Aggregation Of Carbon Nanotubes Research Articles

Biomedical Applications of CNT-Based Fibers.

Carbon nanotubes (CNTs) have been regarded as emerging materials in various applications. However, the range of biomedical applications is limited due to the aggregation and potential toxicity of powder-type CNTs. To overcome these issues, techniques to assemble them into various macroscopic structures, such as one-dimensional fibers, two-dimensional films, and three-dimensional aerogels, have been developed. Among them, carbon nanotube fiber (CNTF) is a one-dimensional aggregate of CNTs, which can be used to solve the potential toxicity problem of individual CNTs. Furthermore, since it has unique properties due to the one-dimensional nature of CNTs, CNTF has beneficial potential for biomedical applications. This review summarizes the biomedical applications using CNTF, such as the detection of biomolecules or signals for biosensors, strain sensors for wearable healthcare devices, and tissue engineering for regenerating human tissues. In addition, by considering the challenges and perspectives of CNTF for biomedical applications, the feasibility of CNTF in biomedical applications is discussed.

CNTs/PVA Composite Aerogel for Efficient Microwave and Acoustic Absorption

The lightweight three-dimensional (3D) carbon nanotubes (CNTs) aerogel has garnered significant interest due to their exceptional characteristics, including high porosity, large specific surface area, and a 3D conductive network. These characteristics make it as a promising candidate for various applications in microwave absorption. However, to construct a multifunctional framework, that can swiftly adapt to complex real-world environments, remains a large challenge. In this study, we fabricated a multifunctional CNTs/polyvinyl alcohol composite aerogel (CPA). Integrating polyvinyl alcohol (PVA) into CNTs aerogel could effectively prevent CNTs aggregation, thus obtaining the remarkable electromagnetic absorption, acoustic, mechanical, and thermal properties. The minimum reflection loss (RL) of CPA achieved an outstanding value of -39.77 dB, measured with a thickness of 2 mm. In addition, CPA showed excellent sound absorption performance, with the highest sound absorption coefficient (SAC) of 0.981. Sound transmission loss (STL) could be improved by adjusting the ratio of CPA, the improvement of STL was 5-8 dB at the mid-high frequencies. Finally, CPA also exhibited excellent thermal insulation performance with the lowest thermal conductivity of 0.0297 W/m·k. The multifunctional capabilities of CPA position it as a highly promising material for various applications, such as microwave absorption, noise reduction, and heat preservation.

Percolation in Carbon Nanotube-Reinforced Polymers for Strain-Sensing Applications: Computational Investigation on Carbon Nanotube Distribution, Curvature, and Aggregation.

The present article investigates the possibility of simulating the electrical conductivity of carbon nanotube-reinforced polymer composites by numerical methods. Periodic representative volume elements are generated by randomly distributing perfectly conductive reinforcements in an insulating matrix and are used to assemble an electrical network representative of the nanocomposite, where the nanotube-nanotube contacts are considered equivalent resistors modeled by means of Simmons' equation. A comparison of the results with experimental data from the literature supports the conclusion that a random distribution of reinforcements is not suitable for simulating this class of materials since percolation thresholds and conductivity trends are different, with experimental percolation taking place before the expectations. Including nanotube curvature does not solve the issue, since it hinders percolation even further. In agreement with experimental observations, the investigation suggests that a suitable approach requires the inclusion of aggregation during the volume element generation to reduce the volume fraction required to reach percolation. Some solutions available in the literature to generate properly representative volume elements are thus listed. Concerning strain sensing, the results suggest that representative volume elements generated with random distributions overestimate the strain sensitivity of the actual composites.

Dual role of pulmonary surfactant corona in modulating carbon nanotube toxicity and benzo[a]pyrene bioaccessibility

Inhaled carbon nanotubes (CNTs) can deposit in the deep lung, where they interact with pulmonary surfactant (PS) to form coronas, potentially altering the fate and toxicity profile of CNTs. However, the presence of other contaminants in combination with CNTs may affect these interactions. Here, we used passive dosing and fluorescence-based techniques confirm the partial solubilization of BaPs adsorbed on CNTs by PS in simulated alveolar fluid. MD simulations were performed to elucidate the competition of interactions between BaPs, CNTs, and PS. We found that PS play two opposing roles in altering the toxicity profile of the CNTs. First, the formation of PS coronas reduce CNTs’ toxicity by decreasing the hydrophobicity of the CNTs and decreasing their aspect ratio. Second, the interaction with PS increases the bioaccessibility of BaP through interactions with PS, which may exacerbate the inhalation toxicity of CNTs. These findings suggest that the inhalation toxicity of PS-modified CNTs should consider the bioaccessibility of coexisting contaminants, with the CNT size and aggregation state playing an important role.

The role of graphene in Graphene-Filled carbon nanotube foam under compression and the corresponding microscopic deformation mechanism

Graphene-filling significantly improves the compressive properties of carbon nanotube (CNT) foam (CF). However, the role of graphene in the graphene-filled CNT foam (GFCF) and the corresponding microscopic deformation mechanism, are still unclear. Here, coarse-grained numerical models of pure CF and GFCF are constructed based on molecular dynamics, and the role of graphene in GFCF and corresponding microscopic deformation mechanisms under compression are investigated. It is found that the compressive modulus of GFCF (5.3 MPa) is much larger than that of pure CF (0.7 MPa). The filling of graphene inhibits the aggregation of CNTs, enhances the dispersion of CNTs, impedes the rearrangement of CNTs, and ultimately improves the compressive modulus of the whole material by improving the bending ability of CNTs. It is further found that the compressive modulus of GFCF can be increased to a maximum of 7.4 MPa as the number of graphene flakes increases to 300, but remains almost the same as the graphene thickness increases. The results in this paper deepen the understanding of the microscopic mechanisms of GFCF and provide scientific guidance for the application of CNT and graphene-based materials.

Encapsulation of Carbon Nanotubes by Styrene and Butyl Acrylate Particles via Suspension Polymerization for Polymerized Toner Applications.

Electrophotographic printing and copying processes primarily use toner, which is a mixture of colorant, polymer, and additives. Toner can be made using traditional mechanical milling techniques or more contemporary chemical polymerization techniques. Suspension polymerization provides spherical particles with less stabilizer adsorption, homogeneous monomers, higher purity, and easier control of the reaction temperature. In contrast to these advantages, however, the particle size resulting from suspension polymerization is too large for toner. To overcome this disadvantage, devices such as high-speed stirrers and homogenizers can be used to reduce the size of the droplets. This research investigated the use of carbon nanotubes (CNTs) instead of carbon black as the pigment in toner development. We succeeded in achieving a good dispersion of four different types of CNT, specifically modified with NH2 and Boron or unmodified with long or short chains in water rather than chloroform, using sodium n-dodecyl sulfate as a stabilizer. We then performed polymerization of the monomers styrene and butyl acrylate in the presence of the different CNT types and found that the best monomer conversion and largest particles (in the micron range) occurred with CNTs modified with boron. The insertion of a charge control agent into the polymerized particles was achieved. Monomer conversion of over 90% was realized with all concentrations of MEP-51, whereas conversion was under 70% with all concentrations of MEC-88. Furthermore, analysis with dynamic light scattering and scanning electron microscopy (SEM) indicated that all polymerized particles were in the micron size range, suggesting that our newly developed toner particles were less harmful and environmentally friendly products than those typically and commercially available. The SEM micrographs clearly showed good dispersion and attachment of the CNTs on the polymerized particles (no CNT aggregation was found), which has never been published before.

Understanding the evolution of mechanical and electrical properties of wet-spun PEDOT:PSS fibers with increasing carbon nanotube loading

Unprecedented demands for advanced fiber materials have been raised by the quick development of wearable intelligent devices. It is still a significant problem to increase the mechanical qualities of fibers without compromising their chemical properties. The impact of different carbon nanotube (CNT) loading on the physical properties of wet-spun poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) fibers are explored in depth along with a wet spinning process for the continuous fabrication of PEDOT:PSS/CNT hybrid fibers. We discovered that the main challenge in a mechanically reinforced system of PEDOT:PSS fibers is to prevent the binding and aggregation of CNT within the fibres; enhancement is typically accomplished at 5 wt% CNT loadings. On the other hand, the conductivity of PEDOT:PSS fibers rises as CNT content increases. By applying the new understanding, the highly conductive PEDOT:PSS/CNT hybrid fiber exhibits greater rate performance and cycle stability in the electrochemical test is obtained. The PEDOT:PSS/CNT hybrid fiber-based fiber-shaped supercapacitors (FSC) have been assembled and they show good long-term cycle stability. Meanwhile, energy and power densities reach ∼16.05 mW h cm−3 and ∼13292 mW cm−3, respectively. This work provides a favorable reference for the mass production of fiber electrodes with high mechanical properties for energy storage.

Manipulating active sites on carbon nanotube materials for highly efficient hydrogen storage

The active sites in porous carbon nanotube (CNT) would determine hydrogen storage performance of CNT. Here, we reported an effective, simple and controllable strategy to improve the hydrogen storage property of function group grafted CNT (fg-CNT). N-CNT-M (La2O3, Ni) would be obtained by the mixture of fg-N-CNT and metallic precursor at calcination of 600 °C. N-CNT-La2O3 has the highest H2 storage capacity of 7.4 wt%, displaying stable hydrogen adsorption/ desorption cycles for more than 20 times at 100 °C and 18 bar. fg-Ni-CNT-PLLA were formed by electrostatic interactions between CN bond of amide and carbonyl of l-polylactic acid (PLLA). fg- Ni-CNT-PLLA also has H2 storage capacity of 6.2 wt% at 100 °C and 18 bar. The experiment found that metal ions or PLLA might be dispersed uniformly in CNT by adjusting the ratio of grafted hydroxyl (OH) to acylamino (–CONH2). N-CNT-La2O3 has better hydrogen storage performance than fg-CNT-PLLA because the aggregation of CNT would be caused by the molecular movement of PLLA during hydrogenation and dehydrogenation. This work provides guidance for the development of efficient hydrogen storage materials.

Incorporating Graphene Nanoplatelets and Carbon Nanotubes in Biobased Poly(ethylene 2,5-furandicarboxylate): Fillers' Effect on the Matrix's Structure and Lifetime.

Poly(ethylene 2,5-furandicarboxylate) (PEF) nanocomposites reinforced with Graphene nanoplatelets (GNPs) and Carbon nanotubes (CNTs) were in situ synthesized in this work. PEF is a biobased polyester with physical properties and is the sustainable counterpart of Polyethylene Terephthalate (PET). Its low crystallizability affects the processing of the material, limiting its use to packaging, films, and textile applications. The crystallization promotion and the reinforcement of PEF can lead to broadening its potential applications. Therefore, PEF nanocomposites reinforced with various loadings of GNPs, CNTs, and hybrids containing both fillers were prepared, and the effect of each filler on their structural characteristics was investigated by X-ray Diffraction (XRD), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), and X-Ray Photoelectron Spectroscopy (XPS). The morphology and structural properties of a hybrid PEF nanocomposite were evaluated by Transmission Electron Microscopy (TEM). The thermo-oxidative degradation, as well as lifetime predictions of PEF nanocomposites, in an ambient atmosphere, were studied using Thermogravimetric Analysis (TGA). Results showed that the fillers' incorporation in the PEF matrix induced changes in the lamellar thickness and increased crystallinity up to 27%. TEM analysis indicated the formation of large CNTs aggregates in the case of the hybrid PEF nanocomposite as a result of the ultrasonication process. Finally, the presence of CNTs caused the retardation of PEF's carbonization process. This led to a slightly longer lifetime under isothermal conditions at higher temperatures, while at ambient temperature the PEF nanocomposites' lifetime is shorter, compared to neat PEF.

Construction of unique conductive networks in carbon nanotubes/polymer composites via poly(ε-caprolactone) inducing partial aggregation of carbon nanotubes for microwave shielding enhancement

• Unique conductive networks of individual CNTs and CNT clusters are constructed. • Poly(ε-caprolactone) inducing partial aggregation of CNTs creates CNT clusters. • The unique conductive networks show high conductivity and microwave SE. • Balance amounts for CNTs and PCL exist for the unique conductive networks. • Polymer pairs are important to form the unique conductive networks. Herein, a unique conductive network, which includes individual carbon nanotubes (CNT) and some CNT clusters (CNT/CNT-cluster) formed via poly(ε-caprolactone) (PCL) inducing partial aggregation of CNTs, is constructed in CNTs filled CPCs. Three different kinds of polymers, which are isotactic polypropylene (PP), polystyrene (PS) and polylactic acid (PLA), are used to evaluate the effect of polymer matrix on the unique conductive network. A comparative study on the electrical conductivity and microwave shielding properties are also carried in these composites. The effect of CNTs and PCL loadings on the formation of CNT-clusters in the samples is also discussed in this study. Due to PCL inducing partial aggregation of CNTs and the good distribution of residue CNTs in PLA, the excellent CNT/CNT-cluster conductive network is formed in the CNT/PCL/PLA composites. Comparing with the traditional conductive network, the CNT/CNT-cluster conductive network exhibits high efficiency for improving electrical conductivity and microwave shielding property.

Self‐Sensing Cementitious Composites with Hierarchical Carbon Fiber‐Carbon Nanotube Composite Fillers for Crack Development Monitoring of a Maglev Girder

In view of high-performance, multifunctional, and low-carbon development of infrastructures, there is a growing demand for smart engineering materials, making infrastructures intelligent. This paper reports a new-generation self-sensing cementitious composite (SSCC) incorporated with a hierarchically structured carbon fiber (CF)-carbon nanotube (CNT) composite filler (CF-CNT), which is in situ synthesized by directly growing CNT on CF. Various important factors including catalyst, temperature, and gas composition are considered to investigate their kinetic and thermodynamic influence on CF-CNT synthesis. The reciprocal architecture of CF-CNT not only alleviates the CNT aggregation, but also significantly improves the interfacial bonding between CF-CNT and matrix. Due to the synergic and spatially morphological effects of CF-CNT, that is, the formation of widely distributed multiscale reinforcement networks, SSCCs with CF-CNTs exhibit high mechanical properties and electrical conductivity as well as excellent self-sensing performances, particularly enhanced sensing repeatability. Moreover, the SSCCs with CF-CNTs are integrated into a full-scale maglev girder to devise a smart system for crack development monitoring. The system demonstrates high sensitivity and fidelity to capture the initiation of cracks/damage, as well as progressive and sudden damage events until the complete failure of the maglev girder, indicating its considerable potential for structural health monitoring of infrastructures.

The aggregation of carbon nanotubes deteriorates their adverse effects on pulmonary surfactant monolayer

The wide use of carbon nanotubes (CNTs) increases the concern of their potential risks upon human exposure, especially through respiratory tract. The small size of CNTs allows them to deposit into the deep lung where they inevitably interact with pulmonary surfactant (PS) monolayer and thus could profoundly influence the biophysical function of PS monolayer. Using coarse-grained molecular dynamics simulations, we studied how the aggregation state of CNTs regulated the interactions of different sized CNTs with the PS monolayer at the air-water interface. Compared with the dispersed CNTs, the aggregated CNTs induced more severe structure disturbance of the PS monolayer at both compression and expansion stages. The increased diameter, initial attack angle, and configuration irregularity of the aggregated CNTs enhanced the lipid disturbance around the CNTs and promoted the pore formation on the PS monolayer under a high surface tension. As a result, the aggregated CNTs tended to inhibit the biophysical function of the PS monolayer and were more difficult to be cleared from the monolayer than the dispersed CNTs. Our results suggest that the aggregated CNTs, rather than the dispersed ones, should be given more weight in assessing the pneumonic nanotoxicity caused by the inhaled CNTs.

Investigation of the interphase structure in polyamide 6–matrix, multi-scale composites

In this study, we investigated the dispersion of carbon nanotubes and the interphases formed around them in nanocomposites with a polyamide 6 matrix (with carbon nanotube reinforcement) and hybrid composites with the same matrix, reinforced with carbon nanotubes and carbon fibers. Small-angle neutron scattering (SANS) experiments showed that carbon fibers effectively increased the dispersion of the carbon nanotubes. The average size of the carbon nanotube aggregates were significantly smaller, but the reinforcement–matrix interface area was larger in the hybrid composites than in the nanocomposites. Nanotube dispersion had a significant effect on the crystalline structure; the X-ray diffraction patterns showed that in the hybrid composites, the crystallites grew epitaxially on the surface of the well-dispersed carbon nanotubes, which resulted in decreased average crystallite size. In the hybrid composites, the smaller crystallites inferred a larger rigid amorphous fraction in the matrix. The larger interphase fraction in the hybrid composites also led to better mechanical performance.

Molecular Alignment of a Meta-Aramid on Carbon Nanotubes by In Situ Interfacial Polymerization.

Molecularly organized nanocomposites of polymers and carbon nanotubes (CNTs) have great promise as high-performance materials; in particular, conformal deposition of polymers can control interfacial properties for mechanical load transfer, electrical or thermal transport, or electro/chemical transduction. However, controllability of polymer-CNT interaction remains a challenge with common processing methods that combine CNTs and polymers in melt or in solution, often leading to nonuniform polymer distribution and CNT aggregation. Here, we demonstrate CNTs within net-shape sheets can be controllably coated with a conformal coating of meta-aramid by simultaneous capillary infiltration and interfacial polymerization. We determine that π-interaction between the polymer and CNTs results in chain alignment parallel to the CNT outer wall. Subsequent nucleation and growth of the precipitated aramid forms a smooth continuous layered sheath around the CNTs. These findings motivate future investigation of mechanical properties of the resulting composites, and adaptation of the in situ polymerization method to other substrates.

The creep behavior of semicrystalline carbon nanotube/polypropylene nanocomposite: A coarse-grained molecular study

Polypropylene (PP) is vulnerable to creep under constant loads, which is a serious problem for PP-based applications. By incorporating carbon nanotubes (CNTs), the CNT/PP composite exhibits improved creep resistance, while the CNT aggregation with high contents could limit the improvement. In order to ensure the long-term durability, the creep response of CNT/PP composite with different CNT contents should be carefully characterized. In this paper, the coarse-grained models of CNT/PP nanocomposite with various CNT contents are constructed, which are subjected to constant loads at various levels. It is found that the threshold stress and energy barrier for the initiation of fracture show an initial increase and a subsequent decrease, with the transition at 3 wt%. The decline of creep properties with high CNT contents is related to the limited CNT restriction effect on the PP chain behaviors, which is resulted from the sliding between CNT chains and the accelerated interfacial sliding between CNT and PP due to increased interfacial voids, as observed from the behaviors and interactions of investigated molecules and chains during creep. This study provides insights into the molecular creep behavior of CNT/PP nanocomposite, which contributes to the understanding of degradation of composite materials under constant loads.

Effects of carbon nanotube dosage and aggregate size distribution on mechanical property and microstructure of cemented rockfill

The mechanical and structural properties of cemented rockfill produced by mineral wastes as recycled aggregates limit its application. In this paper, the macroscopic mechanical and microscopic scanning tests were carried out to study the mechanical property and microstructure of cemented rockfill reinforced by carbon nanotubes (CNTs) and fractal aggregates. The strengthening and deterioration mechanisms of CNT dosage on cemented rockfill were revealed for systematically evaluating its engineering availability. The influencing mechanism of aggregate size distribution on cemented rockfill was clarified to analyze the contribution of optimizing aggregate size distribution. The results show that the strengthening of cemented rockfill by appropriate CNTs includes bridging microcracks, compacting micropores and reinforcing cemented matrix, while the deterioration by excessive CNTs is attributed to form the agglomerative clusters and hollow cemented matrices. The cemented rockfill with superior aggregate size distribution has uniform and dense microstructure with relatively few defects, which is conducive to CNT reinforcement.

Copper sulfide nanoribbon growth triggered by carbon nanotube aggregation via dialysis.

The growth of copper sulfide (Cu x S) nanoribbons, a class of Cu x S nanomaterials, was achieved by the aggregation of single-walled carbon nanotubes (SWCNTs) via a dialysis process. The obtained nanoribbon structure and its constituent elements on a film of SWCNT aggregates were confirmed by transmission electron microscopy (TEM) and scanning transmittance electron microscopy-energy dispersive X-ray spectroscopy. The subsequently obtained TEM images and Raman spectra revealed that nucleus synthesis and subsequent growth of Cu x S nanoribbons occurred during the aggregation of SWCNTs. The growth procedure described in this work provides an approach for the wet chemical synthesis of metal sulfide nanomaterials.

THE INFLUENCE OF POLYETHYLENE GLYCOL MODIFIERS ON THE DISTRIBUTION OF CARBON NANOTUBES IN THE POLYMER MATRIX

In polymer nanocomposites filled with carbon nanotubes (CNTs), it is very difficult to ensure the uniformity of the distribution of nanotubes in the polymer matrix, as well as the stability of this dispersion over time. Therefore, in such systems, over time, due to the strong van der Waals forces of attraction between individual nanotubes, the aggregation of filler particles takes place, which leads to the transition from the nano to the micro level of their structural organization. Such a transition negatively affects the set of functional properties of polymer nanocomposites filled with CNTs. Therefore, the development of new approaches to the stabilization of nanoparticles in order to prevent their aggregation for the creation of nanocomposite materials with improved functional characteristics is an urgent task. The paper studied the effect of non-covalent modification of carbon nanotubes using polyethylene glycol (PEG) of different molecular weight on the degree of their distribution in the polymer matrix. The peculiarities of the distribution of CNTs of various types: unmodified and non-covalently modified, using different molecules of PEG, nanotubes were studied. From the analysis of microscopic images, it was found that modified CNTs are more evenly distributed in the polymer matrix than unmodified nanotubes, which can be explained by the different nature of the interaction between the polymer matrix and CNTs. It was determined that for systems containing modified CNTs, a higher value of the fractal dimension is observed, which indicates the formation of looser CNT aggregates, while unmodified CNTs show a tendency to form denser aggregates. It was found that the value of the fractal dimension for functionalized CNTs is close to 3, which indicates a uniform distribution of CNTs. It was established that the modifier based on PEG-10000 exerts the highest stabilizing effect. At the same time, CNTs are most evenly distributed throughout the volume of the material.

Dual functions of three-dimensional hierarchical architecture on improving the rate capability and cycle performance of LiNi0.8Co0.1Mn0.1O2 cathode material for lithium-ion battery

The main obstacles in lithium-ion battery are limited by rate performance and the rapid capacity fading of LiNi0.8Co0.1Mn0.1O2 (NCM811). Herein, a novel three-dimensional (3D) hierarchical coating material has been fabricated by in situ growing carbon nanotubes (CNTs) on the surfaces of Ni–Al double oxide (Ni–Al-LDO) sheets (named as LDO&CNT) with Ni–Al double hydroxide (Ni–Al-LDH) as both the substrate and catalyst precursor. The resultant LDO&CNT nanocomposites are uniformly coated on the surfaces of NCM811 by the physical mixing method. The rate capability of the resultant cathode material retains to 78.80% at a current rate of 3C. Its capacity retention increases by 6.7–14.42% compared with pristine NCM811 after 100 cycles within a potential range of 2.75–4.3 V at 0.5C. The improved rate capability and cycle performance of NCM811 are assigned to the synergistic effects between Ni–Al-LDO and CNTs. The hierarchical LDO&CNT nanocomposites coating on the surface of NCM811 avoids the aggregation of conductive CNTs and the stacking of Ni–Al-LDO nanosheets. Furthermore, it accelerates Li+ and electrons shuttle and reduces the reaction of Li2O with H2O and CO2 in air, which results in Li2CO3 and LiOH alkali formation on the NCM811 surface.

Light-induced thermal convection for collection and removal of carbon nanotubes

Carbon nanotubes (CNTs) have exhibited immense potential for applications in biology and medicine, and once their intended purpose is fulfilled, the elimination of residual CNTs is essential to avoid negative effects. In this study, we demonstrated the effective collection and simple removal of CNTs dispersed in a suspension via thermal convection. First, a tapered fiber tip with a cone angle and end diameter of 10° and 3 μm, respectively, was fabricated via a heating and pulling method. Further, a laser beam with a power and wavelength of 100 mW and 1.55 μm, respectively, was launched into the tapered fiber tip, which was placed in a CNT suspension, resulting in the formation of a microbubble on the fiber tip. The temperature gradient on the microbubble and suspension surface induced thermal convection in the suspension, which resulted in the accumulation of CNTs on the fiber tip. The experimentally formed CNT cluster possessed a circular top surface with a diameter of 87 μm and an arched cross-section with a height of 19 μm. Furthermore, this CNT cluster was firmly attached to the fiber tip. Therefore, the removal of CNT clusters can be realized by simply removing the fiber tip from the suspension. Moreover, we simulated the thermal convection that caused CNT aggregation. The obtained results indicate that convection near the fiber tip flows toward it, which pushes the CNTs toward the fiber tip and enables their attachment to it. Further, the flow velocity is symmetrically distributed as a Gaussian function, which results in the formation of a circular top surface and arched cross-sectional profile for the CNT cluster. Our method may be applied in biomedicine for the collection and removal of nano-drug residues.