Various Types Of Carbon Nanotubes Research Articles

Analysis of carbon nanotube for low power nano electronics applications

The implementation of nanoelectronic circuits depends on technologies such as Complementary Metal-Oxide Semiconductor (CMOS) or Bipolar CMOS (BICMOS), and the length of the channel can be reduced up to a certain limit. Due to the generation of various errors nanomaterials can be an alternative solution for circuit design. In the field of nanotechnology, Carbon Nanotubes (CNTs) have become a notable and remarkable invention. Their structure is very similar to that of graphite, and its small size, lightweight, high strength, and good conductivity make them ideal building blocks for future technologies. CNTs hold great promise for being the catalyst for the next technological revolution. Today, a broad range of processes is available to produce various types of CNTs, depending on the rolling times of graphite sheets. This review paper sheds light on the different types of CNTs, their properties, methods of synthesis such as arc discharge and chemical vapor deposition, and their applications. To achieve this goal, this paper provides a review that aims to define the state-of-the-art in this field from a novel and unified perspective while elaborating insights of current developments and emerging trends.

An overview of theoretical investigations on interaction of drug molecule with functionalized carbon nanotubes as drug delivery system

CNTs are promising nano-carriers for both drugs as well as biomolecules. This study possesses in-depth knowledge and understanding of carbon nanotubes both for their pharmaco-toxicological properties in drug molecule, it is essential to recommended for routine clinical use in the form of drug delivery carriers in the diagnosis and treatments of many diseases. The surface modified or functionalized Carbon nanotubes (CNTs) can be used for different purposes like improving solubility, carrying various therapeutic, and targeting agents. The functionalization of CNTs can be done via covalent or noncovalent bonding. The Density functional theory calculations are very much helpful to understand the effects on covalently binding of drug molecule with functionalized carbon nanotubes and fullerenes. The present review focus on the structural stability of drug molecule and adsorption behaviour of molecules over various types of CNTs. In addition, progress in carbon nanotube technology may well lead to better insights into biological and physical chemistry processes through theoretical calculations. This will make it possible to find drug molecules more compatible with carbon nanotube to facilitate in medical field.

Eco-friendly synthesis of carbon nanotubes and their cancer theranostic applications.

Carbon nanotubes (CNTs) with attractive physicochemical characteristics such as high surface area, mechanical strength, functionality, and electrical/thermal conductivity have been widely studied in different fields of science. However, the preparation of these nanostructures on a large scale is either expensive or sometimes ecologically unfriendly. In this context, plenty of studies have been conducted to discover innovative methods to fabricate CNTs in an eco-friendly and inexpensive manner. CNTs have been synthesized using various natural hydrocarbon precursors, including plant extracts (e.g., tea-tree extract), essential oils (e.g., eucalyptus and sunflower oil), biodiesel, milk, honey, and eggs, among others. Additionally, agricultural bio-wastes have been widely studied for synthesizing CNTs. Researchers should embrace the usage of natural and renewable precursors as well as greener methods to produce various types of CNTs in large quantities with the advantages of cost-effectiveness and environmentally benign features. In addition, multifunctionalized CNTs with improved biocompatibility and targeting features are promising candidates for cancer theranostic applications owing to their attractive optical, chemical, thermal, and electrical properties. This perspective discusses the recent developments in eco-friendly synthesis of CNTs using green chemistry-based techniques, natural renewable resources, and sustainable catalysts, with emphasis on important challenges and future perspectives and highlighting techniques for the functionalization or modification of CNTs. Significant and promising cancer theranostic applications as well as their biocompatibility and cytotoxicity issues are also discussed.

An overview on carbon nanotubes as innovative absorbent for marine oil spill

Marine oil spills due to drilling activities is a serious problem worldwide because it poses a major risk to marine ecosystem. So far, researchers in the world continues to innovate materials to clean up marine oil spills. Among them, based on carbon nanotubes. Carbon nanotubes are known have perfect ability to absorb oil and neutralize substance. This study review provides the various types of carbon nanotubes that have best quality to absorb marine oil spills. Continue with various types of carbon nanotubes technology, which technology should be developed in the future by considering each advantage possessed by of carbon nanotubes in order to create product innovation that efficient and environmentally friendly because does not make some new pollution. Therefore, carbon nanotubes is a good choice material to clean up marine oil spills.

Multi‐Fidelity High‐Throughput Optimization of Electrical Conductivity in P3HT‐CNT Composites

AbstractCombining high‐throughput experiments with machine learning accelerates materials and process optimization toward user‐specified target properties. In this study, a rapid machine learning‐driven automated flow mixing setup with a high‐throughput drop‐casting system is introduced for thin film preparation, followed by fast characterization of proxy optical and target electrical properties that completes one cycle of learning with 160 unique samples in a single day, a >10× improvement relative to quantified, manual‐controlled baseline. Regio‐regular poly‐3‐hexylthiophene is combined with various types of carbon nanotubes, to identify the optimum composition and synthesis conditions to realize electrical conductivities as high as state‐of‐the‐art 1000 S cm−1. The results are subsequently verified and explained using offline high‐fidelity experiments. Graph‐based model selection strategies with classical regression that optimize among multi‐fidelity noisy input‐output measurements are introduced. These strategies present a robust machine‐learning driven high‐throughput experimental scheme that can be effectively applied to understand, optimize, and design new materials and composites.

Unique sliding properties of bucky paper and a simple method to control the sliding angle

In this study, an easy and widely applicable method to control the sliding angle of bucky paper (BP), which is a paper-like membrane consisting of carbon nanotubes (CNTs), while maintaining the hydrophobic properties was developed. We prepared BPs using various types of CNTs, and the contact angle insignificantly differs regardless of the type of CNT, but the sliding angle shows a notable difference. The sliding angle of the BP (2°–3°) indicates an excellent water sliding ability for short CNTs, whereas the water droplet on the BP with long CNTs did not slip-down, not even at 90°. By utilizing this feature for hybrid long and short CNTs, the sliding angle can be controlled from 2° to 90° using the CNT ratio.

Carbon nanotube dielectrophoresis: Theory and applications

Carbon nanotubes (CNTs) are one of the most extensively studied nanomaterials in the 21st century. Since their discovery in 1991, many studies have been reported advancing our knowledge in terms of their structure, properties, synthesis, and applications. CNTs exhibit unique electrothermal and conductive properties which, combined with their mechanical strength, have led to tremendous attention of CNTs as a nanoscale material in the past two decades. To introduce the various types of CNTs, we first provide basic information on their structure followed by some intriguing properties and a brief overview of synthesis methods. Although impressive advances have been demonstrated with CNTs, critical applications require purification, positioning, and separation to yield desired properties and functional elements. Here, we review a versatile technique to manipulate CNTs based on their dielectric properties, namely dielectrophoresis (DEP). A detailed discussion on the DEP aspects of CNTs including the theory and various technical microfluidic realizations is provided. Various advancements in DEP-based manipulations of single-walled and multiwalled CNTs are also discussed with special emphasis on applications involving separation, purification, sensing, and nanofabrication.

High-Performance Ultraviolet Photodetector Based on a Zinc Oxide Nanoparticle@Single-Walled Carbon Nanotube Heterojunction Hybrid Film.

A hybrid film consisting of zinc oxide nanoparticles (ZnO NPs) and carbon nanotubes (CNTs) is formed on a glass substrate using a simple and swift spin coating process for the use in ultraviolet photodetectors (UV PDs). The incorporation of various types of CNTs into ZnO NPs (ZnO@CNT) enhances the performance of UV PDs with respect to sensitivity, photoresponse, and long-term operation stability when compared with pristine ZnO NP films. In particular, the introduction of single-walled CNTs (SWNTs) exhibits a superior performance when compared with the multiwalled CNTs (MWNTs) because SWNTs can not only facilitate the stability of free electrons generated by the O2 desorption on ZnO under UV irradiation owing to the built-in potential between ZnO and SWNT heterojunctions, but also allow facile and efficient transport pathways for electrons through SWNTs with high aspect ratio and low defect density. Furthermore, among the various SWNTs (arc-discharged (A-SWNT), Hipco (H-SWNT), and CoMoCat (C-SWNT) SWNTs), we demonstrate the ZnO@A-SWNT hybrid film exhibits the best performance because of higher conductivity and aspect ratio in A-SWNTs when compared with those of other types of SWNTs. At the optimized conditions for the ZnO@A-SWNT film (ratio of A-SWNTs and ZnO NPs and electrode distance), ZnO@A-SWNT displays a sensitivity of 4.9 × 103 % with an on/off current ratio of ~104 at the bias of 2 V under the UV wavelength of 365 nm (0.47 mW/cm2). In addition, the stability in long-term operation and photoresponse time are significantly improved by the introduction of A-SWNTs into the ZnO NP film when compared with the bare ZnO NPs film.

A molecular dynamics simulation of the glass transition temperature and volumetric thermal expansion coefficient of thermoset polymer based epoxy nanocomposite reinforced by CNT: A statistical study

A molecular dynamics simulation study is performed to predict the glass transition temperature ( Tg) and the volumetric coefficient of thermal expansion (CTE) of thermoset polymer based nanocomposite reinforced by carbon nanotube (CNT). An atomistic model of cross-linked Diglycidyl ether bisphenol A (DGEBA) epoxy and Diethylenetriamine (DETA) was built as a matrix by employingCondensed-phase optimized molecular potentials for atomistic simulation (COMPASS27) force field. Different molecular models were constructed with various types of CNT embedded in epoxy simulation boxes. Tg was determined based on density variation with temperature. Furthermore, a new method is proposed to compute the CTE based on density variation with temperature. The effects of CNT diameter, volume fraction and chirality on Tg and CTE of nanocomposites were investigated using molecular dynamics simulation. For all cases, studied and CTE were less than pure epoxy (between 3.77% to 10.05% for Tg and respectively 14.24% to 32.23% and 23.82% to 41.65% for CTE below and above of Tg ). Increasing the CNT diameter in nanocomposite increases Tg and CTE (5.0% for Tg and 20.0% for CTE when the diameter of CNT changed 7.8A0 to 15.6A0). On the other hand increasing volume fraction of CNT in the nanocomposite decreases Tg and CTE (2.7% for Tg and 13.8% for CTE when the volume fraction of CNT in the nanocomposites changed 3.36% to 5.23%). Chirality studies under constant weight fraction of nanocomposites show that applying armchair CNT instead of zigzag CNT, decreases Tg and increases CTE (2.1% for Tg and 5.8% for CTE)

Fabrication of Various Carbon Nanotube/Nickel Nanocomposite Powders by Polyol Process.

We developed a molecular level mixing process for fabricating various types of carbon nanotube (CNT)/nickel (Ni) nanocomposite powders by a polyol process. A CNT/Ni nanocomposite was fabricated by two steps, dehydration of polyol and oxidation of acetaldehyde with the formation of diacetyl. Oxygen functionalized CNTs offer direct nucleation sites for Ni particles and strong chemical bonding between CNT and Ni particles. By controlling nucleation sites and nuclear growth, we successfully fabricated three different types of nanocomposite powders, CNT implanted Ni, Ni coated CNTs, and Ni decorated CNTs. Each type of powder was developed for various applications. During the sintering process, the implanted type retained CNT's crystal structure. As a conductive filler to other matrix, the coated and decorated type offered homogeneous dispersion and an enhanced conductive network. Various types of CNT/Ni nanocomposite powders show potential for remarkable development of bulk scale fabrication where exceptionally high strength and electric conductivity is necessary.

Diameter-Dependent Degradation of 11 Types of Carbon Nanotubes: Safety Implications

Understanding the biodegradation profiles of various types of carbon nanotubes (CNTs) is important for their safe use according to their structural characteristics. To investigate the relationship between the biodegradation and the physicochemical properties of CNTs, sodium hypochlorite was used to degrade CNTs because it is believed to be a key oxidizer of CNTs inside macrophages and neutrophils. The complete degradation of CNTs in response to sodium hypochlorite was confirmed, and the half-lives of 11 different types of commercially available single-wall CNTs (SWNTs), carbon nanohorns (CNHs), and multiwall CNTs (MWNTs) in sodium hypochlorite were determined. The degradation of CNTs generally correlated with diameter, as follows: SWNTs ≥ CNHs > thinner MWNTs > thicker MWNTs. In addition, defects and the degree of dispersion also affected the degradation rate, but these were not the primary factors determining CNT degradation.

Multivariate calibration for carbon nanotubes in the environment using the microwave induced heating method

With continuous increase in production and application of various types of carbon nanotubes (CNTs), the presence of a mixture of different types of CNTs in the environment cannot be neglected. Since distinct types of CNTs have different influences on environmental and human health, the environmental quantification of each type of CNTs has become a critical step in all CNTs-related studies. However, most of existing quantification methods have not been implemented to determine mass/concentration of individual type of CNTs in multi-component samples. Therefore, the goal of the present paper is to develop Chemometrics-based multivariate calibration approaches for simultaneously quantifying individual type of CNTs in the environment with the microwave induced temperature rise spectra. Motivated by successful applications of partial least square regression (PLS), least square-support vector machine (LS-SVM) and artificial neural networks (ANN) in measuring specific contaminants in mixtures, the potential of applying these techniques in predicting quantities of Single-walled CNTs, Multi-walled CNTs and carboxylate Multi-walled CNTs in environmental matrices (agricultural soil and anaerobic sludge) was investigated in this study. Our results revealed that the developed LS-SVM model presented high R2 and low root mean square error of prediction (RMSEP) in both 2-component and 3-component matrices, while the resulted ANN model was only accurate in the 2-component matrix. The PLS model was found to be ineffective in interpreting relationship between the microwave induced temperature rises and mass of CNTs as indicated by small R2 and large RMSEP.

Enhanced field emission properties of carbon nanotube bundles confined in SiO2 pits

It has been widely reported that carbon nanotubes (CNTs) exhibit superior field emission (FE) properties due to their high aspect ratios and unique structural properties. Among the various types of CNTs, random growth CNTs exhibit promising FE properties due to their reduced inter-tube screening effect. However, growing random growth CNTs on individual catalyst islands often results in spread out CNT bundles, which reduces overall field enhancement. In this study, significant improvement in FE properties in CNT bundles is demonstrated by confining them in microfabricated SiO2 pits. Growing CNT bundles in narrow (0.5 μm diameter and 2 μm height) SiO2 pits achieves FE current density of 1–1.4 A cm−2, which is much higher than for freestanding CNT bundles (76.9 mA cm−2). From the Fowler Nordheim plots, confined CNT bundles show a higher field enhancement factor. This improvement can be attributed to the reduced bundle diameter by SiO2 pit confinement, which yields bundles with higher aspect ratios. Combining the obtained outcomes, it can be conclusively summarized that confining CNTs in SiO2 pits yields higher FE current density due to the higher field enhancement of confined CNTs.

Mechanisms of carbon nanotube-induced pulmonary fibrosis: a physicochemical characteristic perspective.

Carbon nanotubes (CNTs) are engineered nanomaterials (ENMs) with numerous beneficial applications. However, they could pose a risk to human health from occupational or consumer exposures. Rodent models demonstrate that exposure to CNTs via inhalation, instillation, or aspiration results in pulmonary fibrosis. The severity of the fibrogenic response is determined by various physicochemical properties of the nanomaterial such as residual metal catalyst content, rigidity, length, aggregation status, or surface charge. CNTs are also increasingly functionalized post-synthesis with organic or inorganic agents to modify or enhance surface properties. The mechanisms of CNT-induced fibrosis involve oxidative stress, innate immune responses of macrophages, cytokine and growth factor production, epithelial cell injury and death, expansion of the pulmonary myofibroblast population, and consequent extracellular matrix accumulation. A comprehensive understanding of how physicochemical properties affect the fibrogenic potential of various types of CNTs should be considered in combination with genetic variability and gain or loss of function of specific genes encoding secreted cytokines, enzymes, or intracellular cell signaling molecules. Here, we cover the current state of the literature on mechanisms of CNT-exposed pulmonary fibrosis in rodent models with a focus on physicochemical characteristics as principal drivers of the mechanisms leading to pulmonary fibrosis. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Respiratory Disease Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

Global transcriptional responses of denitrifying bacteria to functionalized single-walled carbon nanotubes revealed by weighted gene-coexpression network analysis

Functionalized single-walled carbon nanotubes (f-SWNTs) are widely used in many fields due to the unique structure and the excellent properties. Although these nanomaterials have been reported to enable to cause negative effects on denitrifying bacteria once they enter the environment, the toxic behaviors and regulatory mechanisms of f-SWNTs to denitrification remain unclear. In this study, the denitrification performance of a model denitrifier exposed to pristine and functionalized SWNTs was investigated, and the global transcriptional responses were comprehensively explored by RNA-seq and weighted gene-coexpression network analysis (WGCNA). Although both hydroxyl SWNTs (SWNTs-OH) and carboxyl SWNTs (SWNTs-COOH) showed inhibitory effects on bacterial denitrification, the former more severely inhibited denitrification than the latter. Transcriptional profiles showed that compared with SWNTs-COOH, SWNTs-OH much more strongly influenced the expressions of the key genes related to signal transduction, substance transport, electron transfer and transcriptional regulation. Functional analysis further indicated that the genes associated with substrate transport, carbon source metabolism and electron transfer underwent dramatic down-regulation. Using WGCNA, 12 gene modules were established corresponding to various types of carbon nanotubes, and eigengene adjacency analysis revealed the key gene modules related to denitrification performance under different conditions. Hub gene network analysis revealed the key regulatory factors of bacterial denitrification induced by f-SWNTs. The results suggested that f-SWNTs modulated the key genes responsible for the glycerolipid/free fatty acid (GL/FFA) cycle, and thus disturb processes associated with denitrification, including signaling process, energy homeostasis, intracellular redox balance and transportation.

Carbon nanotube size effect on the mechanical properties and toughness of nanocomposites

To evaluate the nanotube size effect on the material properties of nanotube‐modified nanocomposites, two types of multi‐walled carbon nanotubes with various dimensions were used to form nanocomposites, and then the mechanical properties and the toughness were measured. The well‐known issue of nanotube dispersion was examined using various microscopic observations, and an ideal dispersion process was identified. The results revealed that adding nanotubes led to increases in the Young's modulus and toughness of the nanocomposites. A maximum measured value of the fracture energy was recorded at 237 J m−2 for the nanocomposite toughened with 0.5 wt% of the longer nanotubes. This is ∼90% higher than the unmodified epoxy, and a 40% increase in the fracture energy compared with the sample containing the shorter nanotubes under identical nanotube loading. This indicated that the length of the nanotubes severely affected the toughness of the nanotube‐modified polymers. However, the increased moduli, triggered by the addition of the various types of carbon nanotubes, were similar. The toughening mechanisms were identified via studying the fracture surfaces of the nanocomposites. POLYM. COMPOS., 39:E1072–E1086, 2018. © 2017 Society of Plastics Engineers

Application of different types of carbon nanotubes as PIGE surface modifier in Pd(II) electrochemical determination

ABSTRACTNowadays, carbon nanotubes with differences in specific surface area, dopants, or functional groups are used in a number of applications, electrolysis not excluding. Various types of carbon nanotubes could improve bare graphite electrode properties by different way and so result in obtaining the different records for the same analyte. The automobile catalysts represent mobile sources of palladium. Levels of palladium in environment are continuously increasing and they need to be monitored. Electrochemistry is a useful and inexpensive component of the field of environment monitoring. For Pd(II) electrochemical determination, six types of carbon nanotubes were used as paraffin impregnated graphite electrode (PIGE) surface modifiers. Voltammetric determination brought interesting results of LOD, LOQ, standard and relative precisions of the method. These parameters as well as prediction intervals were calculated according to the technical procedure DIN 32 645 for the six electrodes and three pH values. Modification of PIGE with nitrogen doped carbon nanotubes (LOD = 1.91 × 10−5 mol L−1 or 3.14 × 10−5 mol L−1 for pH 3 and pH 4.5, respectively) seems very promising. In laboratory, functionalized carbon nanotubes, with specific surface area 200 m2 g−1, provided LOD = 1.49 × 10−5 mol L−1 (pH = 3) and 1.42 × 10−5 mol L−1 (pH = 4.5)

Microstructure and mechanical properties of carbon nanotube reinforced cementitious composites developed using a novel dispersion technique

The present paper reports the first attempt of developing carbon nanotube (CNT) reinforced cement composites through a short dispersion route using Pluronic F-127 as a novel dispersing agent. Optimum concentrations of Pluronic for various types of CNT were determined, and the influences of Pluronic and CNT on the microstructure and mechanical properties of cementitious composites were thoroughly investigated. Pluronic with optimized defoamer concentration significantly improved the bulk density and mechanical properties of cement mortar. Further, dispersion of 0.1% single walled nanotube (SWNT) improved flexural modulus of mortar by 72% and flexural and compressive strengths by 7% and 19%, respectively after 28days of hydration. Flexural and compressive strengths with functionalized SWNT increased with the hydration period up to 17% and 23% after 56days, respectively. All CNT reinforced samples exhibited significantly higher stiffness, fracture energy and ductility as compared to plain mortar and composite samples prepared using a common surfactant.

Surface properties of CNTs and their interaction with silica

In order to improve the embedding of carbon nanotubes (CNTs) in cement-based matrices, silica was deposited on the sidewall of CNTs by a sol–gel method. Knowledge of the conditions of CNTs’ surfaces is a key issue in understanding the corresponding interaction mechanisms. In this study various types of CNTs synthesized using acetonitrile, cyclohexane, and methane were investigated with regard to their physicochemical surface properties. Significant differences in surface polarity as well as in the wetting properties of the CNTs, depending on the precursors used, were revealed by combining electro-kinetic potential and contact angle measurements. The hydrophobicity of CNTs decreases by utilising the carbon sources in the following order: cyclohexane, methane, and finally acetonitrile. The XPS analysis, applied to estimate the chemical composition at the CNT surface, showed nitrogen atoms incorporated into the tube structure by using acetonitrile as a carbon source. It was found that the simultaneous presence of nitrogen- and/or oxygen-containing sites with different acid–base properties increased the surface polarity of the CNTs, imparting amphoteric characteristics to them and improving their wetting behaviour. Regarding the silica deposition, strong differences in adsorption capacity of the CNTs were observed. The mechanism of silica adsorption through interfacial bond formation was discussed.

Beyond charge separation: The effect of coupling between titanium dioxide and CNTs on the adsorption and photocatalytic reduction of Cr(VI)

Composite particles comprised of titanium dioxide strongly coupled to various types of carbon nanotubes (CNTs) were prepared by low temperature hydrothermal synthesis.A significant enhancing effect on the photocatalytic reduction rate of Cr(VI) was observed, as a consequence of Cr(VI) adsorption on the CNTs. This rate-enhancing effect was shown to depend on the type of the CNTs and on their functionalization.While evidence for the presence of a synergistic effect is well documented, the comparison between the effects of the various types of CNTs enables to present a new phenomenon., connected to the fact that for this specific model system both reduction and oxidation occur mainly on the CNTs. Here, the extent by which the reduction rate will be enhanced depends not only upon the tendency of the CNTs to adsorb the Cr(VI), but also on the ability of the system to shuttle both holes and electrons to the CNTs, namely whether the CNTs are metallic or not.