Pure Multi-walled Carbon Nanotubes Research Articles

Tunable optical nonlinearities of MWCNTs with core-satellite ZnS-Au structure

In order to modulate the nonlinear optical (NLO) properties of multi walled carbon nanotubes (MWCNTs) and make them applicable to ultrafast nonlinear optical devices, we fabricated a core satellite ZnS-Au nanostructure on the surface of MWCNTs via the solvothermal method. The structure and morphology of the MWCNTs-Au-ZnS product were characterized by means of the XRD, SEM and XPS, which showed that the ZnS-Au nanoassemblies were combined along with the MWCNTs through C S covalent bond and partial ionic bond. The optical nonlinearities of the MWCNTs-Au-ZnS system were investigated using the Z-scan technique under the excitation of 532 nm ps laser pulses and kinetically analyzed using the pump-probe transient absorption spectroscopy. The results showed that the saturation absorption (SA) coefficient and the third-order nonlinear susceptibility of the MWCNTs-Au-ZnS system were adjustable with the variation of the core-satellite structure. The intensity of the saturation absorption was tuned downward below that of the pure MWCNTs, while the susceptibility of the system was tuned upward above that of the pure MWCNTs, which were attributed to the combined action of two-photon absorption of ZnS, charge transfer in the system, trap states provided by Au and charge delocalization varying with the size. These tunable nonlinearities will expand the applications of the MWCNTs-Au-ZnS system in photonic devices. • Core-satellite structure of ZnS-Au is fabricated on the surface of MWCNTs via a solvothermal method. • The core-satellite structure is connected with MWCNTs via covalent bond and partial ionic bond. • The nonlinear absorption and refraction of the MWCNTs-Au-ZnS are tuned by changing the core-satellite structures.

Dynamic mechanical analysis, electrical properties and water sorption behaviour, of phenol formaldehyde nanocomposite reinforced with multiwalled carbon nanotubes

The goal of this research is to synthesise Phenol-formaldehyde nanocomposites containing pure multiwalled carbon nanotubes using an in-situ polymerisation process. The impact of filler loadings (MWCNT) with various weight percentages in the composite was explored in this research. The visco-elastic, electrical, morphological, and water sorption behaviour of the nanocomposites were investigated. The influence of MWCNT loading on the dynamic mechanical analysis, water uptake, electrical behaviour was examined. Using in-situ polymerisation, an effort was made to generate non agglomerated and homogenius dispersion of multiwalled carbon nanotubes (MWCNT) in the PF composite. The influence of MWCNT dispersion on the viscoelastic characteristics, electrical, morphological, and water sorption behaviour of PF-MWCNT nanocomposites has been thoroughly investigated. When compared to neat PF, lower filler loading (0.05 wt%, 0.08 wt percent) resulted in greater AC conductivity. According to DMA investigation of PF-MWCNT, 0.15 wt% has a greater storage modulus and 0.05 has a higher glass transition temperature. The addition of MWCNT has effectively reduced the water uptake of the entire nanocomposite.

Structural and Infrared Spectroscopy of Polyvinylpyrrolidone/Multi-walled Carbon Nanotubes Nanocomposite

In this work, polyvinylpyrrolidone (PVP)/ Multi-walled carbon nanotubes (MWCNTs) nanocomposites were prepared with two concentrations of MWCNTs by casting method. Morphological, structural characteristics and electrical properties were investigated. The state of MWCNTs dispersion in a PVP matrix was indicated by Field Effect-Scanning Electron Microscopy (FESEM) which showed a uniform dispersion of MWCNTs within the PVP matrix. X-ray Diffraction (XRD) indicate strong bonding of carbonyl groups of PVP composite chains with MWCNTs. Fourier transfer infrared (FTIR) studies shows characteristics of various stretching and bending vibration bands, as well as shifts in some band locations and intensity changes in others. Hall effect was studied to test the type of charge carriers which was shown to be P-type. The electrical conductivity was shown increased for the pure PVP and pure MWCNT from (2.047×10-5) (Ω.cm)-1 and (3.683×101) (Ω.cm)-1 to (2.51×102 and 2.36×102) (Ω.cm)-1for both concentrations of nanocomposites, which indicate the conductivity was enhancement by using the carbon nanotubes.

Performance and mechanism of CuS-modified MWCNTs on mercury removal: Experimental and density functional theory study

A functional composite adsorbent of copper sulfide (CuS) loaded on the multi-walled carbon nanotubes (MWCNTs) was successfully synthesized and used for gaseous elemental mercury (Hg0) removal. The mercury removal performance and mechanism over CuS/MWCNTs was systematically studied based on a series of experimental characterizations and density functional theory calculations. The prepared CuS/MWCNTs showed excellent elemental mercury removal ability, and the best adsorption efficiency was achieved when the loading ratio was 10% and the reaction temperature was 70℃, with an average mercury removal efficiency of 85.8% in 2 h. SO2, NO, and H2O played an inhibitory role on the mercury removal over CuS/MWCNTs. Whereas, O2 had a certain promoting effect on Hg0 removal. The TPD desorption curves and XPS analysis results showed that the Hg0 in the flue gas was attached to the adsorbent surface in the form of HgS. Density functional theory analysis showed that Hg0 was physically adsorbed in the MWCNTs, which explains low Hg0 removal efficiency of pure MWCNTs. While the chemisorption mechanism dominated the strong Hg0 adsorption on CuS surface, accompanied by the formation of oxidized HgS, which was consistent with the experimental results. Combined with the macro and micro methods, this work provides an insight into the adsorption and oxidation mechanism of elemental mercury over the CuS/MWCNTs sorbent, which can guide further sorbent designs with targeted active sites and functional groups.

Development of zinc oxide-multi-walled carbon nanotube hybrid nanofluid for energy-efficient heat transfer application: A thermal lens study

This paper addresses the need for developing an energy-efficient hybrid nanofluid with zinc oxide–multi-walled carbon nanotube (ZnO-MWCNT) for overcoming the bottleneck of efficient heat transfer in thermal systems. The concentration-dependent thermal diffusivity modifications are analyzed using the highly sensitive mode mismatched thermal lens technique. The hybrid composite is prepared by the solid-state mixing and annealing of a pure multi-walled carbon nanotube (MWCNT) and zinc oxide (ZnO), synthesized by the solution combustion method. The composite formation is studied by structural, morphological, and optical characterization techniques. Among the three nanofluids ZnO, MWCNT, and ZnO-MWCNT, the composite exhibits a drastic enhancement in thermal diffusivity at a lower solid volume fraction of 0.047 mg/ml containing 0.009 mg/ml of MWCNT. All the nanofluids show an optimum concentration beyond which the thermal diffusivity decreases with the nanoparticle concentration. Thus, this study suggests the potential application of ZnO-MWCNT hybrid nanofluids in thermal system design to enhance internal combustion engines' efficiency during cold-start.

Mechanical, thermal and gas sensing properties of flexible multi-walled carbon nanotubes/waterborne polyurethane composite film

The uniform dispersion of multi-wall carbon nanotubes (MWNTs) in waterborne polyurethane (WPU) matrix was achieved by in-situ polymerization and latex particles assisted dispersion, endowing the MWNT/WPU composite film with the enhanced tensile strength, elongation at break and thermal stability. Compared with pure WPU, the breaking strength, elongation at break and initial decomposition temperature of the MWNT/WPU composite were increased by 69.6%, 16.4% and 130 °C, respectively. The decomposition amount at 400 °C of MWNT/WPU composite is only about half that of pure WPU. The latex particles assisted dispersion also effectively improved the exposure rate of MWNTs, making it easier for MWNTs to contact the target gas molecules. Increased exposure rate and uniform dispersion of MWNTs, and rich functional groups of WPU improved the gas sensing performance, making the response of the flexible MWNT/WPU to O3 be 4.1 times of the responses of pure MWNTs. The limit of detection for O3 reached 38.4 ppb. The enhanced mechanical properties endowed the flexible MWNT/WPU composite with the high bending stability and long-term stability. After one month, the response of the MWNT/WPU was changed by 3% and the responses decreased by no more than 10% after bending 5000 times.

Effect of covalent functionalization of multi-walled carbon nanotubes with HDI trimer on mechanical properties of polyaspartate polyurea

To improve the mechanical properties of polyaspartate polyurea (PAEP), functionalized multi-walled carbon nanotubes reinforced polyurea composites (HDIT-MWCNTs/PAEP) were prepared by covalently functionalizing multi-walled carbon nanotubes (MWCNTs) with hexamethylene diisocyanate (HDI) trimer. The dispersibility, wettability and interfacial properties of HDI trimer functionalized MWCNTs (HDIT-MWCNTs) in PAEP were analyzed. The tensile properties of HDIT-MWCNTs/PAEP composites were tested and the reinforcement mechanism revealed. The results showed that compared with the pure multi-walled carbon nanotubes (P-MWCNTs), HDIT-MWCNTs were uniformly dispersed in the matrix and the wettability and interfacial properties were greatly improved. The contact angle of PAEP with HDIT-MWCNTs was 32.92°, a reduction of 46.3% compared with the P-MWCNTs. The interfacial energy and adhesion work between PAEP and HDIT-MWCNTs (25.14 mJ m−2, 95.47 mJ m−2) were 46.7% and 24.2% higher than those of P-MWCNTs. When the content of HDIT-MWCNTs was 0.5 phr, the tensile strength and Young’s modulus of the composites reached a maximum of 17.78 MPa and 170.31 MPa; an increase of 28.4% and 90.8% respectively, compared with pure PAEP. According to the cross-section of HDIT-MWCNTs/PAEP, its strengthening mechanism was mainly manifested by the deflection and bifurcation of cracks and the plastic deformation of PAEP matrix due to HDIT-MWCNTs pulling out from the matrix.

Simultaneous enhancement in thermal conductivity and flame retardancy of flexible film by introducing covalent bond connection

Owing to the high interface thermal resistance and aggregation in polymer-based materials, the thermal conductivity of multi-walled carbon nanotubes (MWCNTs) has been severely decreased in practical applications. In this work, an amino-functionalized black phosphorene (BP–NH 2 ) fabricated by ball milling has been employed to react with carboxylated multi-wall carbon nanotubes (MWCNTs–COOH) via covalent bonds to prepare a nanofiller (BP–MWCNTs) with high thermal conductivity and excellent flame retardancy. When incorporating 20.0 wt% BP–MWCNTs into cellulose nanofiber (CNF), the CNF/BP–MWCNTs 20.0 shows an in-plane thermal conductivity of 22.38 ± 0.39 W m −1 K −1 and a cross-plane thermal conductivity of 0.36 ± 0.03 W m −1 K −1 , resulting in an anisotropy index of 62.17. The effective medium theory (EMT) calculation demonstrates the interface thermal resistance is reduced to 1/39 that of pure MWCNTs, which is ascribed to the covalent bond between BP–NH 2 and MWCNTs–COOH. Simultaneously, the CNF/BP–MWCNTs 20.0 can pass the testing of UL-94 V-0 grade and the limiting oxygen index (LOI) value can be increased from 18.1% to 29.9%. Its peak of heat release rate (PHRR), total heat release (THR), smoke production rate (SPR), total smoke production (TSP), CO generated per second (COP) and CO 2 generated per second (CO 2 P) are decreased by 37.47%, 43.51%, 50.00%, 35.29%, 50.00% and 19.70%, respectively, which is due to the formation of an intumescent flame-retardant system rich in carbon source (MWCNTs), acid source (BP) and gas source (amino groups). This covalent linkage strategy offers a new thought for the preparation of flexible materials to enhance the thermal conductivity and fire resistance. • Aminated black phosphorene was successfully fabricated by ball milling. • Interface thermal resistance was significantly reduced. • Desirable thermal conductivity was obtained. • Efficient intumescent flame-retardant system was prepared.

Advanced Development of Carboxylic Acid Functionalized Multiwall Carbon Nanotubes as Safe Inhalation Drug Carrier

Background: Multiwall Carbon Nanotubes (MWCNTs) have innovative characteristic features strongly associated with nanotechnology and drug delivery applications. Objectives: The current work was performed with an objective to assess the inhalation toxicity of multi-walled carbon nanotubes. Methods: Functionalization of multi-walled carbon nanotubes was carried out by the initial basic treatment with hydrochloric acid and nearly assessed by Infrared (IR) spectroscopy, mass spectroscopy, and Transmission electron microscopy (TEM) in comparison with pure multi-walled carbon nanotubes. The acute inhalation toxicity of these functionalized and pure multi-walled carbon nanotubes was assessed in Wistar rats. The parameters: hematology, liver function test, kidney function test, and histopathology observed, evaluated and interpreted for the toxicity study. Results: The functionalized multi-walled carbon nanotubes and pure multi-walled carbon nanotubes were nearly assessed by IR spectroscopy, mass spectroscopy, and TEM. The assessments affirmed and anticipated that the pure multi-walled carbon nanotube undergoes successful functionalization. Results obtained showed a remarkable difference in the ranges of hemoglobin and platelet. The acute inhalation toxicity study did not show any toxicity of functionalized multi-walled carbon nanotubes when compared to pure multi-walled carbon nanotubes. The results of acute inhalation toxicity studies did not show any significant changes also not demonstrated hazard potential in rats following acute exposures to the functionalized multi-walled carbon nanotubes and there is no significant toxicity. Because of basic treatment during functionalization all impurity gets removed. During functionalization addition of oxygen containing group and removal of carbon dioxide group occurs. Conclusion: Functionalized multi-walled carbon nanotubes can prove to be a novel, safe, and non-toxic carrier for the delivery of drugs by inhalation route.

Respiratory and systemic impacts following MWCNT inhalation in B6C3F1/N mice

BackgroundA very pure multi-walled carbon nanotube (MWCNT) that was shown to have very low toxicity in vitro, was evaluated for lung and systemic effects and distribution following inhalation exposure.MethodsB6C3F1/N mice were exposed to varying doses (0, 0.06, 0.2, and 0.6 mg/m3) of the (99.1% carbon) MWCNT by inhalation for 30 days (excluding weekends). Ten days following the last exposure, the lungs and spleen were harvested and processed for histology and immune cell population assessment. In addition, lung lavage cells and fluid were analyzed. Stimulated Raman scattering (SRS) was used to identify particles in the lungs, spleen, kidneys, liver, mediastinal and brachial lymph nodes, and olfactory bulb. Splenic tissue sections were stained with hematoxylin and eosin (H&E) for light microscopic histopathology assessment. Blood plasma was analyzed for cytokines and cathepsins. A section of the spleen was processed for RNA isolation and relative gene expression for 84 inflammation-related cytokines/chemokines.ResultsFollowing MWCNT exposure, particles were clearly evident in the lungs, spleens, lymph nodes and olfactory bulbs, (but not livers or kidneys) of exposed mice in a dose-dependent manner. Examination of the lavaged lung cells was unremarkable with no significant inflammation indicated at all particle doses. In contrast, histological examination of the spleen indicated the presence of apoptotic bodies within T cells regions of the white pulp area. Isolated splenic leukocytes had significant changes in various cells including an increased number of proinflammatory CD11b+Ly6C+ splenic cells. The gene expression studies confirmed this observation as several inflammation-related genes were upregulated particularly in the high dose exposure (0.6 mg/m3). Blood plasma evaluations showed a systemic down-regulation of inflammatory cytokines and a dose-dependent up-regulation of lysosomal cathepsins.ConclusionsThe findings in the lungs were consistent with our hypothesis that this MWCNT exposure would result in minimal lung inflammation and injury. However, the low toxicity of the MWCNT to lung macrophages may have contributed to enhanced migration of the MWCNT to the spleen through the lymph nodes, resulting in splenic toxicity and systemic changes in inflammatory mediators.

Apigenin ameliorates oxidative stress and mitochondrial damage induced by multiwall carbon nanotubes in rat kidney mitochondria.

The toxicity of carbon nanotubes (CNTs) toward the mitochondria of the kidney is not fully recognized and still needs further research. Apigenin (APG) is known as a flavonoid compound and natural antioxidant. The purpose of this study was to assess the ameliorative role of APG against multiwall CNT(MWCNT)-induced kidney toxicity in rats. The animals were administrated with APG (10 mg/kg) for 2 weeks and then were exposed to MWCNTs (5 mg/m3 ) in pure and impure forms (10 and 100 nm) for 5 h/dayand 5 days/week. Then, mitochondria were isolated from the kidney tissue and mitochondrial toxicity parameters were measured. Decreases in succinate dehydrogenaseactivity have been reported in all groups exposed to MWCNTs. Results indicated that MWCNTs in both forms and sizes were able to increase the generation of reactive oxygen species, decline mitochondrial membrane potential, induce mitochondrial swelling, and release cytochrome c in isolated kidney mitochondria. The pretreatment of APG decreased all the abovementioned mitochondrial damage and oxidative stress parameters induced by both pure and impure MWCNTs. Our results showed that MWCNTs have the ability to enter the body, subsequently, cross cellular barriers, and reach the kidney as a sensitive organ, which can resultin mitochondrial damage in kidney cells including renal tubular cells. In addition, APG can be an effective nutritional antioxidant regimen against MWCNT-induced kidney damage.

Nanocomposites prepared from gold nanowires and multiwalled carbon nanotubes for non-enzymatic sensitive bioelectrochemical detection of pentraxin-3 in human serum

Pentraxin-3 (PTX-3) is one of the newly discovered tumor biomarker, especially in the diagnosis of lung cancer. The functionalized multi-walled carbon nanotubes (MWCNTs) and gold nanowires (AuNWs) nanocomposites decorated the PTX-3 biosensor were reported in this work, realizing ultrasensitive detection of PTX-3 in human serum through simple and effective non-enzymatic reaction. The PTX-3 biosensor has excellent electrochemical activity and biocompatibility through carbon and metal nanomaterials. Compared with pure MWCNTs, the MWCNTs combined with AuNWs which shows a wide range of detection (0.001–1000 ng ml-1), higher sensitivity (17.10 μA/(ng ml-1)/cm2) and lower detection limits (0.16 pg ml-1, S/N = 3). Meanwhile, gold nanomaterials are one of the most stable noble metal nanomaterials and MWCNTs possess large electroactive surface area, which can greatly improves the stability (96.3%, after 3 weeks) and repeatability (RSD = 0.51%). This work remarkably extends the utilization of MWCNTs and AuNWs in the construction of biosensors in the fields of biosensing and medical diagnosis.

Multi-Functional Properties of MWCNT/PVA Buckypapers Fabricated by Vacuum Filtration Combined with Hot Press: Thermal, Electrical and Electromagnetic Shielding.

The applications of pure multi-walled carbon nanotubes (MWCNTs) buckypapers are still limited due to their unavoidable micro/nano-sized pores structures. In this work, polyvinyl alcohol (PVA) was added to a uniform MWCNTs suspension to form MWCNT/PVA buckypapers by vacuum infiltration combined with a hot press method. The results showed an improvement in the thermal, electrical, and electromagnetic interference (EMI) shielding properties due to the formation of dense MWCNTs networks. The thermal and electrical properties rose from 1.394 W/m·k to 2.473 W/m·k and 463.5 S/m to 714.3 S/m, respectively. The EMI performance reached 27.08 dB. On the other hand, ABAQUS finite element software was used to simulate the coupled temperature-displacement performance. The electronic component module with buckypapers revealed a homogeneous temperature and thermal stress distribution. In sum, the proposed method looks promising for the easy preparation of multi-functional nanocomposites at low-cost.

Morphological and Electrical Properties of Multi-Walled Carbon Nanotube-based Fiber Using General Wet-spinning and Alkaline Post-treatment Methods

In this study, we report the structural features and electrical properties of a multi-walled carbon nanotube (MWCNT)-based fibers, composed entirely of MWCNTs or a large fraction of MWCNTs, using traditional fiber-manufacturing techniques inspired from classical methods applied in the creation of polyester or nylon microfibers. To obtain the MWCNT-based fibers used in this study, as-spun fibers designed to achieve 20 wt% poly(ethylene glycol)-functionalized MWCNTs and 80 wt% alkali-soluble elastomeric copolyester were prepared using a conventional wet-spinning process, and the copolyester was then sequentially removed from the as-spun fiber through an alkaline post-treatment process. As a result, we obtained a final unique MWCNT-based fiber with a MWCNT content of close to 80 wt%. The results of a morphological characterization show clearly that the surface of the fiber is mostly composed of MWCNTs with a compact structure. In addition, the MWCNT-based fiber exhibited an improved electrical conductivity of 1.9×102 S/cm, which is similar to the results of the pure or neat MWCNT-based fibers that we previously investigated. Overall, it was confirmed that the traditional approach for MWCNT-based fibers on this study have a significant potential for producing MWCNT-based fibers close to pure or neat MWCNT fibers even when using general fiber-manufacturing techniques.

Preparation of zinc tellurides quantum dots and zinc tellurides/multi-walled carbon nanotubes nanocomposites and photocatalytic activity

In this project, ZnTe quantum dots (QDs) on multi-walled carbon nanotubes (MWCNTs) by applying a facile and solvothermal method and characterized the various analysis material such as X-ray diffraction, dynamic light scattering, scanning electron microscopy, ultraviolet–visible spectroscopy. The outcomes indicated that the ZnTe QDs supported on MWCNTs in the catalyst. The ZnTe QDs on the MWCNTs, which that transport of generated electrons and leading to separation of photo-generated carriers in the coupled catalyst system. The photo-degradation performance of ZnTe–MWCNTs nanocomposites was studied by the decomposition of penicillin G (PENG) as a target compound. The results illustrated that the prepared ZnTe–MWCNTs nanocomposites exhibited higher photo-activity for the degradation of PENG than the pure ZnTe and MWCNTs under ultraviolet light irradiation. The optimal factors of PENG degradation were time: 60 min, and pH: 7.0, for the photo-degradation reaction medium.

Synthesis and characterization of functionalized MWCNTs/PMMA composites: device fabrication for RH sensing

ABSTRACT Functionalization of multiwalled carbon nanotubes (MWCNTs) with amine group using 4,4′-diaminodiphenyl sulfone (DDS) is achieved after carboxylation of pure MWCNTs (p-MWCNTs). p-MWCNTs, a-MWCNTs (acid functional MWCNTs) and f-MWCNTs (amine functional MWCNTs) were used to fabricate their nanocomposite with PMMA. A comparative study of the humidity characteristics of p-MWCNTs/PMMA, a-MWCNTs/PMMA and f-MWCNTs/PMMA-based capacitive humidity sensors was carried. f-MWCNTs/PMMA-based capacitive humidity sensor shows low hysteresis loss (5%), good response recovery behavior and highest sensitivity (S ~ 9736%) among all the studied composites. The maximum capacitance drift under different relative humidity was 1%RH.

On evaluation of thermophysical properties of transformer oil-based nanofluids: A comprehensive modeling and experimental study

Transformer oil-based nanofluids are known to have higher thermal conductivity and heat transfer performance compared to conventional transformer oils. In this study, four different types of transformer oil-based nanofluids are synthesized using the well-known two-step method. The first nanofluid contains pure multi-walled carbon nanotubes (MWCNTs), while other samples consist of 20 Vol% of MWCNTs and 80 Vol% of different oxide nanoparticles (i.e., Al2O3, TiO2, and SiO2). The dynamic viscosity and thermal conductivity of prepared samples are investigated in seven different volume fractions of 0.001, 0.0025, 0.005, 0.01, 0.025, 0.05, and 0.1%. Besides, the breakdown voltage of the pure transformer oil and nanofluids containing 0.05 and 0.1 Vol% of nanoparticles is investigated. The outcomes show that dielectric properties of hybrid carbon-based nanofluids are far better compared to those properties of the pure MWCNTs nanofluids. Finally, eight different soft computing approaches, including group method of data handling (GMDH), support vector machine (SVM), radial basis function (RBF) neural network, multilayer perceptron (MLP), and MLP and RBF models optimized with bat and grasshopper optimization algorithm (GOA), are used to model the viscosity and thermal conductivity of synthesized nanofluids. The outcomes show that the GMDH approach significantly outperforms all other models in terms of predicting the thermal conductivity and dynamic viscosity of transformer oil-based nanofluids.

Polar and Nonpolar Matrix Consisting of Twined Multiwalled Carbon Nanotube and High Nitrogen‐Doped Porous Carbon Derived from Ionic Liquid for Stable Li‐S Battery

Lithium–sulfur batteries are recognized as high energy density systems. However, due to the reproducibility of nonpolar S8, polar polysulfide intermediates and the final Li2S during cycling, developing an effective matrix to reduce sulfur consumption in the cathode and improve the cycle stability is still challenging. Herein, a polar and nonpolar matrix consisting of twined multiwalled carbon nanotube (MWCNT) and high nitrogen‐doped porous carbon is designed, in which the twined MWCNT could provide the nonpolar and physical bind, meanwhile, the N‐enriched porous carbon derived from ionic liquid could provide polar and chemical anchoring. The composite is prepared by carbonizing the 1‐ethyl‐3‐methylimidazolium dicyanamide (Emim‐dca) ionic liquid, which is loaded on the intertwined MWCNT. The ionic‐liquid‐derived composite material shows more microporous and low‐diameter mesoporous structures than intertwined MWCNT, and the nitrogen content reaches 7.42 At%. Assembled in lithium–sulfur batteries, the specific capacity of the battery reaches 1558.6 mAh g−1 at the first cycle of 0.1 C. After the 300 times cycling at 1 C, the specific capacity still remains 614.34 mAh g−1 and the attenuation is only 0.021% for each cycle. Moreover, the attenuation in the changing rate charge–discharge test is weaker than the pure intertwined MWCNT composite cathode.

Measuring surface energy of carbon nanotubes using modified washburn method

In this study, the Washburn method and Owens and Wendt model were used to estimate the surface energy of an industrial grade multiwalled carbon nanotube (MWCNT) having a carbon purity of 90%. Identical MWCNT beds were prepared and tested using seven different solvents covering wide range of surface tensions and polarities. The solvents were water, diiodomethane, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), toluene, chloroform, and n-hexane. DMF showed the highest affinity towards the MWCNT. Therefore, it was used to determine the packing constant of the MWCNT beds assuming perfect wetting between the MWCNT and DMF. The contact angles between the solvents and MWCNT were fitted using the Owens and Wendt model to calculate the dispersive and polar components of the MWCNT surface energy. The test results showed that the surface energy of the 90% carbon pure MWCNT is with dispersive and polar components of and respectively.

Comparison of Properties of the Hybrid and Bilayer MWCNTs—Hydroxyapatite Coatings on Ti Alloy

Carbon nanotubes are proposed for reinforcement of the hydroxyapatite coatings to improve their adhesion, resistance to mechanical loads, biocompatibility, bioactivity, corrosion resistance, and antibacterial protection. So far, research has shown that all these properties are highly susceptible to the composition and microstructure of coatings. The present research is aimed at studies of multi-wall carbon nanotubes in three different combinations: multi-wall carbon nanotubes layer, bilayer coating composed of multi-wall carbon nanotubes deposited on nanohydroxyapatite deposit, and hybrid coating comprised of simultaneously deposited nanohydroxyapatite, multi-wall carbon nanotubes, nanosilver, and nanocopper. The electrophoretic deposition method was applied for the fabrication of the coatings. Atomic force microscopy, scanning electron microscopy and X-ray electron diffraction spectroscopy, and measurements of water contact angle were applied to study the chemical and phase composition, roughness, adhesion strength and wettability of the coatings. The results show that the pure multi-wall carbon nanotubes layer possesses the best adhesion strength, mechanical properties, and biocompatibility. Such behavior may be attributed to the applied deposition method, resulting in the high hardness of the coating and high adhesion of carbon nanotubes to the substrate. On the other hand, bilayer coating, and hybrid coating demonstrated insufficient properties, which could be the reason for the presence of soft porous hydroxyapatite and some agglomerates of nanometals in prepared coatings.