Aggregation Of Carbon Nanotubes Research Articles

Ionic liquid functionalized 3D graphene-carbon nanotubes‒AuPd nanoparticles‒molecularly imprinted copolymer based paracetamol electrochemical sensor: Preparation, characterization and application

An innovative electrochemical sensor for paracetamol (PCM) determination was fabricated by electropolymerization imprinting on three-dimension (3D) AuPd nanoparticles‒ionic liquid (IL) functionalized graphene‒carbon nanotubes nanocomposite (AuPd/GN-CNTs-IL) modified glassy carbon electrode. The GN-CNTs supported AuPd alloy nanoparticles were prepared via one-pot hydrothermal method in the presence of IL (i.e. 1-hydroxyethyl-3-methyl imidazolium bis[(trifluoromethyl) sulfonyl] imide), which not only promoted the formation of small AuPd alloy nanoparticles, but also acted as “spacer” to prevent the π-π stacking and aggregation of graphene sheets and carbon nanotubes. The resulting composite had large surface area and high electrocatalysis. The PCM imprinted poly(carbazole-co-pyrrole) exhibited good recognition to PCM and had high stability. Based on the synergic effect of PCM imprinted copolymer and 3D AuPd/GN-CNTs-IL nanocomposite, a highly selective and sensitive electrochemical sensor was established. It presented a good linear relationship from 0.10 to 10 μM with a low limit of detection of 50 nM (S/N = 3). The sensor could be applied to the detection of PCM in biological samples, with acceptable recoveries (84.5%–102%). In addition, it was successfully used to monitor the concentration of PCM in urine from a patient with fever cold.

Carbon nanotube arrays hybrid membrane with excellent separation performance and conductivity

Hybrid materials based on carbon nanotubes (CNTs) and polymers have shown attractive properties and potential applications. However, the poor quality and aggregation of CNTs are challenging during the preparation of hybrid materials. To address these issues, we fabricated the vertically aligned (VA) CNT (open-end) hybrid membrane with annealing treatment, which significantly improves the phenol separation performance, single gas permeability of CO2 and N2, and binary CO2/N2 mixture separation performance. The free volume provided by the orderly CNT channels and their atomically smooth walls contribute to the markedly increased diffusion rate and permeability of the membrane. The density functional theory (DFT) calculations indicate that the small molecules in the membrane preferentially transport along the internal channels of CNTs. Furthermore, this membrane also has excellent conductivity and resistance stability after 50 cycles of tensile deformation. For the first time, it reveals that this unique structured CNTs membrane can be applied in environmental, gas separation, and electronics fields with superior performance.

Biocompatibility studies of macroscopic fibers made from carbon nanotubes: Implications for carbon nanotube macrostructures in biomedical applications

Macroscopic carbon nanotube fiber (CNTF) is a continuous monofilament microns-thick thread whose cross section consists of ten to hundreds of millions of tightly packed, aligned carbon nanotubes (CNTs). CNTF is flexible, strong, conductive, and has excellent electrochemical properties, making it an ideal candidate for bioelectronic interfaces. CNTF recent applications range from neuroelectronics and cardiac electrophysiology to biosensors. However, various reports on CNT toxicity have generated confusion on the biosafety of all CNT-based materials despite significant differences among individualized CNTs, unstructured CNT aggregates, and stable CNT macrostructures in compositions and morphologies. Here, the bio- and immune-compatibility profiles of CNTF are systematically evaluated at cellular, organ, and systemic levels. In vitro, CNTF shows good cytocompatibility with cell-lines like HEK-293, SH-SY5Y, as well as primary cardiomyocytes and macrophages. Ex vivo, CNTF shows no impact on blood parameters or functionality of key immune cells. In vivo, intraperitoneal injections of leachates from CNTF production reveal no evidence of toxicity suggesting no leachable or residual degradable byproducts. In addition, as the first multiscale toxicological evaluation of a CNT macrostructure, this report demonstrates that CNT macrostructures should be evaluated as their standalone class of carbon material, separately from individualized CNTs and unstructured CNT agglomerates.

Characterization of Molecular Spacer-Functionalized Nanostructured Carbons for Electrical Energy Storage Supercapacitor Materials

The use of molecular spacers between Carbon Nanotubes (CNTs) has been shown to increase the ion-accessible surface area for use in supercapacitor materials. Maintaining porosity and electrical conductivity is important for maximizing capacitance, energy storage, and power. Two reported novel coordination complexes have shown exceptional Faradaic charge transfer and binding capabilities to prevent CNT aggregation. Dispersion stability measurements show less aggregation of HiPco Single Walled CNTs (SWCNTs) compared to other chirality and multilayered nanotubes. Cu2FcOH binds weakly to CNTs compared +2Zn2 and +2Ru2 due to Columbic electrostatic interactions, which is favorable because it does not collapse the electrical double layer as strongly as +2Zn2 or +2Ru2. Adsorption isotherms and a full characterization (1H NMR, ATR FT-IR, UV-Vis, CV) of these novel complexes are presented. Electrical characterization using CV, charge discharge, and electrochemical impedance spectroscopy and the supercapacitor performance of functionalized thin film electrodes are presented as a function of spacer properties and nanostructured carbon tube diameter. This study uses rigid, earth-abundant coordination complexes that bind to and intercalate between SWCNTs. These functionalized nanostructured carbons are then used to make electrodes for electrical double layer supercapacitors. A complete description of the synthesis, characterization, and processing of these materials is described.

In Situ Interfacial Polymerization: A Technique for Rapid Formation of Highly Loaded Carbon Nanotube‐Polymer Composites

AbstractComposites of polymers and organized carbon nanotube (CNT) networks have been proposed as next‐generation lightweight structural materials, yet polymer infiltration of CNT networks often results in stress‐concentrating heterogeneities, due to local CNT aggregation or incomplete infiltration. Herein, it is demonstrated that dense CNT‐polymer composites with tailored polymer distribution can be obtained by interfacial polymerization (IP), performed in situ within CNT networks. Three regimes of the in situ interfacial polymerization (ISIP) process are identified: a reaction‐limited regime where the polymer forms beads on the CNTs; a uniformly‐filled regime with polymer throughout the CNT network; and a transport‐limited regime with polymer only near the outer surface of the network. Uniform polyamide‐CNT composite sheets obtained by this method have a Young's modulus of 31 GPa and a tensile strength of 776 MPa, which is a two‐fold increase compared to the pristine CNT sheets. Premature failure of the composites is attributed to large voids in the pristine CNT sheets, suggesting that further improved mechanical properties can be achieved with a more homogeneous CNT network. Nevertheless, the rapid rate and overall controllability of ISIP suggest its viability for formation of polymers within CNT networks via roll‐to‐roll methods.

Free arc liquid-phase dispersion method for the preparation of carbon nanotube dispersion

In this study, a new method of rapid preparation of carbon nanotube (CNT) solution with highly dispersed morphology by free arc excitation is proposed, which shortens the time of the preparation of CNT solution with low concentration. The principle is that the high-energy flow density heat generated by the free arc makes the vaporizable substance coated on the surface of CNTs vaporize rapidly, and then generates the bulk increasing motion, which makes the CNTs aggregates dispersed, and finally forms the CNTs gas-phase dispersion monomer with high dispersion or the cross-linking morphology of few CNTs. In this paper, the influence of gum Arabic (GA) and deionized water (DI water) contents in CNTs mixed electrode on the dispersion of CNTs in different environments (gas phase and liquid phase) is explored. In the limited case of this work, the dispersion effect is better when the mass ratio of CNTs, GA and DI water is 1:0.04:3.96 in the liquid-phase environment. The preparation method reported in this work is expected to be a rapid way to obtain low-concentration nanodispersion.

Enhancement of the Mechanical Properties of PAN Nanofiber/Carbon Nanotube Composite Mats Produced via Needleless Electrospinning System

The current research presents the optimization of the parameters involved in the production of polyacrylonitrile (PAN) nanofibers via the needleless electrospinning system. The experiments were designed using the Taguchi method to investigate the morphological, physical, and mechanical properties of the nanofibers. The single-wall carbon nanotubes (CNT) were used in order to improve the mechanical properties of the electrospun nanofibers. The diameter of the PAN nanofibers in the needleless system was less than 300 nm, which was smaller than that in the conventional system. The results showed that the concentration had the greatest impact on the fiber diameter than other parameters in both PAN and PAN/CNT nanofibers. The specific stress of the nanofibers produced by the needleless electrospinning system was lower than that created by the conventional electrospinning system. Addition of The CNT caused to improve the specific stress of the PAN/CNT nanofibers compared with the PAN nanofibers. However, excessive amounts of CNT had a negative effect on the elongation and modulus because of the aggregation of CNT inside the nanofibers. The X-ray diffraction analysis was used to study the crystalline behavior of the PAN nanofibers produced via the needleless electrospinning system. The results showed that the PAN nanofibers had amorphous structure compared with the conventional PAN nanofibers.

The effects of pulverization treatment for the mechanical properties of polyamide 6 fiber filled with carbon nanotubes

An advanced and latest method for pulverizing the aggregates of carbon nanotubes (CNTs) by wet-jet milling process has been adopted for reinforcement of polyamide 6 (PA6) fibers. Unpulverized and pulverized CNTs were added to PA6 fibers by using general type kneading and spinning apparatus. Although the tensile modulus of PA6 fibers 6% increased by adding CNTs, regardless of the pulverization treatment, the tensile strength 10% increased only by adding pulverized CNTs. The improvements in the mechanical properties were attributed to the mechanical properties of CNTs themselves because CNTs have little effect on the crystallization and interaction with polymer chains of PA6. On the other hand, the aggregates were observed in PA6 fibers with unpulverized CNTs while CNTs were highly dispersed in PA6 fibers with pulverized CNTs. Therefore, it is revealed that the pulverization of CNTs is a significant factor for improving tensile strength of PA6 fibers. Applying pulverization technique to PA6 fibers aids a feasibility of wide range of applications such as tennis racket strings.

Physical and mechanical properties of polymer nanocomposites of penton - carbon nanotubes system

The work is dedicated to the solution of an important task - the creation and study of new polymer compositions, which, unlike traditional polymeric materials, are characterized by polyfunctionality and high performance characteristics.Over the past few decades, among nanofillers, considerable attention has been paid to carbon nanotubes (CNTs) due to their special mechanical and thermal properties, geometric parameters, low mass density and their inherent electrical properties. As a polymer matrix for studying systems with an active interaction of components, it is proposed to use polymers that are capable of crystallization and include polar groups. A typical representative of such polymers is the high molecular weight polyester - penton. Such composite systems are favorably distinguished by the presence of two phase instabilities in the temperature range under study, namely, the melting of the crystalline phase and the glass transition of the amorphous component of the polymer matrix, which will provide more complete and deeper information about the mutual influence of the components of such systems. The ultrasonic method has been used for experimental study of the acoustic properties and structure of polymer nanocomposites of the penton - carbon nanotubes system. An analysis of the studied concentration dependences of the characteristics at frequencies of 5, 7.5, and 10 MHz indicates a strong character of the interaction between the penton - CNT system components. The research results indicate that the ultrasound velocity in filled systems in the entire studied concentration region is significantly higher than for an unfilled penton, and for thecarbon nanotubesfilled penton, a significant increase in the elasticity of the composite compared with an unfilled polymer matrix takes place. Obviously, this can occur due to a significant change in the structure of the polymer component of the system and the formation of an interfacial layer around the CNT with a more ordered structure respectively to pure penton. Additional information is provided by the dependences of the “jump” of the absorption coefficient on the frequency and the dependences of the tangent of the angle of mechanical losses (tgδ), which indicate that the size of carbon nanotube aggregates in the penton matrix as an obstacle to a mechanical wave is much smaller than the size of the penton particles, and the constancy of all studied characteristics when the concentration of CNTs φ ≈ 0.3 vol. % indicates the transition of the penton at this concentration to the state of the wall layer.

A semi-empirical model for thermal conductivity of polymer nanocomposites containing carbon nanotubes

A new version of the semi-empirical Halpin–Tsai (H–T) model is presented to evaluate the effective thermal conductivity of general carbon nanotubes (CNTs)-reinforced polymer nanocomposites. The model captures the influences of the CNTs alignment, random orientation, aggregation, waviness, length, diameter and the CNT/polymer interfacial thermal resistance parameters. In order to verify the suitability of the new H–T model, the numerically calculated thermal conductivities are compared with existing experimentally measured ones. An excellent predictability is found of the modified H–T model over a wide range of the tests. The consideration of the CNT waviness and the interfacial thermal resistance parameters is seriously essential for a more realistic prediction in all conditions. For aligned CNT-reinforced polymer nanocomposites, considering the alignment factor seems to be very important. Moreover, in the case of well-dispersed CNTs into the matrix, it is necessary to incorporate the CNT random orientation parameter. Additionally, when CNTs are not well dispersed, the CNT aggregation and random orientation parameters must be incorporated in the analysis. The effects of the CNT volume fraction, length, diameter and non-straight shape on the nanocomposite thermal conducting behavior are estimated in details. The results clearly expose that it is needed to eliminate the aggregation, use the straight CNTs and form a strong interface if the full potential of CNT reinforcement is to be realized. Finally, the thermal conductivities of CNT-shape-memory polymer nanocomposites at different temperatures are obtained.

Difference in the interaction of nano-diameter rod and tubular particles with a disclination line in a nematic liquid crystal.

In the presence of a disclination line, inclusions within an aligned nematic liquid crystal (LC) are first attracted and ultimately trapped in it. The kind of orientational distortion created by the inclusions is fundamental in determining the trapping. In the present work, we observe differences in the trapping behaviour, onto a ½ defect line in a nematic LC, of two types of particles both elongated but different in their actual geometry. Even if both types have cylindrical shape, aggregates of Mo6S2I8 nanowires (rod-like shape) and multiwall carbon nanotubes (tubular shape, i.e. hollow) trap differently although still due to deformations induced in the LC director field. Attractive forces are stronger on elongated bundles of nanowires than on similarly sized bundles of multi-wall carbon nanotubes. The reason is the difference in the attraction forces originating from different types of distortions of the LCs. The hollow and the full cylinders are not homotopically equivalent and this inequivalence holds also for the liquid crystal around them. The nanowires induce defects in the LC close-by their surfaces as shown for microrods, topologically equivalent to spheres. In contrast, multi-wall carbon nanotubes, being hollow, do not form defects close to their ends. However, the tubes are strongly bent and the strong planar anchoring of LC at the surface induces deformation in the LC enabling attraction forces with the defect line. HiPco single wall carbon nanotubes could not be trapped because their bundles looked much straighter and smaller than the ones of MWCNTs and thus neither defects nor standard strong deformations are expected. In conclusion, even if the shape of both types of particles is cylindrical, the topological difference between rods and tubes has profound consequences on the physical behaviour and on the presence and type of defect-mediated nematic attraction forces.

RELATIONSHIP BETWEEN THE APPLIED STRESS TRANSFER AND THE NANOFILLER AGGREGATION LEVEL FOR POLYMER/ CARBON NANOTUBES NANOCOMPOSITES

The relationship was studied between the parameter important for the formation of the properties of polymer nanocomposites, namely, the transfer efficiency of the mechanical stress applied to the sample from the polymer matrix to the nanofiller, and the structure of carbon nanotubes formed in this matrix. It has been found that the indicated efficiency, controlled by the level of interfacial adhesion of the nanofiller-polymer matrix, critically depends on the main negative process for all nanocomposites, that is, aggregation of the nanofiller, an increase in the degree which reduces the efficiency of stress transfer. For the nanocomposites under consideration, the process of carbon nanotubes aggregation takes place in the form of emergence of their annular formations that are fractal objects, which has been confirmed experimentally. This fact allows characterization of the carbon nanotubes structure in a polymer matrix using a fractal dimensionality. It has been found that an increase in the fractal dimensionality of the annular formations of carbon nanotubes, reflecting an upgrowth in the degree of their aggregation unambiguously reduces the efficiency of mechanical stress transfer as well as the nanofiller ability to generate interfacial regions.

Bubble-propelled micromotors based on hierarchical MnO2 wrapped carbon nanotube aggregates for dynamic removal of pollutants.

Water pollution is currently an urgent public health and environmental issue. Bubble-propelled micromotors might offer an effective approach for dealing with environmental contamination. Herein, we present the synthesis of multi-walled carbon nanotube (MWCNT)/manganese dioxide (MnO2) micromotors based on MWCNT aggregates as microscale templates by a simple one-step hydrothermal procedure. The morphology, composition, and structure of the obtained MWCNT/MnO2 micromotors were characterized in detail. The MnO2 nanoflakes formed a catalytic layer on the MWCNT backbone, which promoted effective bubble evolution and propulsion at remarkable speeds of 359.31 μm s−1. The bubble velocity could be modulated based on the loading of MnO2 nanoflakes. The rapid movement of these MWCNT/MnO2 catalytic micromotors resulted in a highly efficient moving adsorption platform, which considerably enhanced the effectiveness of water purification. Dynamic adsorption of organic dyes by the micromotors increased the degradation rate to approximately 4.8 times as high as that of their corresponding static counterparts. The adsorption isotherms and adsorption kinetics were also explored. The adsorption mechanism was well fitted by the Langmuir model, following pseudo-second-order kinetics. Thus, chemisorption of Congo red at the heterogeneous MnO2 wrapped microimotor surface was the rate determining step. The high propulsion speed and remarkable decontamination efficiency of the MWCNT/MnO2 micromotors indicate potential for environmental contamination applications.

Effect of Air Oxidation Treatment of CNT on Tensile Strength of CNT / Polyamide 6 Nanofibres and their Dispersion

Carbon nanotube (CNT) is excellent in mechanical and thermal characteristics, and are expected to be used in various fields such as nanoelectronic devices and reinforcing nanofillers for composites. It is expected that mechanical properties can be improved by adding CNT into the polymer. However, since CNT exists in a state of aggregation due to van der Waals forces, it is necessary to uniformly disperse CNT in order to fully extract the properties of CNT. In this study, CNT/polyamide 6 (PA6) composite nanofibres were fabricated by the electrospinning method. In order to disperse CNT in the CNT/PA6 nanofibres, CNT were subjected to air oxidation treatment. As a result of evaluating the dispersibility of CNT by sedimentation test, the dispersibility in pure water and HFIP is improved by oxidizing the surface of CNT. By conducting tensile tests and SEM observation of the nanofibre non-woven fabric, the influence of the surface treatment on the tensile strength of CNT/PA6 nanofibres and the dispersion of CNT was clarified. Although the addition of untreated CNT to PA6 nanofibres reduces the displacement at break, air oxidized CNT/PA6 suppressed the formation of CNT aggregates, and showed higher tensile strength and larger displacement at break than untreated CNT/PA6.

Improvement of electrical conductivity of PEMA film by incorporating EMITFSI and carbon based nanofiller

Abstract The electrical conductivity of dual inclusion of 1-ethyl-3-methyl imidazolium bis(trifluorosulfonyl) imide ionic liquid and three allotropes of carbon based nanofillers (multiwalled carbon nanotube, graphene and graphite) in poly (ethyl methacrylate) films with thickness ranging from 100 to 250 μm has been investigated in the temperature range of 300–380 K. It is found that the electrical conductivity of film with 0.5 wt % multiwalled carbon nanotube has the highest ambient electrical conductivity of 4.9 × 10−6 Scm−1 which is five order of magnitude higher than pure poly (ethyl methacrylate) film. Moreover, the stability of the highest electrical conductivity is also found to be significantly improved for a longer period. From the investigated physicochemical properties, these improvements are likely can be explained by the aggregation of multiwalled carbon nanotubes, the increase in electronic transport and the reduction in glass transition temperature which likely effect its ionic mobility. Consequently, these enhancements may lead to a promising improvement of its electrical properties for a stable near room temperature application.

The stability, viscosity and thermal conductivity of carbon nanotubes nanofluids with high particle concentration: A surface modification approach

This study demonstrated a novel approach to formulating nanofluids with high mass concentration, good colloidal stability, enhanced thermal conductivity and moderate viscosity increase from the β-Cyclodextrin (β-CD) modified carbon nanotubes. This method could be applied to a variety of functional nanomaterials and make use of the liquid properties and functions of dispersed nanoparticles to make nanofluids become more efficient heat transfer fluids and industrial application media. A scalable improved two-step method based on mechanical milling technique for the preparation of nanofluids was demonstrated. Highly stable nanofluids with up to 5 wt% of surface-modified multiwalled carbon nanotubes (CD-CNTs) in deionized water were successfully obtained. It was demonstrated that the preparation method could effectively disperse the carbon nanotube aggregates, providing relatively small increases in viscosity (the viscosity of 5 wt% nanofluids was 31 mPa·s averagely). The thermal values of CD-CNTs/water nanofluids reached to their maximum values (1.013 W/(m·K) and 69.68%, respectively) at 5 wt%. Heat was more easily transferred along the carbon nanotubes, which was more efficient than thermal conduction through solid-liquid-solid paths. This study has demonstrated that the proposed surface modification technique and preparation method could together ensure the requirements for achieving MWCNTs nanofluids with high mass concentration and desired properties.

Thermoelectric Effect of Buckypaper/Copper Assembly

Carbon nanotubes (CNTs) exhibit excellent electrical and thermal properties that have been used in several device assemblies, such as electrode sheets made from an aggregate of CNTs, also called as buckypaper (BP). Despite that, the properties of single CNTs are reduced when randomly assembled to form a BP. In this way, this study investigated the thermoelectric effect of a BP electrode assembled on a copper electrode with an active area of 4.0 cm2. The micrographs were obtained by scanning electron microscopy and show morphology agglomerated of multiwalled CNTs, which permeated into the filter paper, forming a thickness of 67.33 μm. Moreover, indoor/outdoor tests were performed approaching the BP electrode from a heat source. Thus, the electrical responses in function of temperature variation show maximum thermovoltages of 9.0 mV and 40.73 mV from indoor and outdoor tests, respectively. Finally, an average Seebeck coefficient for the BP/copper electrodes array of 35.34 ± 6.0 mV/K was estimated from 298 to 304 K. These findings suggest that this assembly will be easily applied in thermoelectric device concepts.

Understanding the adhesion properties of carbon nanotube, asphalt binder, and mineral aggregates at the nanoscale: a molecular dynamics study

The adhesion properties of mineral aggregates (SiO2) and carbon nanotube (CNT) are estimated and compared with CNT-saturate, asphaltene, resin, and aromatic (SARA), SARA-SiO2 , and Graphene-SARA using molecular dynamics (MD) and reactive force field. The effect of electrostatic (ES), van der Waals (vdW) and bonded interactions on the adhesion properties at room temperatures are analyzed. The results show that the strength and work of adhesion for CNT-SARA is lower than Graphene-SARA as they provide less effective area. Also, vdW and ES interactions in SiO2-SARA and SiO2-CNT interfaces are equally important, while in CNT-SARA interface only vdW interactions have the major contribution.

Surface modification of ramie fibers with silanized CNTs through a simple spray-coating method

Preliminary studies performed have indicated that carbon nanotube (CNT) coating is an effective method to enhance the bonding between a natural fiber and a resin matrix. However, the reported coating process is complex, and the improvement of the bonding strength is limited owing to obvious CNT aggregation. This paper reports a simple spray-coating method with uniform distribution of CNTs coated on ramie fiber surfaces. The dispersion of CNTs in a suspension for spray-coating was found to play a key role in CNTs distribution on the fiber surface. Silylated CNTs can be stably and uniformly suspended in a water and alcohol solution with a polyvinylpyrrolidone dispersant. The suspension was sprayed onto ramie fabric by using a hand-spraying pot, and CNTs were distributed on the fiber surface uniformly, as indicated by scanning electron microscopy results. The agglomeration of CNTs on the fiber surface became increasingly evident with an increase in the number of spray layers (from one to six). The effects of CNT coating on the flexural properties of the related composite and bonding properties were studied. The CNT-coated ramie fiber reinforced epoxy plate was prepared by a vacuum assistant resin transfer molding method. The CNT coating increased the flexural strength and modulus of the composite by 38.4% and 36.8%, respectively. A microdebonding test showed that the CNT coating increased the interfacial shear strength between a single ramie fiber and the epoxy resin by 25.7%, which is believed to result from stronger mechanical interlocking and chemical bonding.

Dispersion, sedimentation and aggregation of multi-walled carbon nanotubes as affected by single and binary mixed surfactants.

Two commonly used dispersants, octyl phenol ethoxylate (Triton X-100) and sodium dodecyl sulfate (SDS), were employed to explore the effects of single or mixed surfactants on the dispersion, sedimentation and aggregation of multi-walled carbon nanotubes (MWCNTs). Non-ionic surfactant TX100 showed much superior capability to anionic surfactant SDS in dispersing MWCNTs due to the benzene ring structure in its tail group. The addition of SDS reduced the adsorption of TX100 on the surface of MWCNTs and the consequent suspension of MWCNTs. The dispersing ability of TX100–SDS binary mixture was between those of individual SDS and TX100. The introduction of SDS greatly retarded the sedimentation and aggregation of suspended MWCNTs. The critical coagulation concentration (CCC) values of suspended MWCNTs dispersed by TX100 (2000 mg l−1), SDS (2000 mg l−1) and TX100–SDS (2000 mg l−1 of each component) were 48.6, 398 and 324 mM, respectively, for Na+ treatments. The CCC values were much lower for Ca2+ treatments, which were 30.4 and 32.1 mM, respectively, for MWCNTs dispersed by TX100 and TX100–SDS mixture. Overall, these results demonstrated that although the introduction of SDS did not improve the ability of TX100 in suspending MWCNTs, the suspensions exhibited more stable properties than those dispersed by TX100 alone. Our findings have important implications for the design of surfactant mixtures and the prediction of the behaviour and fate of MWCNTs in the water environment.