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Eco-friendly inhibitors have attracted considerable interest due to the increasing environmental issues caused by the extensive use of hazardous corrosion inhibitors. In this paper, environmentally friendly PDG-g-PANI/Al2O3 composites were prepared by a low-cost inverse emulsion polymerization for corrosion inhibition of mild steel (MS) and stainless steel (SS). The PDG-g-PANI/Al2O3 composites were characterized by different techniques such as X-ray diffraction (XRD), UV/Vis, and FTIR spectroscopy. XRD measurements show that the PDG-g-PANI/Al2O3 composite is mostly amorphous and scanning electron micrographs (SEM) reveal a uniform distribution of Al2O3 on the surface of the PDG-g-PANI matrix. The composite was applied as a corrosion inhibitor on mild steel (MS) and stainless steel (SS), and its efficiency was investigated by potentiodynamic polarization measurement in a 3.5% NaCl and 1 M H2SO4 solution. Corrosion kinetic parameters obtained from Tafel evaluation show that the PDG-g-PANI/Al2O3 composites protect the surface of MS and SS with inhibition efficiencies of 92.3% and 51.9% in 3.5% NaCl solution, which is notably higher than those obtained with untreated epoxy resin (89.3% and 99.5%). In particular, the mixture of epoxy/PDG-g-PANI/Al2O3 shows the best performance with an inhibition efficiency up to 99.9% on MS and SS. An equivalent good inhibition efficiency was obtained for the composite for 1M H2SO4. Analysis of activation energy, formation enthalpy, and entropy values suggest that the epoxy/PDG-g-PANI/Al2O3 coating is thermodynamically favorable for corrosion protection of MS and exhibits long-lasting stability.

Abstract A multi-hierarchical porous polyaniline (PANI) composite which could be used in good performance pressure sensor and adjustable sensitivity gas sensor has been fabricated by a facile in situ polymerization. Commercial grade sponge was utilized as a template scaffold to deposit PANI via in situ polymerization. With abundant interconnected pores throughout the whole structure, the sponge provided sufficient surface for the growth of PANI nanobranches. The flexible porous structure helped the composite to show high performance in pressure detection with fast response and favorable recoverability and gas detection with adjustable sensitivity. The sensing mechanism of the PANI/sponge-based flexible sensor has also been discussed. The results indicate that this work provides a feasible approach to fabricate efficient sensors with advantages of low cost, facile preparation, and easy signal collection.

AbstractThe present work reports the synthesis of PANI composite with hexamminecobalt(III) chloride metal complex as dopant via in situ oxidative polymerization by ammonium persulphate in non-aqueous DMSO medium. The dopant metal complex has been synthesized by known method and characterized by using FTIR, XRD and SEM analysis. The synthesized PANI/[Co(NH3)6] Cl3 composite was characterized by FTIR, XRD, UV-Vis and SEM techniques. FTIR of PANI composite showed its successful synthesis with the presence of some dopant peaks in its FTIR spectrum. XRD spectra of composite revealed its crystalline nature having almost same spectra as that of dopant metal complex with slight shift in the position of peaks. Electrical measurement of the composite was made using four probe conductivity meter and the thermal studies have been done by thermal gravimetric (TG) technique. The results showed improvement in the thermal stability of PANI composite together with increase in its conductance, thereby making it a possible future material for high temperature application purposes. Electronic properties of the composite were investigated using UV-Vis spectroscopy which revealed decrease in the energy band gap of the composite on irradiation. This is attributed to the distortion of polymer chains on exposure to radiations, which results in decrease in conjugation and hence increases in band gap energy.