Synthesis, characterization and physicochemical studies of copolymers of aniline and 3-nitroaniline

Polyaniline (PA), the versatile conducting polymer, owing to its tunable optoelectronic properties, facile preparation methodology and reversible redox behavior, has elicited much interest among current researchers, particularly in the fields of energy generation storage devices, protective coatings and electrochemical sensors. However, its commercialization has been much restricted due to low solution processability and thermal stability. Recent studies reveal that the above-mentioned challenges can effectively be addressed by copolymerization of PA with suitable components. In addition, the properties of copolymers could be modified and tuned by varying the monomer ratios. Thus, the present work is concerned with the fabrication of poly(aniline-co-3-nitroaniline) with varying compositions obtained by in situ oxidative copolymerization of aniline and 3-nitroaniline by altering the molar ratio of monomers. Optimization of the physicochemical properties such as UV visible absorption, solubility, thermal stability, electrical conductivity and dielectric signatures, particle size and morphology was achieved by varying the composition of monomeric substituents in these copolymers. Smoother morphology of the copolymer films was revealed by morphological studies via AFM technique and supported by particle size distribution study. The physicochemical trends demonstrated that proper proportions of nitro (NO2) group in the polymer chain are essential to achieve desired optimal physicochemical properties. Therefore, copolymers are ideally appropriate for multifaceted applications and would promote wider usage of conjugated polymers in various fields of organic-based optoelectronic as well as energy storage devices in the near future.Scopu

Properties of electrodeposited Ni-B-ZrO2 composite coatings

Ni-B coatings have high hardness and high wear resistance which make them suitable for automotive, aerospace, petrochemical, textile and electronics industries. Further improvement in properties (especially the corrosion behavior) will extend their range of applications and thus make them suitable to high wear and severe corrosion applications of oil and gas industries. Taking a note of above consideration, novel Ni-B-ZrO2 coatings were synthesized. In the present study, a comparison of properties of Ni-B and Ni-B-ZrO2 coatings in their as deposited state is presented to elucidate the effect of ZrO2 addition on structural, surface, thermal and electrochemical properties of binary Ni-B coatings. Mild steel samples were used as substrate material and the coatings were deposited through conventional electrodeposition process using dimethylamine borane (DMAB) as reducing agent. It is noticed that the addition of ZrO2 has a significant influence on crystal structure, surface roughness, thermal properties and corrosion behavior Ni-B coatings. It is noticed that Ni-B coatings are amorphous in their as deposited state while addition of ZrO2 significantly improves the crystallinity. Surface analyses confirm the formation of fine and dense structures in both Ni-B and Ni-B-ZrO2 coatings. However ZrO2 addition increases the surface roughness. The electrochemical polarization tests confirm that incorporation of ZrO2 into Ni-B matrix considerably improves the corrosion resistance due to reduction in active area of Ni-B matrix.This paper was made possible by NPRP grant # NPRP-4-662-2-249 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors. The authors also greatly acknowledge the Center for Advanced Materials (CAM), Qatar University, 2713, Doha, Qatar for permitting them to use AFM facilities.Scopu

Synthesis and properties of electrodeposited Ni-B-Zn ternary alloy coatings

Ni-B coatings have decent properties like high hardness, wear resistance and decent anti-corrosion properties which make them suitable for automotive, aerospace, petrochemical, textile and electronics industries. Despite these promising properties, further improvement in their properties is essential in order to address more challenging requirements and new developments. Taking a note of above consideration, novel Ni-B-Zn coatings have been synthesized. In the present study, a comparison of properties of Ni-B and Ni-B-Zn coatings in their as deposited state is presented to elucidate the effect of zinc addition on structural, thermal, mechanical and electrochemical properties. The coatings were deposited on mild steel substrates through conventional electrodeposition process using dimethylamine borane (DMAB) as reducing agent. The structural analyses (XRD) indicate that Ni-B coatings amorphous in as deposited condition. However, the addition of zinc to Ni-B results in improvement in crystallinity. The study of surface morphology through SEM and AFM reveals the formation of uniform, dense and fine-grained deposits in both the coatings. However, addition of Zinc increases the roughness of the Ni-B matrix. It is also noticed that nanomechanical properties of Ni-B coatings are significantly improved by the addition of zinc due to solid solution strengthening nickel-boron matrix with zinc. The electrochemical polarization tests indicate that incorporation of zinc into Ni-B matrix shifts the Ecorr and Icorr to more positive values and thus demonstrates a decent reduction in the corrosion rate of the coatings.Scopu

Corrosion behavior of electrodeposited Ni-B coatings modified with SiO2 particles

The need for coatings with improved operation is vital to insure safety and high output of industrial plants. Electrodeposition is a valuable surface modification technology that can be used to develop various kinds of coatings. Although, Ni-B coatings have good mechanical properties (hardness and wear) but are suffering from inferior corrosion resistance. The development of Ni-B composite coatings by incorporating insoluble hard particles such as metal oxides (Al2O3, TiO2 ) through electrodeposition process has generated a great interest among the research community because of auspicious improvement in properties. The main purpose of this research work was to study the influence of addition of SiO2 particles on corrosion performance of Ni-B coated surfaces which has not been reported so far. Coatings of Ni-B and Ni-B-SiO2 were deposited on steel through electrodeposition process. The microstructural (SEM) analysis confirms the formation of uniform, dense nodular structure in coatings of Ni-B and Ni-B-SiO2 . Surface examination (AFM) discloses that the addition of SiO2 increases surface smoothness. Electrochemical characterization of the synthesized coatings indicates that Ni-B-SiO2 composite coatings demonstrate better anticorrosion properties when compared to Ni-B. Enhanced corrosion performance may be ascribed to reduction in the active surface area and grain size refinement which reduces the porosity by the addition of inactive SiO2 particles.Scopu

Novel electrodeposited Ni-B/Y 2 O 3 composite coatings with improved properties

Ni-B/Y 2 O 3 composite coatings were developed through an electrodeposition process to study the effect of addition of Y 2 O 3 particles on structure, surface, thermal, mechanical, and anticorrosion properties of Ni-B coatings. It is revealed that parent crystal structure of Ni-B matrix is preserved by addition of Y 2 O 3 , however, a noticeable improvement in crystallinity is observed. The analysis of the surface exhibits formation of dense and nodular deposits in the two types of coatings, but incorporation of Y 2 O 3 particles in Ni-B matrix has resulted in a noteworthy change in grain size and surface roughness. Thermal analysis of the surfaces indicates that Ni-B-Y 2 O 3 composite coatings demonstrate superior thermal stability compared to Ni-B coatings. The nanoindentation analysis shows a significant enhancement in the mechanical characteristics of the Ni-B matrix by addition of Y 2 O 3 particles. This may be contemplated as the result of grain refinement and dispersion hardening of the Ni-B matrix by the presence of hard Y 2 O 3 particles. A decent improvement in the corrosion protection efficiency (73.6%) is also observed by addition of Y 2 O 3 particles into Ni-B matrix. Simultaneous improvement of mechanical and anticorrosion properties suggests potential applications of Ni-B-Y 2 O 3 coatings in oil and gas, automobile, and many other industries. 1 2017 by the authors.Scopu

Electrodeposited White Bronzes: A Comparison between Zn-Bearing and Zn-Free Coatings

White bronzes are ternary alloys composed of Cu, Zn and Sn, named after their bright whitish color. This class of alloys shares excellent hardness, corrosion and tarnishing resistance, and is commonly adopted in galvanic industrial processes as technological grade coatings to obtain layers with particular aesthetical and/or anticorrosive properties. Despite the widespread employment of white bronzes in fashion and the electronics industry, the recent literature lacks a characterization of these electrodeposited alloys with respect to more common binary (Cu-Sn) white bronzes. In this presentation, a thorough characterization of a commercial ternary Cu-Zn-Sn white bronze, produced by electrodeposition, is reported. Structural, chemical and physical characteristics of the deposited coating were investigated by various techniques (e.g., FIB/SEM, XPS, XRD, EDX, micro-hardness, color and corrosion tests). Results were compared with a similar set of measures obtained from a binary electrodeposited Cu-Sn white bronze (with a high tin content), in order to shed some light on the influence of Zn in the coating properties

Preparation and properties of electrodeposited Ni-B-V2O5 composite coatings

Coatings of Ni-B have gained significant importance in various industries owing to their major role in improving mechanical properties including hardness, conductivity, and wear resistance. Despite all these characteristic features, there is still the need for a lot of modifications. This is to improve the properties of the coating so as to increase their durability and overall performance. The current study is based on development of Ni-B-V2O5 composite coating on mild steel substrate through the electrodeposition technique and the investigation of mechanical and anti-corrosive properties of the formed coating. The incorporation of V2O5 particles into the composite coating was confirmed by energy dispersive spectroscopy. X-ray diffraction pattern showed amorphous nature of electrodeposited Ni-B matrix, while the crystalline nature improved with the addition of V2O5 particles to the composite. Field emission scanning electron microscopy and atomic force microscopic studies clearly indicated that the addition of V2O5 particles to the Ni-B coating increased the surface roughness. Further studies reveal increase in the micro-hardness (by 171.11%), and elastic modulus (by 9.4%) in case of the Ni-B-V2O5 composite coating relative to the Ni-B coating. The enhanced micro-hardness was attributed to the inclusion of hard V2O5 particles into the Ni-B matrix, which in turn, may inhibit the dislocation motion in the composite. An increase in corrosion resistance (by 229%) was also experienced in the electrodeposited Ni-B-V2O5 composite coating in comparison to the bare Ni-B matrix, which may be due to the masking of inert V2O5 particles on the active region of the Ni-B composite.This project was supported by the Research Groups Program (Research Group number RG-1440-070 )

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.Scopu

Thermal stability and frequency-dependent electrical conductivity of poly(aniline-co-m-nitroaniline)

Herein, we report the frequency-dependent AC conductivity of poly(aniline-co-m-nitroaniline)s which were synthesized by chemical oxidation of aniline and m-nitroaniline using ammonium persulfate as an oxidizing agent by in situ copolymerization approach. AC conductivity of the copolymers was recorded in the frequency range of 10−3 to 108 Hz. The imaginary and real part of permittivity of as-synthesized copolymers has been measured in the frequency limit of 10−2 to 107 Hz. The copolymer PA-co-m-NA20 has demonstrated very high value of permittivity than polyaniline at low frequency. At high frequency, the permittivity of the other PA-co-m-NA is almost unaltered. The SEM images manifest the unique morphology for each copolymer. The crystallinity of the copolymer samples has been studied XRD and the thermal stability of the polymers sample has been studied by differential scanning calorimetry.Funding The authors are thankful to Qatar University, for providing necessary research funding for the successful completion of the work.Scopu

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

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 limitations/implications – The conducting polymers are difficult to deposit on the metal surface because of their high dissolution tendency before the electropolymerization potential of the monomer is achieved. Practical implications – From an environmental viewpoint, poly(aniline-co-p-toluidine) is a toxic and hazardous conducting polymer. Originality/value – The paper demonstrates that poly(aniline-co-p-toluidine) showed better dispersion in different organic solvents and had higher corrosion inhibition efficiency than PAni.Scopu