Project description:Chromate free corrosion inhibitors are searched for to mitigate the economic loss caused by mid-steel corrosion. Here, we show metal-free organic inhibitors having free coumarate anions that can be used either as direct corrosion inhibitors or incorporated into a polymer coating obtained by UV-curing. Four different ionic liquid monomers and polymer coatings with hexoxycoumarate anion and different polymerizable counter cations were investigated. Potentiodynamic polarization, electrochemical impedance spectroscopy, and surface analyses have verified their corrosion inhibition performance on a mild steel AS1020 surface. In the case of the coumarate ionic liquid monomers, the most promising inhibitor is the one coupled with the ammonium cation, showing an inhibition efficiency of 99.1% in solution followed by the imidazolium, pyridinium, and anilinium. Next, the ionic liquid monomers were covalently integrated into an acrylic polymer coating by UV-photopolymerization. In this case, the barrier effect of the polymer coating is combined with the corrosion inhibitor effect of the pendant coumarate anion. Here, the best polymer coatings are those containing 20% imidazolium and pyridinium cations, presenting a greater impedance in the EIS (Electrochemical Impedance Spectroscopy) measurements and less evidence of corrosion in the scribe tests. This article shows that the cationic moiety of coumarate based ionic liquids and poly(ionic liquid)s has a significant effect on their excellent corrosion inhibition properties for a mild steel surface exposed to aqueous chloride solutions.
Project description:In this contribution, we report the facile preparation of cross-linked polymerizable ionic liquid (PIL)-based nanoparticles via thiol-ene photopolymerization in a miniemulsion. The synthesized PIL nanoparticles with a diameter of about 200 nm were fully characterized with regard to their chemical structures, morphologies, and properties using different techniques, such as Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy. To gain an in-depth understanding of the physical and morphological structures of the PIL nanoparticles in an emulsion, small-angle neutron scattering and ultra-small-angle neutron scattering were used. Neutron scattering studies revealed valuable information regarding the formation of cylindrical ionic micelles in the spherical nanoparticles, which is a unique property of this system. Furthermore, the PIL nanoparticle emulsion was utilized as an inhibitor in a self-assembled nanophase particle (SNAP) coating. The corrosion protection ability of the resultant coating was examined using potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that the PIL nanoparticle emulsion in the SNAP coating acts as an inhibitor of corrosion and is promising for fabricating advanced coatings with improved barrier function and corrosion protection.
Project description:Ionic liquids have significantly enhanced ecofriendly benefits compared to the traditional inhibitors. In the present work, new four polymeric ionic liquids based on benzoimidazole derivatives were synthesized through the reaction of 2-styryl-1H-benzo[d]imidazole with alkyl halide to form PIL1. Then, Cl- anions were exchanged with different anions through the neutralization reaction to form other investigated polymers. Their structures were chemically elucidated using Fourier transform infrared spectroscopy, 1H NMR, and 13C NMR. Their influence on carbon steel (CS) as corrosion inhibitors has been checked with dielectric spectroscopy in addition to potentiodynamic polarization curves. It was found that the percentage of inhibition efficiency increases as inhibitor's concentrations increase, suggesting a decrease in the rate of CS corrosion. Additionally, the hydrogen evolution rate controlled by the four polymers was monitored. Addition of the prepared polymers lessened the rate of generation of hydrogen as the inhibitor's concentrations augmented. Scanning electric electron microscopy in addition to energy-dispersive X-ray diffraction has proved the morphology of the CS surface as well as the formed protective film.
Project description:Polymeric micelles based on amphiphilic polysaccharides have some advantages as a carrier of poorly soluble lipophilic drugs thanks to their characteristic "core-shell" structure. Previously, ionic polymeric micelles based on chitosan and fatty acids have been developed. The aim of the present study was the preparation and characterization of hyaluronic acid (HA) derivatives by direct ionic interaction between the HA carboxylic groups and the amine groups of dodecyl amine (DDA) and hexadecyl amine (HDA). The HA-HDA polymeric micelles were loaded with a poorly soluble hydrophobic antifungal drug, clotrimazole (CLO). A 23 full factorial experimental design was used to evaluate the effect of the following factors: HA/HDA ratio from 1:0.25 to 1:0.75, cholesterol (CHOL%) as percentage of HA from 10% to 30%, and preparation temperature from 20 to 40 °C. As dependent variables (responses), nanoparticle dimensions and clotrimazole concentration in the final colloidal dispersion were considered. To optimize the drug final concentration, the design was therefore expanded into a rotatable central composite design (CCD). The effects of the formulation variables and the composition of the optimized formulation were confirmed by a mixture design. Physicochemical characterization of the optimized formulation was performed, confirming the ionic interaction between the polysaccharide and the HDA.
Project description:A corrosion inhibition mechanism of API 5L X60 steel exposed to 1.0 M H2SO4 was proposed from the evaluation of three vinylalkylimidazolium poly(ionic liquids) (PILs), employing electrochemical and surface analysis techniques. The synthesized PILs were classified as mixed-type inhibitors whose surface adsorption was promoted mainly by bromide and imidazolate ions, which along with vinylimidazolium cations exerted a resistive effect driven by a charge transfer process by means of a protective PIL film with maximal efficiency of 85% at 175 ppm; the steel surface displayed less surface damage due to the formation of metal-PIL complex compounds.
Project description:In the past, lives and wealth have been lost due to corrosion in almost all engineering fields. Not only this, the cost of reviving damaged equipments in the industry due to corrosion contributed a lot to the gross domestic product of a nation. Thus, all hands must be on desk to combat this harzadous act via time to time research on its final resolution. However, current research works have revealed effective and reliable corrosion inhibitors from pharmaceutical drugs, plant extracts and ionic liquids as organic green corrosion inhibitors (OGCIs) with accommodative attributes such as being environmentally friendly, readily available, biodegradable, non-harmful, relatively cheap and many others to mention a few. This paper opens readers mind into the detailed classifications, mechanisms and active functional groups of these eco-friendly OGCIs. Not only the corrosion efficiency calculation ways but also influencing factors on efficiency were presented. Plant extracts, pharmaceutical drugs, ionic liquids and synthetic inhibitors, as among major sources of OGCIs, used in preventing material corrosion in corrosive media were separately and comprehensively examined. The significance of values obtained from simulating presented mathematical models governing OGCIs kinetics, adsorption isotherm and adsorption thermodynamics was also included. In conclusion, beneficial recommendations for both current and prospective researchers in the field of Corrosion Engineering were presented.
Project description:The corrosion performance of carbon steel was tested in four polymeric ionic liquids (PILs) that differed only in the fatty acid linked to the chitosan (CS) amine group. The measurements were implemented involved the hydrogen evolution rate (HER), gravimetric measurements, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and quantum chemical estimations. The morphology and the elements arranged on the metal were considered by a scanning electron microscopy (SEM) system attached to an energy dispersive X-ray (EDX) system. The addition of polymeric ionic liquids hindered the rate of hydrogen generation. The order of the inhibitors efficiency was CSPTA-lauric > CSPTA-myristic > CSPTA-palmitic > CSPTA-stearic. The polarization method proved that the percentage inhibition efficiency increases with increasing the inhibitors concentration in 1 M HCl, representing a drop in the corrosion rate of carbon steel. On the other hand, the percentage inhibition decreased with the increase in temperature. Quantum chemical calculations revealed that the tested ionic liquids could react with the iron surface via electron transfer from the metal atom to ionic liquid molecule.
Project description:A biocompatible and antifouling polymeric medical coating was developed through rational design for anchoring pendant groups for the modification of stainless steel. Zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) was copolymerized individually with three anchoring monomers of carboxyl acrylamides with different alkyl spacers, including acryloylglycine (2-AE), 6-acrylamidohexanoic acid (6-AH), and 11-acrylamidoundecanoic acid (11-AU). The carboxylic acid groups are responsible for the stable grafting of copolymers onto stainless steel via a coordinative interaction with metal oxides. Due to hydrophobic interaction and hydrogen bonding, the anchoring monomers enable the formation of self-assembling structures in solution and at a metallic interface, which can play an important role in the thin film formation and functionality of the coatings. Therefore, surface characterizations of anchoring monomers on stainless steel were conducted to analyze the packing density and strength of the intermolecular hydrogen bonds. The corresponding copolymers were synthesized, and their aggregate structures were assessed, showing micelle aggregation for copolymers with higher hydrophobic compositions. The synergistic effects of inter/intramolecular interactions and hydrophobicity of the anchoring monomers result in the diversity of the thickness, surface coverage, wettability, and friction of the polymeric coatings on stainless steel. More importantly, the antifouling properties of the coatings against bacteria and proteins were strongly correlated to thin film formation. Ultimately, the key lies in deciphering the molecular structure of the anchoring pendants in thin film formation and assessing the effectiveness of the coatings, which led to the development of medical coatings through the graft-onto approach.
Project description:New ionic liquids with multiple Brönsted acid sites were synthesized in ?98% yield, and their inhibiting properties for the corrosion of carbon steel in 0.5?M HCl solution had been evaluated using electrochemical impedance spectroscopy, potentiodynamic polarization and weight loss method, finally the possible inhibiting mechanism was proposed according to UV-visible spectroscopic measurements and surface analysis including SEM and XPS techniques. The designed cation structure of Brönsted acid ionic liquids (BAILs), with one phenyl and two imidazolium rings, makes them good mixed-type inhibitors via the adsorption of BAILs on the steel surface to suppress both anodic and cathodic processes, obeying Langmuir adsorption isotherm. As potential acid catalysts, BAILs show nice corrosion inhibiting performance in acidic medium regardless of their Brönsted acidity, which is of great significance to enlarge the industry applications of BAILs.
Project description:Corrosion is clearly one of the more common causes of materials failure in stainless steel. To manage corrosion, chemical inhibitors are often used for prevention and control. Ionic liquids due to their hydrophobic and corrosion-resistant property are being explored as alternative protective coatings and anti-corrosion materials. In this particular study, ionic liquids containing functionalized imidazolium cations and tris(pentafluoroethyl)trifluorophosphate (FAP) anions were investigated for their ability to inhibit corrosion on stainless steel surfaces in acidic environment. Using surface characterization techniques, specifically scanning electron microscopy and energy-dispersive X-ray (EDX), the morphology and the elemental composition of the steel surfaces before and after corrosion were determined. Contact angle measurements were also performed to determine how these ionic liquids were able to wet the stainless steel surface. In addition, potentiodynamic studies were carried out to ensure that corrosion inhibition has occurred. Results show that these ionic liquids were able to inhibit corrosion on the stainless steel surfaces. This indicates promise in the use of these FAP-based ionic liquids for corrosion management in stainless steel.