Graphene(G)-based polymer nanocomposites have attracted great interest owing to their superior physicochemical properties over polymers. However, the tendency of graphene sheets to aggregate makes it ...difficult to achieve homogenous dispersion in polymer matrix. Herein, by utilization of poly(2-butylaniline) (P2BA) as a dispersing agent, stable dispersion of graphene in organic solvents was achieved via non-covalent π-π interactions between P2BA and graphene nanosheets. The exfoliated graphene nanosheets were then integrated with coating matrix by curing reaction of epoxy resin with P2BA functionalized graphene (P2BA-G) and amine hardener. Embedding a small percentage of well-dispersed graphene nanosheets (P2BA0.5%-G0.5%) in epoxy coating remarkably improved anticorrosion performance and wear resistance properties, which was attributed to the synergistic effects of the redox catalytic capability of P2BA, high mechanical and barrier properties of well-dispersed graphene nanosheets in the epoxy matrix. The present study provides a promise strategy for development of graphene reinforced organic coatings with superior physical-mechanical properties for metal protection.
Display omitted
In present study, novel nitrogen doped carbon dots (NCDs) are synthesized using a green material—dopamine—as a precursor and studied as corrosion inhibitors for Q235 carbon steel in 1 M HCl solution. ...According to the electrochemical results, it is found that NCDs acting as a mixed-type corrosion inhibitor can effectively retard the acid corrosion of carbon steel, and their inhibition efficiency increases with the concentration increasing from 50 to 400 ppm. The highest inhibition efficiency is 96.1% in the presence of 400 ppm NCDs at room temperature. Additionally, the adsorption of NCDs obeys the Langmuir adsorption isotherm. In addition, weight loss results show that the inhibition efficiency in the presence of 400 ppm NCDs increases with prolonged exposure time and rising temperature (298–328 K), owing to the strong adsorption of NCDs on the steel surface, and the η value is 92.2% at 60 h of immersion and 86.2%, 89.1%, 90.6% and 92.9% at 298, 308, 318 and 328 K, respectively. Surface analysis by scanning electron microscope (SEM), laser scanning confocal microscope (LSCM) and X-ray photoelectron spectroscopy (XPS) further proves the formation of a protective NCD film on the steel surface.
Polyurea (PU) materials are widely used in civil and military fields owing to their excellent weather, wear and corrosion resistance, impact resistance and energy absorption ability. In this study, ...polyurea nanocomposites integrated with polydopamine functionalized graphene oxide (GO@PDA) were reported. The functionalization of graphene oxide (GO) with polydopamine was achieved under mild conditions to optimize the dispersion and interfacial compatibility of GO within the PU matrix, thereby reinforcing the mechanical properties of PU materials. The quasi-static and dynamic compressive behaviors of PU nanocomposites under various strain rates (0.001–7000 s−1) were comprehensively investigated through a universal testing machine and split Hopkinson pressure bar (SHPB), respectively. Results revealed a significant enhancement in the strain-rate sensitivity, flow strength, yield strength, and strain energy density with the increasing strain rate and GO@PDA content. Particularly, at a strain rate of 7000 s−1, GO@PDA1.0%/PU nanocomposite exhibited a remarkable increase of 33% and 54% in flow strength and yield strength, respectively. This remarable enhancement was closely related with the effective dispersion and superior interfacial compatibility between GO@PDA and PU matrix. Eventually, to offer a comprehensive understanding of the mechanical behavior of PU nanocomposites, a visco-hyperelastic intrinsic model was employed to accurately capture the mechanical response under various strain rates.
In this study, to achieve a compatible and good dispersion of graphene in polyimide matrix, we synthesized an aromatic diamine, aniline trimer, as a polymerizable graphene dispersant. ...Polyimide/graphene nanocomposites with 0.25-2% mass fraction of graphene were prepared by
in situ
condensation of pyromellitic dianhydride, 4,4′-oxydianiline, and aniline trimer (AT) functionalized graphene in DMAc, following subsequent thermal imidization at elevated temperatures. UV-vis and Raman spectroscopy verified the π-π interactions between AT and graphene. The microstructure analysis using XRD, SEM, and TEM were performed to investigate the morphology of graphene in the polyimide matrix. The thermal, mechanical, and tribological properties of polyimide/graphene nanocomposites were investigated by TGA, DMA, and friction and wear tests. In view of the ease of preparation and their superior physical properties over neat polyimide, PI/G composites prepared in this study showed promising applications as wear-resistant and self-lubricating materials.
In this study, to achieve a compatible and good dispersion of graphene in polyimide matrix, we synthesized an aromatic diamine, aniline trimer, as a polymerizable graphene dispersant.
Novel nitrogen and sulfur co-doped carbon dots (N,S-CDs) were synthesized
via
a hydrothermal procedure using citric acid (CA) and thiourea (TU) as precursors, and the corresponding corrosion ...protection performance was first investigated for Q235 carbon steel in 1 M HCl solution. Experimental results indicated that N,S-CDs as mixed-type corrosion inhibitors could effectively prevent Q235 carbon steel from corrosion in 1 M HCl solution, and the corrosion inhibition efficiency was improved with the increase in N,S-CD concentration. The maximum value was achieved at 400 ppm of N,S-CDs at 25 °C, which was approximately 96.6%, 94.6% and 90.55%, according to the potentiodynamic polarization curves, EIS results and weight loss measurement, respectively. Additionally, with the temperature ranging from 25 to 55 °C, the inhibition efficiency obtained from the weight loss measurement was enhanced from 90.55% to 94.04%. Such superior inhibition effect was assigned to the physisorption and chemisorption of N,S-CDs on the Q235 carbon steel surface, which was also be confirmed by XPS analysis. The adsorption of N,S-CDs onto a steel substrate conformed to the Langmuir adsorption isotherm.
N,S-CDs as ecofriendly inhibitors effectively inhibit the acid corrosion of carbon steel with an inhibition efficiency of 96.6%.
•The modification of the GO with PDA improves the compatibility between GO and EP.•EIS results show that the GO-PDA/EP has longer service life than blank EP.•SVET results imply that GO-PDA/EP with ...damages has better corrosion resistance.
This study reports an eco-friendly water-borne epoxy (EP) with enhanced corrosion protection performance by embedding graphene oxide (GO). For this purpose, the dispersion of the GO in ethanol is improved by modifying the GO nanosheets with hydrophilic dopamine (DA), owing to the π-π interactions between the GO and self-polymerized polydopamine (PDA) as well as the covalent bonding between DA and GO. Results obtained from transmittance electron microscopy (TEM), scanning probe microscopy (SPM) Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, UV–vis absorbance spectroscopy and X-ray photoelectron spectroscopy (XPS) reveal the successful modification of PDA on the surface of GO nanosheets. Besides, the GO/EP and GO-PDA/EP coatings are applied on the steel substrates and their corrosion protection performance is investigated via electrochemical measurements, scanning electron microscopy (SEM) and scanning vibration electrochemical technology (SVET). Results demonstrate that inclusion of well-dispersed GO-PDA nanosheets leads to the remarkable improvement in the corrosion protection performance of water-borne EP coating.
Polyimide (PI)/graphene oxide (GO) nanocomposites with different loads of polydopamine-modified graphene oxide (PI/PDA-GO) were prepared. Meanwhile, the as-prepared PI/PDA-GO nanocomposites were ...compared with pure PI in terms of their morphologies, thermal and mechanical properties. Only a minor mass fraction of PDA-GO was required to enhance the mechanical and thermal properties of PI. The tensile strength of 1 wt% PDA-GO/PI was increased by 12% and the tensile modulus of 1 wt% PDA-GO/PI nanocomposites was increased by 25% compared to those of pure PI. Vickers hardness of the PI hybrid films increased with PDA-GO load and the maximum enhancement in Vickers hardness was observed at 2 wt% PDA-GO loading. On the other hand, the storage modulus of 1 wt% PDA-GO/PI was increased by 54% than that of neat PI. In consideration of the facile preparation of PDA-coated GO, superior physical properties over neat PI, PI/PDA-GO nanocomposites showed promising applications as functional films or composites.
Display omitted
Carbon steel is the most widely used engineering material, and its corrosion is one of the main areas of concern in many industries. The most practical approach to control this ...problem is to use corrosion inhibitors. Currently, because of their good water solubility, excellent chemical stability, low cost and nontoxic features, carbon dots (CDs), especially heteroatom-doped CDs, have been developed as green corrosion inhibitors, but the corrosion inhibition efficiency and underlying mechanisms of single- or dual-element doping have not yet been accurately compared and analyzed. Inspired by this, eco-friendly nitrogen-doped and nitrogen, sulfur codoped CDs (N-CDs and N,S-CDs) are prepared via a one-step hydrothermal process, and a comparative study on their inhibition performance for carbon steel corrosion in strong acidic solution is performed. The results show that both N-CDs and N,S-CDs can restrain the corrosion of carbon steel, and their inhibition efficiency increases with increasing concentration and immersion time, reaching approximately 87.9% (N-CDs) and 96.4% (N,S-CDs) at 200 ppm after 1 h of immersion. Molecular dynamics simulation indicates that the strong interaction ability between N,S-CDs and the Fe substrate leads to higher corrosion inhibition performance than the single N doping case, benefiting from the multi-anchor adsorption of N,S-CDs on carbon steel in a strong acidic solution. Therefore, the facile preparation, eco-friendliness and high corrosion inhibition performance of N,S-CDs will provide a new approach for designing highly efficient carbon dots and broadening the application of carbon dots in the corrosion field.
•Corrosion of Q235 carbon steel in 1 M HCl solution is inhibited significantly by NCDs (p-CDs and o-CDs).•The inhibition efficiency is strongly dependent on the concentration of NCDs.•The adsorption ...of NCDs involves both chemisorption and physisorption.
Nitrogen doped carbon dots (NCDs) were synthesized and used for inhibiting the corrosion of Q235 carbon steel in hydrochloric acid (HCl) solution. Inhibition effectiveness in short- and long-term immersion was examined using electrochemical measurements, weight loss and surface analysis. Results revealed the inhibition efficiency was improved significantly after adding NCDs and strongly dependent on the concentration of NCDs. SVET results showed that the sample immersed in HCl solution with NCDs showed lower anodic current density mapping than that in blank HCl solution. According to the data extracted from the Langmuir adsorption, the absorption of NCDs involved both chemisorption and physisorption.
Inspired by the high water solubility and low cytotoxicity of N doped carbon dots (CDs) prepared by using antibiotic aminosalicylic acid (ASA) as precursor, we anticipate that these CDs may possess ...an excellent protective ability to inhibit the corrosion of carbon steel in aggressive solutions owing to its special structure. Therefore, the investigation on the inhibiting effect of CDs as eco-friendly corrosion inhibitor for Q235 carbon steel corrosion in 1 M HCl solution is first reported. Electrochemical techniques, weight loss, morphological and elements characterization are combined to investigate the inhibiting effect and corrosion mechanism. The results show that corrosion of Q235 carbon steel in 1 M HCl solution is significantly inhibited by the addition of CDs, which is attributed to the formation of CDs adsorption film, and the adsorption of CDs obeys a Langmuir adsorption isotherm.
Besides, the protection efficiency increases with increasing concentration of CDs and prolonged immersion time, and reaches equilibrium eventually.
•N doped CDs have the unique structure and low toxicity.•N doped CDs can inhibit the corrosion of Q235 carbon steel in HCl solution.•The reason for this inhibition is due to the formation of CDs adsorption film.•The adsorption of CDs obeys a Langmuir adsorption isotherm.
PDF
