochemical characteristics of polyaniline multilayer LB ®lms have not been given much attention [10,13,14]. We felt that such studies are of direct relevance to the performance of electronic devices based on polyaniline LB ®lms.…”

Preparation and characterization of electrically conducting Langmuir–Blodgett films of poly(N-octadecylaniline)

“…The monomer has electronic bands at 250 and 295 nm. The presence of bands at 245, 295, 304, and 918-nm in the electronic spectra of poly(Noctadecylaniline) in chloroform indicates the formation of the emeraldine salt structure of polyaniline [9]. When the polymer poly(N -octadecylaniline) is kept in dilute HCl solution overnight and its spectrum is recorded after drying and dissolving in chloroform, it shows many electronic bands at 218, 229, 241, 301, 585, 903, and 958 nm.…”

“…The conductivities in the parallel and perpendicular directions were of the order of 10 −9 and 10 −11 S cm −1 , respectively. A comparative study of the electrochemical properties of dip-coated, spin-coated, and LB film of polyaniline has been reported [9]. It was found that the LB technique yields films that display the most defined cyclic voltammetric properties.…”