Nanostructured Growth Patterns and Chaotic Oscillations in Potential during Electropolymerization of Aniline in the Presence of Surfactants

Abstract

Polyaniline nanoparticles were synthesized by simple electrochemical polymerization of aniline in systems (a) aniline-sodium dodecyl sulfate (NaDS)-dodecylbenzene sulfonic acid (DBSA)-H(2)O and (b) aniline-NaDS-DBSA-cetyltrimethyl ammonium bromide (CTAB)-H(2)O. Different morphologies including compact and fractal/dendrimer were observed at different experimental conditions. Fractal dimension was calculated by the box counting method. Growth kinetics during electropolymerization of aniline in both of the systems was studied by measuring the weight of polymer aggregates as a function of time. Growth rate was found to be reduced in system (b) due to coordination of CTAB with the growing polyaniline chain. The weight of polymer aggregates was found to depend on field intensity and attains a maximum value at a critical field intensity 4.0 V/cm. Beyond this critical field intensity, the growth rate was decreased due to loss of conjugation and degradation of the polymer backbone. Electropolymerized aggregates were characterized by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and electrical conductivity measurements. Nanosized polyaniline was formed, with particle diameters in the range of 10-200 nm, as evident by TEM studies and supported by XRD studies. FT-IR spectroscopy established the formation of hyperbranched polyaniline chains. During electropolymerization, oscillations in potential were monitored as a function of time at different experimental conditions. A suitable mechanism for fractal growth of polyaniline was also proposed.

Permselectivity and thickness-dependent ion transport properties of overoxidized polyaniline: a mechanistic investigation

“…However, surfactants such as SDS play a dual role (surfactant and electrolyte) during the polymerization of aniline. 35,36 The counter anions of the surfactant (SDS) act as dopants during the polymerization process and due to their larger sizes, the polymerization is slower here in comparison with other strong acids. However, the use of SDS leads to effective overoxidation.…”

Fractal Reconstruction of Microscopic Rough Surface for Soot Layer during Ceramic Filtration Based On Weierstrass–Mandelbrot Function

“…Generally speaking, the previous works in literatures suggest that boxcounting FD algorithm is an effective method to handle the image segmentation details. 26 Accordingly, it is feasible to model rough surface with the FDs determined by a boxcounting approach.…”

“…To achieve the FDs from the extremely disordered morphology, it is necessary to utilize an appropriate fractal approach. Generally speaking, the previous works in literatures suggest that box-counting FD algorithm is an effective method to handle the image segmentation details . Accordingly, it is feasible to model rough surface with the FDs determined by a box-counting approach.…”

Controlled electrochemical synthesis of conductive nanopolypyrrole and its application in the design of a solid‐state ion sensor

“…The morphology is an important factor that influences the characteristics and performance of conductive polymers. Fractal structures are generally observed in nonequilibrium growth processes, such as electrodeposition, crystal growth, electropolymerization, and chemical dissolution, and also in biological systems, such as bacterial growth . The incorporation of a surfactant into a conducting PPy synthesized in the presence of copper salt is likely to improve the morphology, electrical conductivity, particle size, and ion‐sensing behavior and can be used in the construction of solid‐state ion‐selective electrodes .…”