Modification Of Multi-walled Carbon Nanotubes Research Articles

Preparation and tribological properties of modified MWCNTs by Schiff base Cu (II) complexes as lubricant additives

Four modified multi-walled carbon nanotubes (MWCNTs) with diamion-N,N′-bis (salicylidene) Schiff base Cu (II) complexes were successfully prepared by a simple and effective ultrasonic method. Friction and wear properties of 0.1 wt.% of modified MWCNTs were tested in triisodecyl trimellitate, DE and trihydroxymethylpropyl trioleate on 30 N by a microtribometer, respectively, and compared with those of graphene oxide. The structures and morphologies of the nanocomposites were investigated by Fourier-transform infrared (FTIR) spectra and transmission electron microscopy, the topography of worn surfaces of the disks were also tested by a white light interferometer. The results show that modified MWCNTs dispersed evenly and displayed better friction-reduction and anti-wear performance. As modification by a diamion-N,N′-bis (salicylidene) Schiff base Cu (II) complex can decrease twining of MWCNTs and promote its depolymerization and orderliness; Furthermore, the function as “filling” and “insulation” of modified MWCNTs between friction pairs improved the worn surface morphology. The modification of MWCNTs with o-phenylenediamine salicylaldehyde Schiff base copper (II) complex will not only promote the agglomeration of a-MWCNTs, but also indicate better tribological properties than that of graphene oxide.

Ferrocene functionalized multi-walled carbon nanotubes as supercapacitor electrodes

Modified multi-walled carbon nanotubes (MWCNTs) functionalized by a redox-active ferrocene (Fc-MWCNTs) were successfully synthesized to enhance the electrochemical performance of MWCNTs for supercapacitor application. The ferrocene moieties were attached to the surface of MWCNTs via a thiourea linker with anions-interacting capability. The Fc-MWCNTs were characterized using XPS, FTIR, SEM, TGA, DTG, and XRF methods. The electrochemical performance details were investigated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The Fc-MWCNTs electrode showed excellent capacity retention (90.8% over 5000 cycles) and a specific capacitance of 50 F g−1 at 0.25 A g−1 that is several times higher as compared to the pristine MWCNTs. The fabricated Fc-MWCNTs is proposed to be a suitable and promising candidate for energy storage material.

Electrochemical Determination of Mitomycin C and Its Interaction with Double-Stranded DNA Using a Poly(o-phenylenediamine)-Multi-Walled Carbon Nanotube Modified Pencil Graphite Electrode

The electrochemical preparation of nanostructured polymeric network consisted of poly(o-phenylenediamine)-multi-walled carbon nanotube (PoPD-MWCNT) on a disposable and commonly used pencil graphite electrode (PGE) was demonstrated. The obtained PoPD-MWCNT/PGE electrode was prepared via one-step electropolymerization using cyclic voltammetry (CV) and characterized by CV and electrochemical impedance spectroscopy (EIS). Surfaces topographies of the electrodes were investigated with scanning electron microscopy (SEM) in order to differentiate electrode modifications. The modified electrode highly improved the electrochemical properties of the PoPD/PGE and PGE. The fabrication process of the modified electrode was reproducible with a relative standard deviation of 3.8% (n = 3). Afterwards, sensitive detection of mitomycin C was performed based on the interaction of double-stranded DNA (dsDNA) immobilized on PoPD-MWCNT/PGE with mitomycin C. Thus, a detailed investigation of the interaction of dsDNA immobilized PoPD-MWCNT/PGEs with mitomycin C were also evaluated at various interaction intervals from 0 to 30 min in an efficient process. This promising electrode provided a linear concentration range for mitomycin C from 0.5 mg L−1 to 25 mg L−1 with a low limit of detection, 0.012 mg L−1, and a limit of quantification, 0.039 mg L−1, based on the guanine oxidation peaks using differential pulse voltammetry (DPV) (n = 3). The recoveries were also determined in spiked serum and satisfactory results emphasized the use of the electrode for clinical applications.

Poly(diallyldimethylammonium chloride)-grafted carboxylated-MWCNT as an additive in the polyethersulfone membrane

Surface modification of carbon nanotubes is a common method to improve their compatibility with polymer matrix in membranes. In this study, polyethersulfone (PES) nanocomposite membranes were prepared by incorporation of modified multi-walled carbon nanotubes (MWCNT). For this purpose, diallyldimethylammonium chloride was used as a monomer for the functionalization of carboxylated-MWCNT via in situ polymerization. Synthesized polymer possessed a positive charge on repeating unit, which increased the hydrophilicity of carboxylated-MWCNT. The properties and performances of the modified carboxylated-MWCNT and nanocomposite membranes were investigated by field emission scanning electron microscopy, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), contact angle measurement, salt, heavy metal, and dye removal, and fouling studies. The occurrence of the modification reaction was confirmed by FT-IR and TGA studies. Results showed that the incorporation of modified carboxylated-MWCNT into polyethersulfone membranes improved their performance in the separation of salts, heavy metal ions, and dyes. Furthermore, the surface hydrophilicity of membranes was improved by loading of modified carboxylated-MWCNT, and other properties like the pure water flux and anti-fouling resistance of PES membranes were refined remarkably. More importantly, the membranes containing modified additive showed pH sensitivity because of ammonium groups in the attached polymer chain.

Disordering of carbon nanotubes by ion bombardment

In this work, the formation of defects during the ionic modification of carbon nanotubes was studied. It was shown that during the ionic modification of multiwalled carbon nanotubes, the defect formation mechanism is reduced not only to the formation of recoil atoms by ions, but also due to the thermal peak. It can be seen that the radial distribution function for the irradiated nanotube is significantly different from the radial distribution function of a heated 4000 K nanotube. In addition, disorder has a special character: in the case of ion irradiation, in contrast to heating.

Surface modification of MWCNT with cluster form of Fe2O3/Fe3O4 NPs for improving their microwave absorption performance

The Fe2O3/Fe3O4 nanoparticles (NPs) decorated on multi-walled carbon nanotubes (MWCNTs) by a three-step synthesis method as the following: (1) Fe2O3 was produced in polyethylene glycol (PEG) matrix; (2) PEG-Fe2O3 NPs covered with Fe3O4 to obtain Fe2O3/Fe3O4 NPs; (3) MWCNTs decorated by an optimum weight ratio of the Fe2O3/Fe3O4 NPs. The produced Fe2O3/Fe3O4/MWCNT nanocomposite, in which the clusters of Fe2O3/Fe3O4 NPs decorated on the MWCNT’s surface, exhibits an excellent absorption performance and a broad effective bandwidth. The strongest reflection loss and the broadest bandwidth reached to −72.17 dB and 8.80 GHz for 2.8 mm and 2.4 mm matching thicknesses, respectively.

Transport and solvent sensing characteristics of styrene butadiene rubber nanocomposites containing imidazolium ionic liquid modified carbon nanotubes

AbstractObtaining strong interfacial interaction between filler and polymer matrix is very crucial for the fabrication of polymer nanocomposites with superior performance. Present study is aimed to fabricate high performance styrene butadiene rubber (SBR) nanocomposites with imidazolium type ionic liquid modified multiwalled carbon nanotube (MWCNT). Ionic liquid facilitates the dispersion of MWCNT in rubber matrix and it is obvious from transmission electron microscopy images. Diffusion of toluene through SBR nanocomposite membranes has been investigated as a function of surface modified MWCNT (f‐MWCNT) content to analyze the chain dynamics and filler‐polymer interactions. O2 gas barrier effect of nanocomposites with special reference to the filler loading is explored. The substantial improvement in the barrier effect in presence of filler interpreted on the grounds of a theoretical model describing permeability of heterogeneous systems. Finally solvent sensing characteristics of prepared nanocomposites are also analyzed and it is observed that prepared nanocomposites can be used as a flexible solvent sensor.

Enhancing the Mechanical Performance of Glass Fiber‐Reinforced Polymer Composites using Multi‐Walled Carbon Nanotubes

Herein, the effects of multi‐walled carbon nanotubes (MWCNTs) on the mechanical performance of glass fiber‐reinforced polymer composites (GFRPs) are investigated, and the optimized MWCNT content is obtained through a series of experiments. MWCNTs are deposited on unidirectional glass fiber cloths using a solution dip coating method. The original fiber cloths and fiber cloths deposited with MWCNTs are used to manufacture GFRPs using a vacuum‐assisted resin injection process. The GFRP specimens are then synthesized to characterize the tension, bending, interlaminar shear strength, and mode‐II fracture toughness by uniaxial tension, three‐point bending, short beam shear, and end notch flexural tests. The results confirm that the mechanical performance of the original GFRPs increases with the addition of MWCNTs, and GFRPs with an MWCNT content of 0.3 wt% exhibit better comprehensive mechanical properties. Scanning electron microscopy is used to analyze the damage mechanism of the broken specimens with and without MWCNT modification.

Metal Phthalocyanine Modified Multi Walled Carbon Nanotubes; DC-Conductivity and Optical Properties

Hybrid materials of multi walled carbon nanotubes-zinc phthalocyanine (MWCNTs-ZnPc) and multi walled carbon nanotubes-aluminum phthalocyanine (MWCNTs-AlPc) have been prepared. MWCNTs were treated with mixture of nitric and sulfuric acid pre to the mixing with phthalocyanines for the de-bundling effect. Hybrid materials have been drop casted onto glass slides and interdigitated electrodes from their solution in dimethylformamide. UV-visible absorption spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR) have revealed the successful hybridization due π-π interaction between MWCNTs and phthalocyanine species. I-V measurements and DC conductivity of the hybrid films has been investigated. The behavior of DC electrical conductivity and the activation energy with the variation of temperature were studied.

Surface modification of multiwalled carbon nanotubes via surface RAFT copolymerization method and capecitabine-loaded anticancer hydrogel for controlled drug delivery in stomach

ABSTRACT In our work, reversible addition-fragmentation chain transfer (RAFT)/carbon nanotube (CNT)/acrylic acid (AA)/acrylamide (AAm) nanocomposite was synthesized by living radical polymerization. The structure and surface morphology of the synthesized RAFT-CNT-Hydrogel nanocomposites were analyzed by FTIR, 1HNMR, SEM, TEM, XRD, and TGA/DTG techniques. The results indicated that PAA/AAm chains grafted with CNT by RAFT polymerization. RAFT-CNT-Hydrogel nanocomposites for drug release investigated in different buffers resulted in a strong pH-sensitive behavior. In total, the obtained hydrogel drug-delivery systems are presented a proper effect versus stomach cancer in vitro and in vivo, and it can be used as candidates for controlled release of anticancer drugs in stomach with exalted remedial agents.

Fabrication of highly sensitive Bisphenol A electrochemical sensor amplified with chemically modified multiwall carbon nanotubes and β-cyclodextrin

Bisphenol A (BPA), one of the most extensively used plasticizers, is an endocrine disrupting chemical (EDC). Leaching of BPA in food, and water sources causes adverse health effects, therefore, it requires monitoring. In this work, we developed a simple, low-cost electrochemical sensor for detecting a very low level of BPA in water using chemically modified multiwall carbon nanotubes (MWCNTs) with β-cyclodextrin (βCD) on screen-printed carbon electrode (SPCE). The electrochemical sensing of BPA showed a completely irreversible process with diffusion-controlled oxidation involving two electrons and two protons. At an optimized condition, the sensor showed a two-step linear response from 125 nM to 2 μM and 2 to 30 μM, with correlation coefficients of 0.997 and 0.995, respectively. The limit of detection for BPA was determined to be 13.76 nM (SNR = 3). The improved sensing performance is attributed to host-guest interaction ability of MWCNTs- βCD with BPA due to the combined effect of hydrophilic behavior of βCD and large surface area of MWCNTs. The sensors exhibited an excellent reproducibility (RSD = 4.7 %) and stable response over five weeks and negligible interference with common chemical species in water. The sensor’s reliability test in lake and tap water showed an excellent recovery of BPA ranging from 96.05 %–108.70 %. These favorable results can enable the development of simple and cheap portable sensors for monitoring a wide range of BPA levels in the water.

Ultrasonic assisted synthesis of a novel ternary nanocomposite based on carbon nanotubes/zeolitic imidazolate framework-67/polyaniline for solid-phase microextraction of organic pollutants

In the present research, a new nanoporous composite coating of polyaniline (PANI), modified multi-walled carbon nanotubes (MWCNTs), and zeolitic imidazolate frameworks (ZIF) was successfully fabricated by a layer-by-layer strategy through electrodeposition method on a stainless steel wire and ultrasonic-assisted. The optimization of the coating was done with design expert 10.0.7.0 software, while the crucial factors were optimized using a central composite design (CCD). The characteristics of the nanocomposite were examined by field emission-scanning electron microscopy (FE-SEM) and Fourier transform-infrared spectroscopy (FT-IR). The applicability of this home-made coating fiber was assessed for the headspace solid-phase microextraction (HS-SPME) of trace amounts of some organic pollutants in aqueous samples followed by gas chromatography-flame ionization detector (GC-FID). The significant parameters affecting the extraction efficiency, such as desorption and sorption conditions along with ionic strength, were also investigated. Validation experiments showed that the optimized method has wide linear ranges from 0.005 to 1000 μg L−1, very low limits of detection (0.0003–0.0008 μg L−1) and excellent repeatability (0.2–9.7%). The relative recoveries obtained by spiking the target analytes in aqueous samples were in the range 83.4–111.2%. The combination of modified CNTs, ZIF-67, and aniline in the nanocomposite create attractive opportunities for the development a new coating fiber with a porous structure, strong adhesion to the surface of the wire, excellent thermal stability, long lifespan and high extraction efficiency suggesting the potential of this SPME fiber for routine analysis in real samples.

Molecularly Imprinted Voltammetric Sensor Based on Chitosan-CNTs Decorated with AuNPs Nanocomposite for Catechol Detection

This research is based on the development of a novel, biocompatible and sensitive electrochemical imprinted sensor based on the detection of a phenolic compound, such as catechol, employing electroactive nanomaterials with the objective of improving the electron transfer between the electrode surface and the solution [1] and a natural biopolymer due to its excellent layer forming ability [2]. The development of the sensor is based on the modification of multiwalled carbon nanotubes (MWCNTs) with gold nanoparticles (AuNPs). The decorated MWCNTs have been recovered with a polymeric chitosan (CS) matrix generating a nanocomposite that contains the electroactive material inside. The polymeric matrix of CS that holds the modified MWCNTs has been electrodeposited in the presence of the phenolic compound on a boron doped diamond (BDD) electrode. The sensor surface has been structurally characterized to demonstrate the correct adsorption of the film and the correct recovery of the decorated carbon nanotubes on the BDD electrode surface. The performance as an electrochemical MIP sensor analyzed by cyclic voltammetry has offered excellent characteristics, demonstrating a high affinity to catechol with high selectivity, reproducibility, repeatability and sensitivity in the range of catechol concentrations from 0 to 1 mM. Finally, the implementation of the sensor to measure in a complex red wine sample has been carried out. The obtained results have resulted to be successful to quantify catechol in the real matrix. For these reasons, the proposed research manifests a promising and interesting way to implement an imprinting biocompatible polymers method in the development of an electrochemical sensor for phenols detection in the 4.0 industry.[1] S. A. Zaidi, Sensors Actuators B. Chem., 2018, 265,488-497.[2] A. Gopalan, S. Komathi, N. Muthuchamy, K. Lee, M. J. Whitcombe, L. Dhana, y G. Sai-anand, Prog. Polym. Sci., 2019 88, 1-129. Acknowledgments: Financial support by MINECO and FEDER (RTI2018-097990-B-100 and BES-2016-077825) and the Junta de Castilla y León-FEDER (VA-275P18) is gratefully acknowledged.

Effect of surface oxygen groups in the electrochemical modification of multi-walled carbon nanotubes by 4-amino phenyl phosphonic acid

Electrochemical functionalization of pristine Multi-walled Carbon Nanotubes (MWCNTs) and oxidized MWCNTs by nitric acid with 4-aminophenyl phosphonic acid (4-APPA) has been studied. Electrochemical modification has been carried out by cyclic voltammetry using different upper potential limits, what results in the incorporation of N and P functionalities through oligomerization and covalent attachment. The electrochemical characterization shows that there are important differences among the functionalized materials derived from the pristine MWCNTs or the oxidized materials. For the pristine MWCNTs, well-defined redox processes are observed. Characterization by X-Ray photoelectron spectroscopy, Raman spectroscopy and electron microscopy, show that oligomerization is easier for the pristine MWCNTs and the presence of oligomer chains are clearly distinguished for the lowest oxidation potentials. However, the presence of surface oxygen groups in the oxidized MWCNTs modify the interaction of the 4-APPA with the surface promoting mainly covalent attachment.

Room temperature hydrogen storage in modified vertically-aligned carbon nanotubes forest measured in vacuum by a langasite microbalance

A storage capacity of hydrogen in multi-wall carbon nanotubes (MWCNTs) forest has been investigated experimentally using a langasite oscillator from vacuum to 100 kPa at room temperature. MWCNTs were directionally grown on the langasite oscillator using chemical vapor deposition at 750 °C, where langasite retains its oscillating property. Modification of MWCNTs on the langasite oscillator were conducted by atomic oxygen irradiation to induce the open-ended structure of the MWCNTs. The hydrogen storage capacities of MWCNTs directly grown on the oscillator were successfully evaluated, and the maximum hydrogen storage capacity was improved 60% with the modification of MWCNTs by atomic oxygen irradiation.

Surface modification of multiwall carbon nanotubes by electrochemical anodic oxidation

The surface modification of multiwall carbon nanotubes (MWCTNs) was achieved by electrochemical anodic oxidation in NaOH and H2SO4 electrolytes. Their defect structures, functional groups, morphology and dispersibility in aqueous solutions were characterized by SEM, TEM, XPS, FTIR, Raman spectroscopy, zeta potential analysis and a stability test of their suspensions. Results indicate that anodic oxidation with the NaOH electrolyte removes more amorphous carbon, introduces fewer defects and more oxygen-containing functional groups (mainly -OH), and produces shorter nanotubes, as a result of which the resulting nanotubes are more stable when dispersed in aqueous solutions compared with those oxidized by the H2SO4 electrolyte. MWCTNs are more easily oxidized in the NaOH electrolyte, and the numbers of oxygen-containing functional groups and hydroxyl groups increase continuously with the oxidation degree. In the H2SO4 electrolyte, however, the numbers of oxygen-containing functional groups and hydroxyl groups increase and level off with the oxidation degree.

Effects of Ni modified MWCNTs on the microstructural evolution and shear strength of Sn-3.0Ag-0.5Cu composite solder joints

A composite solder was prepared by adding different amount Ni modified multi-walled carbon nanotubes (MWCNTs) into the Sn-3.0Ag-0.5Cu (SAC305) solder. Experiments were conducted to investigate the thermal behavior, mechanical properties of composite solder alloys, shear fracture behavior of solder joints were evaluated as well. The modification process was carried out on the MWCNTs using electroless modification method to synthesis the Ni modified carbon nanotubes (Ni-CNTs), which was manually mixed into SAC305 solder powder with different amount. The melting point of the composite solder alloys was slightly increased with the increment of the amount of Ni-CNTs. The nanoindentation test results confirmed that the hardness and modulus of composite solder alloys were enhanced after the addition of Ni-CNTs. The aging experiment was implemented for the joints and the results indicated that the Ni-CNTs could effectively inhibit the growth of IMC layer as an additive in SAC305 solder. The shear strength of SAC305-xNi-CNTs/Cu (x = 0, 0.1 and 0.2 wt.%) joints was reinforced with the increment of Ni-CNTs amount. Furthermore, the SAC305-0Ni-CNTs/Cu and SAC305-0.1Ni-CNTs/Cu solder joints were broken partially between the solder and IMC, mostly between the solder matrix, and SAC305-0.2Ni-CNTs/Cu solder joint was broken completely inside solder matrix. It was suggested that the fracture mode of the solder joints changed from mix fracture mode to ductile fracture mode as the amount of Ni-CNTs increased.

Modified multi-walled carbon nanotubes assisted foam fractionation for effective removal of acid orange 7 from the dyestuff wastewater

In this study, multi-walled carbon nanotubes (MWCNTs) had been used to strengthen the removal of acid orange 7 (AO7) from the dyestuff wastewater by using foam fractionation. First, the surface modification of MWCNTs was performed by introducing hypochlorite groups (-OCl). The modified MWCNTs were characterized by using SEM, XRD, FTIR and Raman spectroscopy. Subsequently, the potential of modified MWCNTs as a novel collector for AO7 adsorption was examined. The adsorption conditions of modified MWCNTs towards AO7 were optimized by using response surface methodology (RSM) with a central composite design (CCD). The adsorption capacity of modified MWCNTs towards AO7 could reach 47.72 ± 0.79 mg·g−1 under the optimum conditions. The kinetics and the equilibrium adsorption data were analyzed by using different kinetic and isotherm models. According to the regression results, adsorption kinetics data were well described by pseudo-second order model, whereas adsorption isotherm data were best represented by Langmuir isotherm model. Finally, foam fractionation was performed with a batch mode. Under the suitable conditions of loading liquid volume 300 mL, modified MWCNTs dosage 180 mg, cetyltrimethylammonium bromide (CTAB) concentration 50 mg·L−1, AO7 concentration 30 mg·L−1, pore diameter of gas distributor 0.125 mm and air flow rate 100 mL·min−1, the removal percentage and enrichment ratio of AO7 were 91.23% and 6.17, respectively. The decolourization ratio of solution after foam fractionation was found to be 98.66%.

A simple strategy based on fibers coated with surfactant-functionalized multiwalled carbon nanotubes to improve the properties of solid-phase microextraction of phenols in aqueous solution

Methods and experimentsIn this study, a functionalized multiwalled carbon nanotube (MWCNT)-coated solid-phase microextraction (SPME) fiber was developed for concentrating analytes in aqueous samples. Sodium deoxycholate (NaDC) was used as a dispersing agent for non-covalent modification of MWCNTs. The coating showed porous structure and large adsorption capacity. To investigate the capability of this MWCNTs/NaDC SPME fiber, it was applied to the analysis of phenols in aqueous solution. After extraction, the analytes were desorbed in an acetonitrile–water solution and analyzed using high-performance liquid chromatography.ResultsThe MWCNTs/NaDC fiber exhibited good analytical performance, and fine preparation reproducibility was obtained with the relative standard deviations (RSDs) ranging from 4.9% to 10.2% (n = 6) in one batch, from 5.7% to 11.9% (n = 3) among different batches. Under the optimum extraction conditions, the detection limits were 0.15–0.30 ng/mL(S/N = 3), the linear detection ranges were 1–100 ng/mL (R2 ≥ 0.9997) for these analytes, and good recoveries (80.3–95.4%) were obtained for the spiked samples.ConclusionThis is a simple and accurate pretreatment method for the analysis of phenols in aqueous samples.

The effect of the geometry and content of the modified carbon nanotubes on the thermal properties of the composite phase-change materials

In this paper, ultrasonic dispersion and surface chemical modification were used to prepare the modified multi-walled carbon nanotubes (MWNTs)/paraffin composite phase-change materials (PCMs). The surface modification of MWNTs was developed via coating MWNTs with silica dioxide. The modified MWNTs were marked as SiO2@MWNTs. The phase-change properties, thermal stability and chemical functional groups of the MWNTs/paraffin composite PCMs were measured by differential scanning calorimetry, thermogravimetric analysis (TG) and Fourier transform infrared spectroscopy, respectively. The results indicated that paraffin and MWNTs were compound physically. The diameter and content of MWNTs had influence on the phase-change temperature and the latent heat of the MWNTs/paraffin composite PCMs. The smaller the diameter or larger content of the SiO2@MWNTs, the greater the influence was. The reduction degree of PCM1(the diameter of the SiO2@MWNTs is 20–30 nm) in latent heat is about 4.5 times of that of PCM3(the diameter of the SiO2@MWNTs is larger than 50 nm). The thermal stability and the thermal conductivity of the composite PCMs were improved with the addition of the SiO2@MWNTs. When the content of SiO2@MWNTs is 5 mass%, the thermal conductivity of the paraffin PCMs is 0.383 W m−1 K−1).