Electrochemical investigations of the anticorrosive and electrochromic properties of electroactive polyamide

Modeling Experimental Parameters for the Fabrication of Multifunctional Surfaces Composed of Electrospun PCL/ZnO-NPs Nanofibers

In this work, a one-step electrospinning technique has been implemented for the design and development of functional surfaces with a desired morphology in terms of wettability and corrosion resistance by using polycaprolactone (PCL) and zinc oxide nanoparticles (ZnO NPs). The surface morphology has been characterized by confocal microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM) and water contact angle (WCA), whereas the corrosion resistance has been evaluated by Tafel polarization curves. Strict control over the input operational parameters (applied voltage, feeding rate, distance tip to collector), PCL solution concentration and amount of ZnO NPs have been analyzed in depth by showing their key role in the final surface properties. With this goal in mind, a design of experiment (DoE) has been performed in order to evaluate the optimal coating morphology in terms of fiber diameter, surface roughness (Ra), water contact angle (WCA) and corrosion rate. It has been demonstrated that the solution concentration has a significant effect on the resultant electrospun structure obtained on the collector with the formation of beaded fibers with a higher WCA value in comparison with uniform bead-free fibers (dry polymer deposition or fiber-merging aspect). In addition, the presence of ZnO NPs distributed within the electrospun fibers also plays a key role in corrosion resistance, although it also leads to a decrease in the WCA. Finally, this is the first time that an exhaustive analysis by using DoE has been evaluated for PCL/ZnO electrospun fibers with the aim to optimize the surface morphology with the better performance in terms of corrosion resistance and wettability.

A novel Au/electroactive poly(amic acid) composite as an effective catalyst for p-nitrophenol reduction

A Au/electroactive poly(amic acid) (Au/EPAA) composite was synthesized and characterized, and its catalytic ability was evaluated. EPAA was synthesized via oxidative coupling polymerization and Au nanoparticles were anchored to the amino and carboxyl groups. The Au/EPAA composite was characterized via X-ray diffraction analysis, X-ray photoelectron spectroscopy, and scanning electron microscopy, which confirmed that the Au nanoparticles were well dispersed on the EPAA surface. p-Nitrophenol was reduced to p-aminophenol within 5 min at room temperature, with a rate constant of 0.84 min⁻¹. Cycling measurements showed that the Au/EPAA composite achieved higher than 92% conversion. The Au/EPAA composite showed excellent performance and stability as a catalyst for the reduction of p-nitrophenol to p-aminophenol.

The Au/EPAA composite demonstrated excellent performance and stability as a catalyst for the reduction of p-nitrophenol to p-aminophenol.

A Novel Electroactive Imide Oligomer and Its Application in Anticorrosion Coating

A novel aniline tetramer (AT) capped electroactive imide oligomer (EIO) for metal corrosion protection was successfully synthesized in this study. The chemical structure of the EIO was characterized by liquid chromatography-mass spectrometry and Fourier-transform infrared spectroscopy. Furthermore, the redox behavior of EIO was identified using electrochemical cyclic voltammetry studies. An EIO coated on a cold-rolled steel (CRS) electrode was found to possess superior corrosion resistance to polyimide (PI) on a series of electrochemical corrosion measurements in 3.5 wt.% NaCl solution over an extended period (30 days). The mechanism for the advanced corrosion protection of the PI coating on the CRS electrode could be attributed to the redox catalytic capabilities of the AT units present in the EIO. These capabilities may induce the formation of passive metal oxide layers on the CRS electrode. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to analyze the surface condition of the CRS after the corrosion test. EIO- and PI-coated electrodes were identified by a series of electrochemical measurements, including corrosion potential (E_corr), polarization resistance (R_p), and corrosion current (I_corr) measurements, along with electrochemical impedance spectroscopy (EIS).

Protection of Mild Steel by Waterborne Epoxy Coatings Incorporation of Polypyrrole Nanowires/Graphene Nanocomposites

Polypyrrole nanowires/graphene (PPyNG) nanocomposites as anticorrosive fillers were prepared by in situ polymerization in order to improve the anticorrosion performance of waterborne epoxy coatings. Field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR) characterized the morphologies and structures of the synthesized PPyNG. The polypyrrole nanowires with about 50 nm in diameter were obtained. Conjugation length of PPy was increased with the addition of graphene. Open circuit potential (OCP) measurements, Tafel polarization curves, and electrochemical impedance spectroscopy (EIS) using an electrochemical workstation evaluated the anticorrosion properties of the waterborne epoxy/PPyNG coatings (EPPyNG). The studied nanocomposite coating possessed superior corrosion protection performance when the graphene content of the filler was 2 wt %. Its corrosion rate was about 100 times lower than that of neat epoxy coating. The higher barrier properties of nanocomposite coating and passivation effect of polypyrrole nanowires were beneficial in corrosion protection.

Effect of Silane on the Active Aging Resistance and Anticorrosive Behaviors of Natural Lacquer

Environmentally friendly and renewable hybrid lacquer coatings with excellent aging resistant and anticorrosion properties were studied. The coatings were prepared using raw lacquer coupled with the silane agent 3-aminopropyltriethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane via an eco-friendly sol-gel preparation process. The physical-mechanical properties, thermal stability, aging resistance, and anticorrosion properties of the as-prepared coatings were analyzed. Additionally, the surface of the coatings before and after an accelerated aging treatment was studied by scanning electron microscopy and X-ray photoelectron spectroscopy. The results revealed that the hybrid lacquer coating A (with a raw lacquer-to-APTES mass ratio of 1.8:1) resulted in films with a significantly enhanced antiaging effect (e.g., six times higher than that of lacquer at a gloss loss rate of 30%). Besides, this film revealed an exceptional anticorrosion performance (with the lowest corrosion current I _corr = 2.476 × 10^-10 A·cm^-2) and a high protection efficiency (99.99 and 94.10%), as demonstrated by its electrochemical characteristics. Furthermore, all films exhibited a good barrier because of their dense structure, which prevents the corrosive medium from penetrating the coating during the salt spray test analysis after 1000 h. And the coating A relatively layered was distributing any significant cancaves, integrity better than all coatings studied, indicating that the based electrolyte was easier to penetrate it after salt spraying 2000 h.

Synergistic Effect of Polypyrrole-Intercalated Graphene for Enhanced Corrosion Protection of Aqueous Coating in 3.5% NaCl Solution

Dispersion of graphene in water and its incorporation into waterborne resin have been rarely researched and hardly achieved owing to its hydrophobicity. Furthermore, it has largely been reported that graphene with impermeability contributed to the improved anticorrosion property. Here, we show that highly concentrated graphene aqueous solution up to 5 mg/mL can be obtained by synthesizing hydrophilic polypyrrole (PPy) nanocolloids as intercalators and ultrasonic vibration. On the basis of π-π interaction between PPy and graphene, stacked graphene sheets are exfoliated to the thickness of three to five layers without increasing defects. The corrosion performance of coatings without and with PPy and graphene is obtained by potential and impedance measurements, Tafel curves, and fitted pore resistance by immersing in a 3.5 wt % NaCl solution. It turns out that composite coating with 0.5 wt % graphene additive exhibits superior anticorrosive ability. The mechanism of intercalated graphene-based coating is interpreted as the synergistic protection of impermeable graphene sheets and self-healing PPy and proved by the identification of corrosion products and the scanning vibrating electrode technique.

Bio-inspired electrochemical corrosion coatings derived from graphene/natural lacquer composites

To develop green efficient anti-corrosion coatings, graphene/lacquer composite coatings were demonstrated.

Advanced anti-corrosion coatings prepared from α-zirconium phosphate/polyurethane nanocomposites

This paper presents the first successful application of α-zirconium phosphate/polyurethane (ZrP/PU) nanocomposites for corrosion protection.