Amine-capped Aniline Trimer Research Articles

Green and Heavy-Duty Anticorrosion Coatings: Waterborne Epoxy Thermoset Composites Modified through Variation of Zinc Dust Loading and Incorporation of Amine-Capped Aniline Trimer and Graphene Oxide.

In this study, an array of environmentally friendly and heavy-duty anticorrosion composite coatings were prepared. The synthesis involved amine-capped aniline trimer (ACAT) produced by an oxidative coupling reaction and graphene oxide (GO) prepared based on Hummer's method, and later, the waterborne epoxy thermoset composite (WETC) coatings were prepared by thermal ring-opening polymerization of EP 147w, a commercial waterborne epoxy resin, in the presence of ACAT and/or GO with zinc dust (ZD). A synergistic effect was observed by replacing a significant amount of the ZD loading in the WETC by simultaneously incorporating a small amount of ACAT and GO. The electrochemical corrosion measurements of the as-prepared WETC coatings indicated that incorporating 5% w/w ACAT or 0.5% w/w GO separately replaced approximately 30% w/w or 15% w/w of the ZD, respectively. Moreover, the WETC coatings containing 5% w/w ACAT and 0.5% w/w GO simultaneously were found to replace 45% w/w of the ZD. A salt spray test based on ASTM B-117 also showed a consistent trend with the electrochemical results. Incorporating small amounts of ACAT and GO in WETC coatings instead of ZD not only maintains the anticorrosion performance but also enhances adhesion and abrasion resistance, as demonstrated by the adhesion and abrasion tests.

Valorization of Agricultural Waste as a Chemiresistor H2S-Gas Sensor: A Composite of Biodegradable-Electroactive Polyurethane-Urea and Activated-Carbon Composite Derived from Coconut-Shell Waste.

In this study, a high-performance H2S sensor that operates at RT was successfully fabricated using biodegradable electroactive polymer-polyurethane-urea (PUU) and PUU-activated-carbon (AC) composites as sensitive material. The PUU was synthesized through the copolymerization of biodegradable polycaprolactone diol and an electroactive amine-capped aniline trimer. AC, with a large surface area of 1620 m2/g and a pore diameter of 2 nm, was derived from coconut-shell waste. The composites, labeled PUU-AC1 and PUU-AC3, were prepared using a physical mixing method. The H2S-gas-sensing performance of PUU-AC0, PUU-AC1, and PUU-AC3 was evaluated. It was found that the PUU sensor demonstrated good H2S-sensing performance, with a sensitivity of 0.1269 ppm-1 H2S. The H2S-gas-sensing results indicated that the PUU-AC composites showed a higher response, compared with PUU-AC0. The enhanced H2S-response of the PUU-AC composites was speculated to be due to the high surface-area and abounding reaction-sites, which accelerated gas diffusion and adsorption and electron transfer. When detecting trace levels of H2S gas at 20 ppm, the sensitivity of the sensors based on PUU-AC1 and PUU-AC3 increased significantly. An observed 1.66 and 2.42 times' enhancement, respectively, in the sensors' sensitivity was evident, compared with PUU-AC0 alone. Moreover, the as-prepared sensors exhibited significantly high selectivity toward H2S, with minimal to almost negligible responses toward other gases, such as SO2, NO2, NH3, CO, and CO2.

Comparative Studies on Carbon Paste Electrode Modified with Electroactive Polyamic Acid and Corresponding Polyimide without/with Attached Sulfonated Group for Electrochemical Sensing of Ascorbic Acid.

In this study, electroactive poly (amic acid) (EPAA) and corresponding polyimide (EPI) without or with a sulfonated group (i.e., S-EPAA, and S-EPI) were prepared and applied in electrochemical sensing of ascorbic acid (AA). The electroactive polymers (EAPs) containing EPAA/EPI and S-EPAA/S-EPI were synthesized by using an amine-capped aniline trimer (ACAT) and sulfonated amine-capped aniline trimer (S-ACAT) as an electroactive segment that controlled the redox capability and influenced the degree of sensitivity of the EAPs towards AA. Characterization of the as-prepared EAPs was identified by FTIR spectra. The redox capability of the EAPs was investigated by electrochemical cyclic voltammetric studies. It should be noted that the redox capability of the EAPs was found to show the following trend: S-EPAA > S-EPI > EPAA > EPI. For the electrochemical sensing studies, a sensor constructed from an S-EPAA-modified carbon paste electrode (CPE) demonstrated 2-fold, 1.27-fold, and 1.35-fold higher electro-catalytic activity towards the oxidation of AA, compared to those constructed using a bare CPE, S-EPI-, and EPI/EPAA-modified CPE, respectively. The higher redox capability of S-EPAA-modified CPE exhibited a good electrochemical response towards AA at a low oxidative potential, with good stability and selectivity. Moreover, an electrochemical sensor constructed from S-EPAA-modified CPE was found to reveal better selectivity for a tertiary mixture of AA/DA/UA, as compared to that of EPI-modified, EPAA-modified and S-EPI-modified CPE, based on a series of differential pulse voltammograms.

UV-cured electroactive polyurethane acrylate coatings with superhydrophobic surface structure of biomimetic peacock feather for anticorrosion application

In this work, UV-cured electroactive polyurethane acrylate (EPU) materials with the superhydrophobic surface structure of biomimetic peacock feather were firstly prepared and applied in anticorrosive coatings. Firstly, amine-capped aniline trimer (ACAT) and vinyl-capped aniline trimer (VCAT) were synthesised and characterised by 1H-nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy. Polyurethane acrylate (PUA) was synthesised and characterised by 1H NMR and FTIR spectroscopy. EPU was then prepared through the UV curing of PUA with 0, 1, 3 and 5 wt% VCAT (named EPU0, EPU1, EPU3 and EPU5, respectively) and characterised via FTIR. The redox capabilities of the as-prepared EPU series were investigated by cyclic voltammetry studies. EPU with higher VCAT loading (EPU5) exhibited better corrosion protection performance than those with lower VCAT loadings (EPU0, EPU1 and EPU3) based on a series of electrochemical corrosion measurements because of the formation of a dense metal oxide layer as evidenced by Raman spectroscopy. Moreover, EPU5 with the surface structure of biomimetic peacock feather (denoted by BEPU5) was prepared by nanocasting technique with polydimethylsiloxane as the flexible transparent negative template. The surface morphology and wettability of BEPU5 was investigated by scanning electron microscopy and contact angle (CA) analysis. The CA of BEPU5 remarkably increased to 145° compared with that of EPU5 63°. This massive increase in CA indicates efficient superhydrophobic properties, which were induced by the biomimetic peacock feather and produced outstanding corrosion protection performance for short and long terms based on a series of electrochemical corrosion measurements. This study is the first of its type to produce a biomimetic feather with massive increase in superhydrophobic properties, which is expected to revolutionise biomimetic industrial coating technologies towards better corrosion protective coatings.

Corrosion Resistance of Mild Steel Coated with Phthalimide-Functionalized Polybenzoxazines

Herein, we synthesized two new phthalimide-functionalized benzoxazine monomers, pPP-BZ and oPP-BZ, through Mannich reactions of 2-(4-hydroxyphenyl)isoindoline-1,3-dione (pPP) and 2-(2-hydroxyphenyl)isoindoline-1,3-dione (oPP), respectively, with p-toluidine and paraformaldehyde. The structures of these two monomers were confirmed using Fourier transform infrared (FTIR) and nuclear magnetic resonance spectroscopy. We used differential scanning calorimetry, FTIR spectroscopy, and thermogravimetric analysis to study the polymerization behavior and thermal stability of the monomers and their corresponding polybenzoxazines. Poly(pPP-BZ) and poly(oPP-BZ) were formed on mild steel (MS) through spin-coating and subsequent thermal curing polymerization. We used various corrosion testing methods to examine the effect of the curing temperature on the corrosion resistance of the coated MS samples in 3.5 wt.% aqueous solution of NaCl. Among our tested systems, the corrosion rate reached a low of 2.78 µm·Y−1 for the MS coated with poly(pPP-BZ)180 (i.e., the coating that had been cured at 180 °C); this value is much lower than that (4.8 µm·Y−1) reported for a maleimide-based benzoxazine compound (MI-Bz)/33 wt.% ACAT (amine-capped aniline trimer) blend. Thus, the incorporation of the imide functional group into the PBZ coatings is an effective strategy for affording high-performance corrosion resistance.

A Novel Application of Electroactive Polyimide Doped with Gold Nanoparticles: As a Chemiresistor Sensor for Hydrogen Sulfide Gas.

This research paper presents a new application of electroactive polyimide doped with gold nanoparticles (PI/AuNPs) as a chemiresistor sensor for detecting hydrogen sulfide gas. The synthesis of PI/AuNPs was done in a simple 3-step process of polymerization using the as prepared amine-capped aniline trimer (ACAT), followed by imidization, and doping. Spectral analyses via FTIR, LC-MS and 1H-NMR confirmed the formation of amine-capped aniline trimer with a MW of 288 g mol−1. Comparison of ACAT, BSAA, and PI FTIR spectra showed successful polymerization of the last, while XRD validated the incorporation of metal nanoparticles onto the polymer matrix, showing characteristic diffraction peaks corresponding to gold. Furthermore, TEM, and FE-SEM revealed the presence of well-dispersed Au nanoparticles with an average diameter of about 60 nm. The electroactive PI/AuNPs-based sensor showed a sensitivity of 0.29% ppm−1 H2S at a linear concentration range of 50 to 300 ppm H2S (r = 0.9777). The theoretical limit of detection was found at 0.142 ppm or 142 ppb H2S gas. The sensor provided a stable response reading at an average response time of 43 ± 5 s, which was easily recovered after an average time of 99 ± 5 s. The sensor response was highly repeatable and reversible, with RSD values of 8.88%, and 8.60%, respectively. Compared with the performance of the conventional conducting polyaniline also doped with gold nanoparticles (PANI/AuNPs), the fabricated electroactive PI/AuNPs exhibited improved sensing performance making it a potential candidate in monitoring H2S in the environment and for work-related safety.

Effective anticorrosion coatings prepared from sulfonated electroactive polyurea

In the present study, the sulfonated electroactive polyurea (S-EPU) was first prepared and characterized, applied as an anticorrosion coating. The electroactive oligomer sulfonated amine-capped aniline trimer (S-ACAT) was synthesized by oxidative coupling reaction, followed by characterization using Fourier-transform infrared (FTIR) and mass spectroscopy (MS). For the preparation of sulfonated electroactive polyurea (S-EPU), isophorone diisocyanate (IPDI) was reacted with poly(tetramethylene ether) glycol (PTMEG) in the presence of a specific amount of diamine S-ACAT. The success of the S-EPU was confirmed through FTIR and GPC. After that the redox capability of as-prepared S-EPU was confirmed by CV studies. Chemical oxidization of S-EPU, carried out through the introduction of trace amount of ammonium persulfate, was monitored by UV-VIS spectroscopy. The electrochemical corrosion of the electroactive polymer-coated cold-rolled steel (CRS) electrode, in neutral, acidic and alkaline conditions, were measured and compared. As compared to non-electroactive polyurea (N-EPU), results showed enhanced corrosion protection of the S-EPU coating and electroactive polyurea (EPU) coating, owing to their redox capability that induces the formation of densely passive metal oxide layer (e.g., Fe2O3 and Fe3O4). The densely metal oxide layers induced by S-EPU/EPU coatings were further confirmed by Raman spectroscopy, SEM and ESCA. Moreover, the S-EPU coating exhibited better anticorrosion performance than that of EPU coating which could be attributed to the higher electro-catalytic property of S-EPU coating upon CRS electrode, causing the formation of more densely metal oxide layers to shelter the underlying metal substrate.

Water Soluble Trianiline Containing Polyurethane (TAPU) as an Efficient Corrosion Inhibitor for Mild Steel

Novel trianiline containing water soluble polyurethane (TAPU) was synthesized by polymerization of polyethylene glycol, toluene diisocyanate and amine-capped aniline trimer. The influence of TAPU on the corrosion inhibition of mild steel in 1 M HCl was investigated using weight loss measurements, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS). The performance of TAPU on the corrosion inhibition of mild steel was also evidenced by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and atomic force microscope (AFM). Results confirmed that the adsorption of TAPU on the mild steel surface and consequent inhibition of the corrosion process. The inhibition efficiency (IE%) increased with a rise in TAPU concentration, reaching a value up to 97% at a concentration of 200 mg/l. Potentiodynamic polarization curves showed that the TAPU affected both cathodic and anodic protection and was a mixed type inhibitor in HCl corrosive medium. Adsorption isotherm studies confirmed that the adsorption of TAPU on the mild steel surface in 1 M HCl solution obeyed Langmuir adsorption isotherm. EDS analysis determined the adsorption of TAPU molecules on the steel surface, and the absorbed TAPU provided an effective corrosion inhibition in 1 M HCl solution from observation of surface morphology by SEM and AFM.

Oligoanilines as a suppressor of polysulfide shuttling in lithium–sulfur batteries

Amine-capped aniline trimer (ACAT) with a strong interaction with polysulfides (LiPS) facilitates the formation of bulky ACAT–LiPS complexes, which are then size-selectively sieved and stabilized within the cathode in lithium–sulfur batteries.

Non-covalent functionalized hexagonal boron nitride nanoplatelets to improve corrosion and wear resistance of epoxy coatings

In the present study, a non-covalent method was employed to modify hexagonal boron nitride (h-BN) nanoplateletsviaπ–π interaction of amine-capped aniline trimer (AT), which resulted in a stable dispersion of h-BN nanoplatelets in organic solvents.

Enhancement of mechanical and wear resistance performance in hexagonal boron nitride-reinforced epoxy nanocomposites

Hexagonal boron nitride (hBN), a two-dimensional nanofiller with good mechanical properties, high thermal conductivity and excellent lubrication properties, has the potential to substantially reinforce polymers to form nanocomposites with advanced properties. In this study, we successfully prepared hBN nanosheets with a thickness of a few atoms by using amine-capped aniline trimer (AT) as dispersant. Epoxy/hBN nanocomposites were prepared by curing reaction of epoxy E51, Jeffamine D230 and AT-modified hBN nanosheets, where the hBN contents were 0.5, 1, 2 and 4 wt%. An increase in contact angle of the epoxy/hBN nanocomposites was evident in the presence of hBN nanosheets, implying an increase in the hydrophobic nature of the composites. The as-prepared composites exhibited enhanced mechanical and tribological performance compared to pure epoxy resin. This effectiveness in improving the mechanical, friction and wear behavior of the epoxy composites could be attributed to the complementary action of excellent mechanical properties, lubrication and thermal conductivity of hBN nanofillers. (c) 2016 Society of Chemical Industry

Biocompatible, Biodegradable, and Electroactive Polyurethane-Urea Elastomers with Tunable Hydrophilicity for Skeletal Muscle Tissue Engineering

It remains a challenge to develop electroactive and elastic biomaterials to mimic the elasticity of soft tissue and to regulate the cell behavior during tissue regeneration. We designed and synthesized a series of novel electroactive and biodegradable polyurethane-urea (PUU) copolymers with elastomeric property by combining the properties of polyurethanes and conducting polymers. The electroactive PUU copolymers were synthesized from amine capped aniline trimer (ACAT), dimethylol propionic acid (DMPA), polylactide, and hexamethylene diisocyanate. The electroactivity of the PUU copolymers were studied by UV-vis spectroscopy and cyclic voltammetry. Elasticity and Young's modulus were tailored by the polylactide segment length and ACAT content. Hydrophilicity of the copolymer films was tuned by changing DMPA content and doping of the copolymer. Cytotoxicity of the PUU copolymers was evaluated by mouse C2C12 myoblast cells. The myogenic differentiation of C2C12 myoblasts on copolymer films was also studied by analyzing the morphology of myotubes and relative gene expression during myogenic differentiation. The chemical structure, thermal properties, surface morphology, and processability of the PUU copolymers were characterized by NMR, FT-IR, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and solubility testing, respectively. Those biodegradable electroactive elastic PUU copolymers are promising materials for repair of soft tissues such as skeletal muscle, cardiac muscle, and nerve.

Reaction mechanism and synergistic anticorrosion property of reactive blends of maleimide-containing benzoxazine and amine-capped aniline trimer

Reaction mechanism and synergistic effect on anticorrosion for reactive blends of a maleimide-containing benzoxazine and aniline trimer have been explored.

Synergistic effect of electroactivity and hydrophobicity on the anticorrosion property of room-temperature-cured epoxy coatings with multi-scale structures mimicking the surface of Xanthosoma sagittifolium leaf

A novel method is introduced to fabricate an electroactive epoxy (EE) coating with structured hydrophobic surfaces using an environmentally friendly process for anticorrosion application. First of all, the electroactive amine-capped aniline trimer (ACAT) was used as a curing agent to cure the epoxy resin and additionally provided electroactivity to the cured epoxy resin. The EE coating was cured at room temperature without using any solvent. The increased amount of the ACAT component in the EE coating not only accelerated the curing process but also promoted the thermal stability and anticorrosion performance. Subsequently, the multi-scale papilla-like structures on the surface of the Xanthosoma sagittifolium leaf were successfully replicated on the surface of the EE coating using PDMS as a negative template, as evidenced by the SEM investigation. The resulting hydrophobic electroactive epoxy (HEE) coating with the replicated nanostructured surface showed a hydrophobic characteristic with a water contact angle close to 120°. The developed HEE coating exhibited superior anticorrosion performance in electrochemical corrosion tests as its corrosion rate is better than that of the bare steel substrate by a factor of 450. The significantly improved corrosion protection is attributed to, besides the steel substrate isolated by the coating, the synergistic effect of electroactivity and hydrophobicity from the HEE coatings with the multi-scale structures mimicking the surface of the Xanthosoma sagittifolium leaf.

Electrochemical corrosion protection studies of aniline-capped aniline trimer-based electroactive polyurethane coatings

In this paper, the successful preparation of electroactive polyurethane (EPU) coatings containing amine-capped aniline trimer (ACAT) is presented for the first time. To accomplish this, ACAT was synthesized by carrying out oxidative coupling reactions between aniline and para-phenylenediamine, after which it was characterized through Fourier-transformation infrared and UV–vis spectroscopy. Subsequently, a polyurethane (PU) prepolymer was prepared by polymerizing diisocyanate of 4,4-methylene-bis(cyclohexylisocyanate), diol of polycaprolactone, and triol of phloroglucinol at 60 °C for 3 h. EPU was then produced by allowing the as-prepared polyurethane prepolymer to react with ACAT under suitable conditions. Non-electroactive polyurethane (NEPU) coating was also prepared for the control experiments. Based on a series of electrochemical corrosion measurements, EPU in the form of a coating was found to possess a clearly enhanced corrosion protection effect when compared to PU. The observed enhancement of the anticorrosion effect of EPU on a metallic substrate when compared to that of NEPU may have been caused by the redox catalytic capability of ACAT present in EPU, inducing the formation of a densely passive metal oxide layer ( i.e., Fe 2O 3 and Fe 3O 4), as indicated by the results of scanning electron microscopy and electron spectroscopy for chemical analysis. The redox behavior of the EPU coatings was further analyzed and compared to that of the NEPU coating by cyclic voltammetric (CV) studies.

Mechanically and Thermally Enhanced Intrinsically Dopable Polyimide Membrane with Advanced Gas Separation Capabilities

In this paper, we present the first preparation of an intrinsically dopable polyimide (DPI) membrane containing an amine-capped aniline trimer (ACAT) that reveals advanced gas separation capabilities as well as mechanically and thermally enhanced properties. The as-prepared DPI membrane was synthesized by reacting ACAT and 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (BSAA) through a conventional thermal imidization reaction. Polyaniline (PANI) and conventional nondopable polyimide (NDPI) membranes were also prepared as controls. The DPI membranes were found to reveal permselectivities (α) of O2/N2 of about 13.54, which is about 1.96- and 1.54-fold higher than that of NDPI and PANI, respectively, based on the investigation of gas permeability analysis (GPA). Upon doping with 1.0 M HCl (aq), the pemselectivities of DPI for O2/N2 were found to be further increased to about 16.63. Moreover, significantly enhanced mechanical and thermal properties of the as-prepared DPI membrane were also found ...

Electrochemical studies for the electroactivity of amine-capped aniline trimer on the anticorrosion effect of as-prepared polyimide coatings

The electroactive polyimide consisting of various content of amine-capped aniline trimers (ATs) have been successfully synthesized and characterized by Fourier-Transformation infrared and UV–visible absorption spectroscopy. The electroactivity of as-prepared polyimides was tested by electrochemical cyclic voltammetry (CV) studies. It was noticed that the as-prepared electroactive polyimide with higher content of amine-capped ATs shows higher electroactivity (i.e., larger redox current) than that of non-electroactive polyimide, leading to enhance corrosion protection efficiency on cold-rolled steel (CRS) electrodes. This enhanced corrosion protection efficiency has been explained based on a series of electrochemical measurements such as corrosion potential, polarization resistance, corrosion current and electrochemical impedance spectroscopy (EIS) studies in 5 wt-% NaCl electrolyte. This significant enhancement of corrosion protection on CRS electrodes as compared to non-electroactive polyimide might probably be attributed to the redox catalytic property of as-prepared electroactive polyimide coatings inducing the formation of passive layer of metal oxide.

Oligoaniline-Contained Electroactive Silsesquioxane Precursor for Synthesizing Novel Siliceous Materials

As analogues of the well-known conducting polymer polyaniline, aniline oligomers have been extensively investigated because of their well-defined structure, good solubility, and electroactivity. In this study, we demonstrated for the first time the successful and high-yield synthesis of a novel electroactive organo-bridged silsesquioxane precursor, N,N‘-bis(4‘-(3-triethoxysilylpropyl-ureido)phenyl)-1,4-quinonenediimine (TSUPQD), which covalently incorporates the emeraldine form of amine-capped aniline trimer into silica frameworks via one-step coupling reaction with triethoxysilylpropyl isocyanate (TESPIC) under a mild condition. Subsequently, detailed characteristics of the resulting silsesquioxane compound along with morphological measurement were systematically studied by using spectroscopic methods, such as Fourier-transform infrared (FTIR) spectra, mass spectra (MS), nuclear magnetic resonance (NMR) spectroscopy, and X-ray powder diffraction (XRD). In addition, its electrochemical behavior was explored by UV−vis spectra and cyclic voltammetry showing that its intrinsic electroactivity was maintained upon protonic acid doping and presented two distinct oxidative states in reversible cyclic voltammetry, similar to that of polyaniline. Furthermore, the sol−gel reactions of TSUPQD with various amounts of tetraethyl orthosilicate (TEOS) were carried out to afford new electroactive hybrid siliceous materials whose properties were also studied.