Comparative studies on Langmuir–Schaefer films of polyanilines

Langmuir isotherms of polyaniline (PANI), poly(o-toluidine) (POT), poly(o-anisidine) (POAS) and poly(o-ethoxy aniline) (PEOA) were investigated at aqueous subphase of pH 1, where doping during monolayer formation appeared as an essential step for high quality of the film. The effect of substituent groups in polyanilines plays a prominent role for the formation of Langmuir films. The area per unit repeat molecule was shown to increase by an increment of the substituent groups in polyanilines. Ultra-thin films of PANI, POT, POAS and PEOA were engineered by Langmuir–Schaefer (LS) technique. The uniformity of the deposited polyanilines LS films was verified by atomic force microscopy (AFM). The electrochemical properties of polyanilines LS films were investigated by cyclic voltammetry and current transient measurements, and the electrical characteristics were investigated by depositing the films on interdigitated electrodes. The electrochromic switching response time and diffusion coefficient of such LS films were also estimated by electrochemical surveyings.