Umesh S. Waware

Polyaniline/Palm Oil Blend for Anticorrosion of Mild Steel in Saline Environment

The corrosion protective performance of polyaniline/palm oil (PAni-PO) blend coated on mild steel in 3% NaCl aqueous solutions has been evaluated by electrochemical methods, namely, open circuit potential (ocp), potentiodynamic polarization, and EIS spectroscopy. The surface of mild steel was covered by a dark green protective layer due to the physical interaction between the coating and steel. The permanent shifts of ocp and potentiodynamic polarization towards higher positive value of oxidation potential by about 800 mV and by a decrease in corrosion current density by sixfold in magnitude and an increase of 10 orders of magnitude in charge transfer resistance are due to protective coating.

Synthesis and characterization of electrically conductive poly(aniline-co-3-bromoaniline) nanocomposites

Poly(aniline-co-3-bromoaniline) copolymers with varying compositions of the monomers have been prepared in this work by copolymerization of aniline and 3-bromoaniline using ammonium persulphate as oxidant. Structure and morphology of the copolymers have been characterized by XRD, 1H-NMR, UV–Vis, SEM and TEM. Though polyaniline consists of aggregates of nanoparticles, poly(3-bromoaniline) shows plate-like morphology. The copolymers were found to exhibit mixed morphology depending on the composition. Electrical properties such as AC conductivity and dielectric permittivity of the different polymers have been investigated. Conductivity studies reveal that the AC conductivity of the polymers depend on their composition. The poly(3-bromoaniline) shows a conductivity of the order of 10−8 S/cm which is much lesser than polyaniline. However, copolymerization of polyaniline with 10% 3-bromoaniline resulted in a few-fold increase of the conductivity compared to pure polyaniline.

Synthesis and characterization of electrically conducting copolymers of poly(aniline-co-o-iodoaniline)

Functionalized copolymers of poly(aniline-co-o-iodoaniline) have been synthesized by the chemical oxidative polymerization method by using o-iodoaniline (o-IA) and aniline (AN) as monomer units by changing their molar feed ratio in acid aqueous medium. The physical properties viz; solubility, electrical conductivity have been studied to characterize them. The copolymers possess better solubility than unsubstituted homopolymer in organic solvent such as N-methyl-2-pyrrodinone (NMP). The conductivity of the pressed pellets of as-synthesized copolymers depends upon the content of o-IA in the polyaniline (PANI). The structural confirmation of the copolymer has been explained by Fourier transform infrared spectroscopy study which suggest that AN and o-IA units are uniformly distributed along the polymer chain and thus, the physical properties of copolymers may possibly be tailored by varying the molar feed ratio in copolymerization reactions. The conductivity of the copolymer decreases upon increasing the o-IA content in molar feed, because the introduction of –I- as a functional group reduces the extent of conjugation of the polymer chain.

Electropolymerization of poly(aniline-co-p-toluidine) on copper and its application as a corrosion inhibitor

Purpose – This paper aims to compare the inhibitive effects of polyaniline (PAni), poly(p-toluidine) and poly(aniline-co-p-toluidine) in hydrochloric acid (HCl) solution. Design/methodology/approach – The electrochemical deposition of PAni, poly(p-toluidine) and poly(aniline-co-p-toluidine) on pure copper metal was studied potentiodynamically. The copolymer deposited was characterized by Fourier transform infrared (FTIR) spectroscopy, ultraviolet (UV)-visible spectroscopy and scanning electron microscopy (SEM). The corrosion inhibition studies on copper electrode were performed using electrochemical methods, viz, open circuit potential (OCP) measurements, potentiodynamic polarization scans and electrochemical impedance spectroscopy (EIS) tests, conducted in 0.1 M HCl solution. Finding – The results of the study reveal that the copolymer of poly(aniline-co-p-toluidine) at the optimum concentration of 1 × 10−3 M has better corrosion inhibition efficiency as compared to PAni and poly(p-toluidine). Research l...

Synthesis and Characterization of Polyaniline, Poly(3-fluoroaniline), and Poly(aniline-co-3-fluoroaniline) Derivatives Obtained by Chemical Oxidative Polymerization Methods

ABSTRACT The syntheses of thermally stable, conducting polyaniline, poly(3-fluoroaniline), and poly(aniline-co-3-fluoroaniline) derivatives by chemical oxidative polymerization methods are described. By varying the mol% of 3-fluoroaniline in the monomer feed, a series of new poly(aniline-co-3-fluoroaniline) derivatives with different chemical compositions were prepared by chemical oxidative copolymerization methods using ammonium persulfate as oxidant in the presence of hydrochloric acid as the dopant. The chemical oxidative copolymerization of aniline with 3-fluoroaniline affords poly(aniline-co-3-fluoroaniline) derivatives with increased solubility properties, greater thermal stability, improved morphological control, and enhanced electrical characteristics, which promotes the processibility of the different fluorine-functionalized polyaniline derivatives when compared with the parent polyaniline homopolymer. Poly(3-fluoroaniline) and the different poly(aniline-co-3-fluoroaniline) derivatives show better solubility and thermal stability than the polyaniline homopolymer, due to the incorporation of the F atoms along the fluorine-functionalized polyaniline backbone. Furthermore, the poly(3-fluoroaniline) homopolymer is thermally more stable than the polyaniline homopolymer due to the presence of the C–F bonds of the 3-fluoroaniline units along the polymer backbone. The electrical conductivity of the different poly(3-fluoroaniline) derivatives is dependent on the 3-fluoroaniline content in the polymer derivative and the morphology of the specific copolymer. The poly(3-fluoroaniline) homopolymer exhibits the lowest electrical conductivity. In addition, the electrical conductivity of the different poly(aniline-co-3-fluoroaniline) derivatives decreases with increasing 3-fluoroaniline content in the copolymer. The different polymer derivatives were characterized by proton nuclear magnetic resonance (1H NMR) spectrometry, fourier transform infrared (FTIR) spectroscopy, ultraviolet visible (UV–Vis) spectroscopy, thermogravimetric analyses, scanning electron microscopy, and electrical conductivity measurements. GRAPHICAL ABSTRACT

N-cetyl-N,N,N trimethyl ammonium bromide (CTAB)-stabilized polyaniline: a corrosion inhibitor for mild steel

Purpose The purpose of this study is to compare the inhibitive effect of polyaniline (PAni) and N-cetyl-N,N,N trimethyl ammonium bromide (CTAB)-stabilized PAni in a hydrochloric acid (HCl) medium. Design/methodology/approach PAni has been deposited potentiodynamically on mild steel in the presence of CTAB as a stabilizing agent to achieve high corrosion inhibition performance by the polymer deposition. The corrosion inhibition studies of CTAB-stabilized PAni inhibitor in 0.1 M HCl acidic solution was carried out by electrochemical methods, namely, open-circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy technique. Findings The results of electrochemical studies have shown that the CTAB-stabilized PAni inhibitor has higher corrosion efficiency than PAni on mild steel in 0.1 M HCl solution. The maximum per cent efficiency evaluated using the potentiodynamic polarization method is approximately 91.9. Originality/value CTAB-stabilized PAni has never been studied as a corrosion inhibitor for mild steel in an acidic medium. The investigations demonstrate relatively the better corrosion inhibition efficiency and high dispersion of the polymer in the acidic medium.

Synthesis and characterization of electroactive novel poly-2-cynoaniline

Uniform needle-like structures of poly-2-cynoaniline are formed without the use of any template by electrochemical oxidative polymerization method on copper electrode in acidic medium. The structural characterizations are performed by FT-IR, UV-Visible spectroscopy and X-ray diffraction studies. The morphology of the polymer is demonstrated by scanning electron microscopy (SEM). The framework of the needle-like structure, which is seen at low and high magnifications appeared as nanorods of 50–80 nm diameter and of length up to a few micrometres to form a scaffold of interconnected nanorods. Thermogravimetic analysis (TGA) indicates that poly-2-cynoaniline is thermally more stable than polyaniline. The conductivity of pressed pellet of the as-synthesized polymer measured at room temperature of 25 °C by four-probe measurement method was found to be 9.1824 × 10−5 S/cm. The polymer is easily dispersed in some organic solvents and shows high solubility.

Towards the higher solubility and thermal stability of poly(aniline-co-m-bromoaniline)

In the current study, we have described the synthesis and the physical properties of poly(aniline-co-m-bromoaniline) conducting copolymers. The copolymers of different composition are essentially obtained by varying the molar feed ratio of the two monomers. The higher solubility of the copolymers could be procured as compared to polyaniline (PA) in different solvents. The electrical conductivity has been studied by two-probe method; at room temperature, the conductivity of the copolymer decreases upon increasing the molar ratio of m-bromoaniline monomer. The introduction of bromine (–Br) group reduces the degree of conjugation in the polymer chain. Thus, conduction of electrons is prohibited along the conjugated system. In the thermogravimetric analysis (TGA), a three-stage decomposition of the copolymer has been observed. The copolymers of poly(aniline-co-m-bromoaniline) are thermally stable at high temperature. The composition of the copolymer has been confirmed from the binding energies of C–C, C–N, and C–Br in the XPS study.

Manufacture and Properties of Ni-B-Fe 2 O 3 Composite Nano-coatings by Electrodeposition

Present study deals with electrodeposition of binary Ni-B and ternary Ni-B-Fe2O3 alloy coatings using DMAB as a source of boron. The coatings were characterized for elemental composition, phase composition and surface topography using FE-SEM, XRD and Atomic Force Microscopy (AFM). The phase stability of coatings was studied using differential scanning colorimetry (DSC). Subsequently, the mechanical and electrochemical corrosion studies were carried out using nano indentation and potentiodynamic polarization studies respectively. The results indicate that addition of Fe2O3 in Ni-B alloy coatings results in 52% improvement in hardness and 3 times improvement in corrosion protection efficiency over Ni-B coatings. Ni-B-Fe2O3 coatings can be suitable economical option towards conventional electroless Ni-B alloy.

Newly Developed Nickel-Boron Composite Surface Coatings with Pd Particles: Structural, Mechanical and Corrosion Properties

Ni-B and Ni-B-Pd composite coatings have been electrodeposited from an aqueous electrolyte using direct current. The Ni-B composite coating has been observed to be dense, smooth, and shows a globular, cluster of grains type morphology. On the other hand, the Ni-B-Pd composite coating is observed to be porous, highly rough and shows stacked crystal type morphology. The addition of palladium has significantly improved the crystallite size of the coating. From DSC analysis, it is observed that the Ni-B-Pd composite coating is thermodynamically more stable than the Ni-B composite coating. In spite of larger grain size and higher roughness the Ni-B-Pd coating is observed to exhibit higher hardness (≈40% higher) and elastic modulus (≈70% higher) than that of the Ni-B composite coating. Also, it has been observed to possess better protective property (almost three times) than that of the Ni-B composite coating.