Synthesis of polypyrrole/Ni-doped TiO 2 Nanocomposites (NCs) as a protective pigment in organic coating

This study reports the synthesis of polypyrrole/Ni-doped TiO 2 nanocomposites (NCs) as a protective pigment in organic coatings. Polypyrrole/Ni-doped TiO 2 NCs were prepared by in situ chemical oxidative polymerization of pyrrole monomer in the presence of Ni-doped TiO 2 nanoparticles (NPs) with ammonium persulfate (APS) as oxidant. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) result show a core-shell structure of the pigments. The XRD results indicate that the average crystalline size of Ni-doped TiO 2 NPs is larger than TiO 2 NPs while the sizes of polypyrrole/TiO 2 NCs and polypyrrole/Ni-doped TiO 2 NCs were 93.46 ± 0.06 and 26.16 ± 0.06 nm respectively. Hence the thickness of the shell in the core-shell incorporating the Ni-doped/TiO 2 NPs was very thin and the area of synthesized PPy is increased. The electrochemical impedance spectroscopy (EIS) results show that increasing the area of synthesized polypyrrole in the presence of Ni-doped-TiO 2 NPs can increase its ability to interact with the ions liberated during the corrosion reaction of steel in the presence of NaCl. © 2010 Elsevier B.V. All rights reserved

Electrodeposition Of (Pyrrole-Co-Phenol) On Steel Surfaces In Mixed Electrolytes Of Oxalic Acid And DBSA

Poly (pyrrole-co-phenol) (co-PyPh) was synthesised using cyclic voltammetry in the mixture of dodecyl benzene sulphonic acid (DBSA) with oxalic acid solution on steel electrodes The morphology and compositions were characterized by Field Emission Scanning Electron Microscopy (FESEM) Fourier Transform Infrared Spectroscopy (FTIR) techniques and Energy-dispersive X-ray spectroscopy (EDX) Electrode/co-PyPh/electrolyte system was studied in 0 1 M NaCl solutions by Electrochemical Impedance Spectroscopy (EIS) The Warburg impedance observed in mid frequency region is an evidence of the effective barrier behaviour of coating The results of EDX indicate that the content of doped sulphur can influence the morphology of co-PyPh Three dissimilar morphologies of co-PyPh and different amount of doped sulphur in co-PyPh are observed The existence of phenol monomer leads to a decrease in the amount of doped sulphur in co-PyPh compared with synthesised polypyrrole (PPy) in the same environment (c) 2010 Elsevier B V All rights reserve

Comparison of corrosion protection between double strands of polyaniline and poly-o-anisidine with poly(Acrylic Acid-Co-Acryl Amide) on steel

Double strands of polyaniline (PAn) and poly(o-anisidine) (POAn) with poly(acrylic acid-co-acryl amide) (PAA-co-AA) were successfully prepared on steel as undercoating, by immersion of the pretreated surfaces into a PAn: (PAA-co-AA) and POAn: (PAA-co-AA) saturated DMF solution separately. The undercoatings formed on the steel were characterized by Fourier transform infrared spectroscopy (FTIR) techniques. A commercial paint (Nippon Paint, nonadded Chrome) was used as topcoating. Electrode/electroactive polymer/paint/electrolyte system was studied by electrochemical impedance spectroscopy (EIS). The EIS studies show that during the first 18 days immersion time in 3.5% solution of NaCl, paint/PAn coating has better corrosion resistance than paint/POAn coating while in the final week of immersion time, the pore resistance (R-po) and coating capacitance (C-c) of paint/POAn are higher and lower than the paint/PAn, respectively

Synthesis and characterization of poly(N-methylpyrrole)/TiO2 composites on steel

Poly(N-methyl pyrrole) coating was successfully electrodeposited on steel substrates in mixed electrolytes of dodecyl benzene sulphonic acid (DBSA) with oxalic acid in the absence and the presence of TiO2 nanoparticles (NPs). The morphology and compositions were characterized by Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), Energy-Dispersive X-ray spectroscopy (EDX). X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) were used to calculate the size of nanoparticles. Electrode/polymer/electrolyte system was studied by Electrochemical Impedance Spectroscopy (EIS). The FESEM micrographs suggest that the incorporation of TiO2 nanoparticles affects the morphology of the film significantly and makes the TiO2 to be loosely piled up with PMPy. The results of EIS showed that synthesized PMPy in the presence of TiO2 NPs increases and decreases the R-po and C-c of the coating respectively. The increase of the area of synthesized PMPy in the presence of nanoparticles can increase its ability to interact with the ions liberated during the corrosion reaction of steel in NaCl solution. (C) 2010 Elsevier B.V. All rights reserved

Effect of narrow diameter polyaniline nanotubes and nanofibers in polyvinyl butyral coating on corrosion protective performance of mild steel

This study shows the effect of narrow diameter polyaniline (PAn) nanotubes and nanofibers in polyvinyl butyral coating on corrosion protective performance of mild steel. The PAn nanotubes and nanofibers were synthesised by chemical oxidative polymerisation in the presence of dodecylbenzene sulfonic acid (DBSA) as a bulky dopant acid. The molar ratios of monomer to DBSA used for the nanotube and the nanofiber synthesis are 1:1 and 4:1, respectively. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results confirm the narrow diameter range of 180-230 nm for the PAn nanotubes and nanofibers. Electrochemical impedance spectroscopy (EIS) confirms that the resistance of the coating containing PAn nanotubes is three times higher than the coating containing PAn nanofibers after 30 days of immersion. This effect can be explained because of the higher surface area of the nanotubes compared to nanofibers with the same mass. This difference increases the ability of PAn to interact with the ions liberated during the corrosion of the steel and increases the rate of cathodic reduction of oxygen on the surface of PAn. © 2012 Published by Elsevier B.V. All rights reserved

The electrical properties of a sandwich of electrodeposited polypyrrole nanofibers between two layers of reduced graphene oxide nanosheets

A sandwich of polypyrrole (PPy) nanofibers between two electrodeposited reduced graphene oxide (RGO) layers was prepared by an electrochemical method. The structure and compositions were characterised by field emission scanning electron microscopy (FESEM) and Fourier transform infrared (FT-IR) spectroscopy. The electrical properties were studied by electrochemical impedance spectroscopy (EIS). The FESEM results confirmed synthesis of a sandwich structure with PPy nanofibers between two electrodeposited RGO layers (RGO/PPy/RGO). The mean width of PPy nanofibers was approximately 76 +/- 16 nm. The EIS results showed that the charge transfer resistance of the coated glassy carbon electrode (GCE) with a sandwich structure of RGO/PPy/RGO was significantly decreased in comparison with coated GCE with PPy nanofibers. This was because the RGO with many small band gaps is more favourable for electron conduction. The comparison of EIS results shows that diffusion of active species through the RGO layers is increased in the presence of the second layer of RGO. The simulation results indicate a high interfacial capacitance (C-dl) of 2170.60 mu F cm(-2) for the coated GCE with RGO/PPy/RGO compared with 360.77 mu F cm(-2) for coated GCE with PPy/RGO. This difference in capacitance can be attributed to the highly accessible specific surface area of graphene and its high efficiency towards electrolyte ion absorption. (C) 2012 Elsevier Ltd. All rights reserved

Preparation of ultra-thin polypyrrole nanosheets decorated with Ag nanoparticles and their application in hydrogen peroxide detection

This study examines the preparation of ultra-thin polypyrrole nanosheets decorated with Ag nanoparticles (Ag-UTPNSs) and their application in the enzyme-less detection of hydrogen peroxide (H2O2) detection. The X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results confirmed that Ag nanoparticles (NPs) were deposited onto the surface of the UTPNSs. The increase of the H2O2 reduction current peak to 120 mu A in the presence of the Ag-UTPNS/glassy carbon electrode (GCE) as compared to the UTPNS/GCE indicates that the sensitivity of the electrode to H2O2 is significant. This observation can be explained by the larger surface area of the UTPNSs, which can increase the interactions between the polymer and the AgNO3 solution during the deposition of the Ag NPs, and by the small size of the deposited Ag NPs, which can produce a surface area of Ag that is suitable for the reaction with H2O2. The amperometric responses show that the limit of detection, the limit of quantification (S/N = 3) and the sensitivity are estimated to be 0.57 mu M, 1.93 mu M and 4.477 mu A mM(-1), respectively, for the linear segment. The results of the reproducibility experiments show that the use of Ag-UTPNS/GCE is feasible for the quantitative detection of certain concentration ranges of H2O2. (C) 2012 Elsevier Ltd. All rights reserved

Evaluation of nickel-cobalt deposition through the electrochemical impedance spectroscopy under magnetic field

Based on a dilute Watts bath, a nickel-cobalt electrolyte was formulated and its performance studied using Electrochemical Impedance Spectroscopy. The impedance spectrum is shown for electrodeposition at-0.9V and-I.IV in the presence of a permanent magnet field applied parallel to the cathode surface at a strength of 9T and in its absence. In the presence of such a magnetic field, a deposit with more uniform morphology was formed. Changes in deposit properties become less significant in the presence of AC, but even here, an effect is observed. Deposit properties were studied using SEM and AFM

Effects of different polypyrrole/TiO2 nanocomposite morphologies in polyvinyl butyral coatings for preventing the corrosion of mild steel

This study addresses the synthesis and comparison of the corrosion protective properties of two different polypyrrole/TiO2 nanocomposite (PPy/TiO2 NC) morphologies in a polyvinyl butyral coating on mild steel. The polymerization was performed via low-temperature in situ chemical oxidative polymerization in the presence of methyl orange (MO) and dodecyl benzene sulfonic acid (DBSA). The field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results show two different spherical and tube shapes in the core-shell structure of the PPy/TiO2 NCs synthesized in the presence DBSA and MO, respectively. The TEM results indicate that a thinner polypyrrole (PPy) shell is synthesized on the PPy/TiO2 NCs in the presence of MO than that synthesized in the presence of DBSA. Thermogravimetric analysis (TGA) results indicate that the mass percentages of the TiO2 NPs in the PPy/TiO2 NCs synthesized in the presence of MO and DBSA are 29.71 and 33.84%, respectively. The PPy/TiO2 NCs synthesized in the presence of MO were found to yield better anti-corrosion performance than those synthesized in the presence of DBSA. This result is due to the effect of the PPy surface area, which has more influence over corrosion control than the percentage of TiO2 nanoparticles in the nanocomposites. © 2012 Elsevier B.V. All rights reserved

Synthesis and characterization of polypyrrole/Sn-doped TiO2 nanocomposites (NCs) as a protective pigment

We have chemically polymerized pyrrole in the presence of Sn-doped TiO2 nanoparticles (NPs) and TiO2 (NPs) which act as a protective pigment. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) results show a core-shell structure of pigments in which TiO2 and Sn-doped TiO2 NPs have a nucleus effect and caused a homogenous PPy core-shell type morphology leading to coverage of the TiO2 and Sn-doped TiO2 NPs by PPy deposit. The XRD results indicate that the crystalline size of polypyrrole/TiO2 NCs and polypyrrole/Sn-doped TiO2 NCs were approximately 93.46 +/- 0.06 and 23.36 +/- 0.06 nm respectively. The electrochemical impedance spectroscopy (EIS) results show that the performance of polypyrrole/Sn-doped TiO2 NCs is better than polypyrrole/TiO2 NCs. The results indicate that increasing the area of synthesized polypyrrole in the presence of Sn-doped TiO2 NPs can increase its ability to interact with the ions liberated during the corrosion reaction of steel in the presence of NaCl. The UV-vis results show that the band gap of TiO2 NPs increases with doped of Sn in lattice of TiO2. The increase of the band gap of TiO2 with doping of Sn can decrease the charge transfer through the coating. (C) 2011 Elsevier B. V. All rights reserved