Grafted Carbon Nanotubes Research Articles

A soft and recyclable carbon nanotube/carbon nanofiber hybrid membrane for oil/water separation

AbstractHydrophobic membranes have been considered as one of the most effective candidates in oil/water separation for their easy operation and high efficiency. Here, we prepared a hydrophobic carbon nanotube (CNT)/carbon nanofiber (CNF) hybrid membrane by in situ grafting CNTs on a CNF membrane. The CNT grafting significantly increased the porosity and hydrophobicity of the CNF membrane. As a result, the CNT/CNF hybrid membrane showed a high efficiency (80%–98%) in the separation of a range of oil/water mixtures. Moreover, the CNT/CNF hybrid membrane is recyclable, and the separation efficiency maintained after 10 cycles. This high separation efficiency and good recyclability provide feasibilities for practical applications of the CNT/CNF hybrid membrane in the purification of oil contaminated water.

A Robust Nanofilm Co-Assembled from Poly(4-Vinylpyridine) Grafted Carbon Nanotube and Gold Nanoparticles at the Water/Oil Interface as Highly Active Sers Substrate for Antibiotics Detection

A Robust Nanofilm Co-Assembled from Poly(4-Vinylpyridine) Grafted Carbon Nanotube and Gold Nanoparticles at the Water/Oil Interface as Highly Active Sers Substrate for Antibiotics Detection

Uniform Grafting of Amino-Functionalized Multi-Walled Carbon Nanotubes on the Surface of Oxidized Bamboo Fiber to Enhance the Interfacial Strength with Epoxy Resin

Uniform Grafting of Amino-Functionalized Multi-Walled Carbon Nanotubes on the Surface of Oxidized Bamboo Fiber to Enhance the Interfacial Strength with Epoxy Resin

Enhancing interfacial interactions of cocontinuous poly(lactic acid)/polyethylene blends using vinylsilane grafted carbon nanotubes as generic reactive compatibilizers

Enhancing interfacial interactions of cocontinuous poly(lactic acid)/polyethylene blends using vinylsilane grafted carbon nanotubes as generic reactive compatibilizers

Hydrothermally Synthesized Carboxylic Acid Functionalized Multiwalled Carbon Nanotubes Grafted Mos2 Based Hybrid Composites: Efficient Uranium (Vi) Scavenging Sorbents in Columns, Fabric and Matrix Membrane Systems

Hydrothermally Synthesized Carboxylic Acid Functionalized Multiwalled Carbon Nanotubes Grafted Mos2 Based Hybrid Composites: Efficient Uranium (Vi) Scavenging Sorbents in Columns, Fabric and Matrix Membrane Systems

Ethylenediamine grafted carbon nanotube aerogels modified screen-printed electrode for simultaneous electrochemical immunoassay of multiple tumor markers

• Hybrid carbon aerogels were synthesized and introduced for immunosensor application. • The sandwich configuration immunosensor was based on the screen-printed technology. • Redox mediators (dyes) have been used as labels. • The improved immunosensor was employed for individual and simultaneous electrochemical detection of AFP and CEA. • The developed EC sensor provided a sufficient linear range of 0.005–1.0 ng/mL for AFP and CEA. A sensitive sandwich-model immunoassay designed for simultaneous electrochemical measurement of alpha-fetoprotein and carcinoembryonic antigen handling multiple-label strategy. The sandwich-model immunosensor was constructed by assembling ethylenediamine-MWCNT aerogels (EDA-CAGs), AuNPs and capture antibodies (Cp-Ab 1 ) on the screen-printed carbon electrode (SPCE). The prepared EDA-CAG textures were analyzed using Fourier transform infrared (FT-IR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDX). In this protocol, AuNPs decorated EDA-CAG-carried Thionine (Thi) and AuNPs decorated EDA-CAG-carried Safranine O (SfO) (denoted as AuNP-Thi-EDA-CAG and AuNP-SfO-EDA-CAG, respectively) were properly exploited as distinguishable signal labels, which were used to attach detection antibodies (Ab 2 ) (anti-AFP 2 and anti-CEA 2 ), respectively. When two tumor antigens were present, a square wave voltammetry (SWV) scan displayed two well-separated signals, each signal indicated one target antigen. Observed results introduced that the square wave voltammetric peak current exhibited a good linear relationship to logarithm concentration in the ranges from 0.005 to 1.0 ng/mL for both analytes. The LoDs were 0.0015 and 0.0010 ng/mL (at signal/noise S/N = 3) for AFP and CEA, respectively. The designed sandwich-type immunosensor was applied to real serum sample analysis.

Ultrafine palladium nanoparticles supported on poly(4-vinylpyridine)-grafted carbon nanotubes as heterogeneous catalysts for cross-coupling reaction between organoindium halide and alkyl iodide

The rational design of a stable and recyclable nanocatalyst based on robust support for the application in palladium (Pd)-catalyzed coupling reactions always fuels great interest. Pd nanoparticles (NPs) deposited onto carbon nanotubes (CNTs) to form CNT–PdNPs hybrid nanocomposites has been thoroughly studied. And they can serve as heterogeneous catalysts to implement the Pd-catalyzed cross-coupling reactions. However, the utilization of CNT–PdNPs nanohybrids for cross-coupling reaction between organoindium halide and alkyl iodide is a blank area, and no example has been reported. In this work, we provide an effective approach for the fabrication of a Pd-based heterogeneous nanocatalyst, where Pd NPs with small average size (~2.5 nm) are uniformly immobilized on the surface of poly(4-vinylpyridine) (P4VP)-grafted carbon nanotube (CNT). Owing to the uniform distribution of Pd NPs on the CNT surface, high stability and good dispersibility of CNT-g-P4VP/PdNPs composites, the as-fabricated heterogeneous nanocatalyst exhibits excellent catalytic activity for cross-coupling of organoindium halide with alkyl iodide. It is the first report that the CNT–PdNP nanohybrid catalyst is applied to the cross-coupling reaction between organoindium halide and alkyl iodide. This work may pave the way for the construction of CNT-supported metallic NPs for a variety of efficient catalytic applications.

Polysulfone Mixed-Matrix Membranes Comprising Poly(ethylene glycol)-Grafted Carbon Nanotubes: Mechanical Properties and CO2Separation Performance

Polysulfone (PSF)-based mixed-matrix membranes (MMMs) were developed through incorporation by solvent casting of poly(ethylene glycol)-grafted carbon nanotubes (PEG-g-CNTs) into the polymer matrix. Single-gas permeability and the respective perm-selectivity values of the resulting MMMs for CO2, CH4, and N2 along with mixed-gas selectivities were determined at various temperatures and pressures. The performance was further analyzed by obtaining gravimetrically gas adsorption isotherms and interpreting the results to determine the solubility and diffusivity coefficients of the prepared membranes. Simultaneous improvement in CO2 permeability, selectivity, and mechanical robustness was achieved. Indicatively, an increase in CO2 permeability by 52.4% at 1.5 bar was discerned for the MMM containing 5 wt % PEG-g-CNTs along with enhancements of 81 and 74% in CO2/N2 and CO2/CH4 perm-selectivities, respectively, while an up to 43.4% increase in tensile modulus and a 12.5% increase in tensile strength were achieved as well. This performance, in conjunction with the stability of the fillers, and the low cost, structural stability, and commercial availability of the polymer make the PSF/PEG-g-CNT MMM a promising base case for developing industrially relevant CO2 separation membranes.

Eco-friendly synthesis of surface grafted Carbon nanotubes from sugarcane cubes for development of prolonged release drug delivery platform

Surface grafting of nanocarriers could modulate their properties and characteristics. As carbon nanotubes synthesis is a very tricky process and requires high-end methods, hence the present investigation was aimed to develop an eco-friendly method for synthesis carbon nanotubes (CNTs) and subsequent surface grafting for enhanced drug delivery application. The present study elaborates two-step chemical modifications; wherein the first step is catalytic cleavage of natural precursor in the presence of ferrocene and the second step involve chemical grafting of Acyclovir (ACV) as a model drug to understand the drug release behaviour. The catalytic cleavage of sugarcane cubes (natural precursor) was carried out in a closed copper tube, which prevents oxidation and results in a conversion of tubular nanostructures to amorphous carbon. The covalent attachment of ACV on purified CNTs (fCNTs) was done using carbodiimide chemistry. The preliminary Uv-Vis absorbance spectra defined at 260 nm was arised due to π-π* stacking of aromatic C-C bonds. The Fourier Transforms Infrared Spectroscopy (FTIR) indicated the hydroxyl stretch at 3300 cm-1 while amide I bond formation was observed at 1672 cm-1. The XRD spectra confirmed successful synthesis of CNTs. The calculated average crystallite size (Scherer equation) of synthesized CNTs was found to be 42.84 and 44.45 nm; it was also in accordance with the morphological observation as confirmed simultaneously using SEM analysis. The covalently attached ACV was released up to 80% during 8h of in vitro drug release study. The surface grafting potential of CNTs was found to be promising compared to other nanomaterials.

Highly Sensitive Hydrogen Peroxide Biosensor Based on Tobacco Peroxidase Immobilized on p‐Phenylenediamine Diazonium Cation Grafted Carbon Nanotubes: Preventing Fenton‐like Inactivation at Negative Potential

AbstractHerein, we present a novel electrode platform for H2O2 detection based on the immobilization of recombinant Tobacco Peroxidase (r‐TOP) onto graphite electrodes (G) modified with p‐phenylenediamine (p‐PD) diazonium cation grafted multi‐walled carbon nanotubes (MWCNTs). The employment of both p‐phenylenediamine moieties and covalent cross‐linking by using glutaraldehyde allowed us to enhance the sensitivity, stability, and selectivity toward H2O2 detection, as well as preventing enzyme inactivation due to the electro‐Fenton reaction. This reaction continuously produces hydroxyl radicals, whose high and unselective reactivity is likely to reduce drastically the operating life of the biosensor. The protection against the electro‐Fenton reaction is mainly ascribed to a beneficial enzyme immobilization leading to a correct orientation achieved through cross‐linking the enzyme in combination with interaction between the uncoupled ‐NH2 groups (mainly uncharged at pH 7, considering a pKa of 4.6) available on the electrode surface and the enzyme. In particular, the electrode based on the r‐TOP/p‐PD/MWCNTs/G platform showed a lower limit of detection of 1.8 μM H2O2, an extended linear range between 6 and 900 μM H2O2, as well as a significant increase in sensitivity (63.1±0.1 μA mM−1 cm−2) compared with previous work based on TOP. Finally, the r‐TOP/p‐PD/MWCNTs/G electrode was tested in several H2O2 spiked food samples as a screening analytical method for the detection of H2O2.

Optimization of Process Conditions for Continuous Growth of CNTs on the Surface of Carbon Fibers

Grafting carbon nanotubes (CNTs) is one of the most commonly used methods for modifying carbon fiber surface, during which complex device is usually needed and the growth of CNTs is difficult to control. Herein, we provide an implementable and continuous chemical vapor deposition (CVD) process, by which the novel multiscale reinforcement of carbon nanotube (CNT)-grafted carbon fiber is prepared. After exploring the effects of the moving speed and growth atmosphere on the morphology and mechanical properties of carbon nanotubes/carbon fiber (CNTs/CF) reinforcement, the optimal CVD process conditions are determined. The results show that low moving speeds of carbon fibers passing through the reactor can prolong the growth time of CNTs, increasing the thickness and density of the CNTs layer. When the moving speed is 3 cm/min or 4 cm/min, the surface graphitization degree and tensile strength of CNTs/CF almost simultaneously reach the highest value. It is also found that H2 in the growth atmosphere can inhibit the cracking of C2H2 and has a certain effect on prolonging the life of the catalyst. Meanwhile, the graphitization degree is promoted gradually with the increase in H2 flow rate from 0 to 0.9 L/min, which is beneficial to CNTs/CF tensile properties.

In-situ Growing Carbon Nanotubes on Nickel Modified Glass Fiber Reinforced Epoxy Composites for EMI Application

Glass fiber (GF) reinforced polymer composites have attracted increasing attention due to their excellent performance. In this study, GF was coated by a thin layer of nickel, and then grafted carbon nanotubes (CNTs) array by a chemical vapor deposition method (CVD). The CNT contents can be varied by changing the CVD conditions. Three types of fillers, nickel coated GF (GF@Ni), GF with CVD grown CNTs (GF-CNTs) and nickel-coated GF with CVD grown CNTs (GF@Ni-CNTs), were used to prepare the epoxy composites. The electromagnetic interference shielding performances were investigated as a function of CNT contents. The GF@Ni-CNTs reinforced epoxy composites, which had the CNTs mass ratio of 9.2 wt% to the hybrids, showed the best EMI shielding performance among the composites. Their total EMI shielding effectiveness (SE) was higher than 35 dB in the range of 1–18 GHz, and above 50 dB in the X band. By incorporating the nickel layer on the GF surface, the same EMI performance can be achieved with lower CNTs content. For achieving a SE value of 35 dB in the X band, it needed GF@Ni-CNTs/epoxy with CNTs mass ratio of 3.8 wt% to the hybrids, instead of GF-CNTs/epoxy composites with CNTs mass ratio of 5.2 wt% to the hybrids.

Modification of carbon nanotube with poly(amidoamine) dendritic structures to prepare a multifunctional hybrid curing component for epoxidized polyurethane and novolac resins

Dendritic poly(amidoamine) (PAMAM)-grafted carbon nanotube (CNTD), as a multifunctional hybrid curing component of epoxy-based resins, was prepared using a divergent method. Amino-functionalized CNT was utilized as a core for grafting the first generation of PAMAM dendritic structure by sequential addition of methyl acrylate and ethylenediamine. Epoxy-terminated polyurethane (EPU) and epoxidized novolac resin (ENR) were prepared and used as the epoxy-based polymers of the hybrid composite products. Proton nuclear magnetic resonance spectroscopy was used to study the structure of EPU. Fourier transform infrared spectra were used to prove each of the modification steps during preparation of CNTD. The characteristic peaks of CNTD at 1532 cm−1 originating from combination of stretching and bending vibrations of C–N and N–H bands, respectively, and the peaks at 2930 and 2859 cm−1 assigned to the stretching vibrations of C-H band of methylene groups confirms this claim. In addition, different char residues of CNT and CNTD in thermogravimetric analysis (TGA) curves confirmed addition of the organic parts and successful preparation of CNTD. Structural properties of the hybrid composites were investigated by X-ray diffraction analysis. The hard and soft segment contents of 34.46 and 65.54 wt% were obtained from X-ray diffraction curves. Char contents of 89.6 and 85.6% at 700 °C for the CNT and CNTD shows that the PAMAM modifier content is about 4 wt%. TGA thermograms of the hybrid composites revealed that thermal characteristics of the hybrid composite composed of ENR matrix and high content of CNTD are higher than the other hybrid composites. The ENR-based hybrid composite with 4 wt% of CNTD showed the highest char residue of 55.2% and degradation peak point of 413.6 °C. Morphology of the neat and PAMAM-modified nanotubes were also studied by scanning electron microscopy and transmission electron microscopy.

Investigation of Carbon Nanotube Grafted Graphene Oxide Hybrid Aerogel for Polystyrene Composites with Reinforced Mechanical Performance.

The rational design of carbon nanomaterials-reinforced polymer matrix composites based on the excellent properties of three-dimensional porous materials still remains a significant challenge. Herein, a novel approach is developed for preparing large-scale 3D carbon nanotubes (CNTs) and graphene oxide (GO) aerogel (GO-CNTA) by direct grafting of CNTs onto GO. Following this, styrene was backfilled into the prepared aerogel and polymerized in situ to form GO–CNTA/polystyrene (PS) nanocomposites. The results of X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy indicate the successful establishment of CNTs and GO-CNT and the excellent mechanical properties of the 3D frameworks using GO-CNT aerogel. The nanocomposite fabricated with around 1.0 wt% GO-CNT aerogel displayed excellent thermal conductivity of 0.127 W/m∙K and its mechanical properties were significantly enhanced compared with pristine PS, with its tensile, flexural, and compressive strengths increased by 9.01%, 46.8%, and 59.8%, respectively. This facile preparation method provides a new route for facilitating their large-scale production.

Balanced strength-toughness, thermal conductivity and self-cleaning properties of PMMA composites enabled by terpolymer grafted carbon nanotube

Achieving a balanced strength-toughness in polymer composites is a challenge largely because of poor interfacial interaction between the fillers and matrix. Here, we report that terpolymer grafted multi-wall carbon nanotubes (Ter-CNT) imparted good dispersion of CNT in matrix and strong CNT-matrix interaction. With the addition of 2 vol% filler into polymethyl methacrylate (PMMA) matrix, the composite exhibited simultaneously a balanced strength-toughness property with flexural strength of 72.3 MPa, toughness of 10.1 MJ m−3, which increased by 40.1% and 578% compared with those of pure PMMA. In addition, the composite also shows a high static contact angle (110.3°), and thermal conductivity (0.50 Wm K−1), which endow the composite with good self-cleaning and thermal management capabilities. Thus, this preparation process shows guidance for the design of polymer composite with integrated high strength-toughness, thermal conductivity and good self-cleaning.

Mixed Matrix CO2 Separation Membranes based on Polysulfone with Cu-BTC Metal-Organic Framework and Poly(ethylene glycol)-grafted-Carbon Nanotubes

Mixed matrix membranes (MMMs) are heterogeneous membranes comprised of inorganic fillers distributed in a polymer matrix, and have been receiving considerable attention in gas separation. The objective is to take advantage of the benefits provided by each phase that can include high selectivity and permeability due to the inorganic fillers, economical processability of the polymers, and enhanced mechanical properties. Yet, the advancement of MMMs is mostly challenged by the fabrication of defect-free membranes, the proper filler dispersion, and the selectivity/permeability trade-off. In this work, we have developed polysulfone (PSF) MMMs by exploring two different fillers, namely, Cu-BTC (HKUST-1) metal-organic framework and polyethylene glycol-grafted-carbon nanotubes (PEG-g-CNTs) via solvent casting. Following morphological and structural characterization of the developed PSF/HKUST-1 and PSF/PEG-g-CNTs membranes, their CO2 separation performance was evaluated in a gas permeation rig in terms of permeance and selectivity for three different gases, namely, CO2, CH4 and N2 at 2.5 bar and room temperature. Indicatively, an increase in CO2 permeance by 23% was obtained for the MMM containing 10 wt% of HKUST-1, while for the one loaded with 10 wt% of PEG-g-CNT, an increase in CO2 permeance by 35% was observed.

Immobilization of Gold Nanoparticles on Poly(4-vinylpyridine)-Grafted Carbon Nanotubes as Heterogeneous Catalysts for Hydrogenation of 4-Nitrophenol

The organization of colloidal nanoparticles (NPs) on suitable supports is very significant for applications. In this work, a facile and robust method has been developed to directly attach gold NPs ...

Wettability of thermoplastic and thermoset polymers with carbon nanotube grafted carbon fiber

In this experimental study the wetting behavior of unsized and carbon nanotube (CNT) grafted carbon fibers is assessed with various polymers. Thermoset epoxy and two thermoplastics (polypropylene and polycarbonate) are tested. Sessile drop method and drop-on-fiber method are employed to quantify the wettability of various fiber/polymer combinations. Contact angle measurements based on the above two methods give insights into the effectiveness of various polymers to wet different types of carbon fiber fabrics and single fiber filaments. Moreover, the effect of CNT length and density on the wettability of carbon fibers is ascertained by synthesizing nanotubes on the fiber surface for varying time durations (10–30 min). CNT grafting reduces the contact angle of the polymer drop with carbon fiber; however, too much growth of nanotubes on the fiber surface leads to improper impregnation of the polymer into the carbon fabric. While polypropylene shows better wetting characteristics with unsized and CNT grafted carbon fibers, polycarbonate shows poor wettability.

Getting self-healing ability and ultra-low dielectric loss for high-k epoxy resin composites through building networks based on Li0.3Ti0.02Ni0.68O grafted carbon nanotube bundles with unique surface architecture

Getting self-healing ability and ultra-low dielectric loss is effective to achieve high service reliability and sustainable development for high dielectric constant (high-k) polymer composites. Herein, new functional fillers with special surface architecture (sLTNO@mAC) were synthesized by grafting Li0.3Ti0.02Ni0.68O particles (sLTNO) on surfaces of carbon nanotube bundles (mAC), which was then embedded in epoxy resin (EP) with disulfide bonds to develop new composites (sLTNO@mAC/EP). Compared with composites based on mAC (mAC/EP) or a blend of sLTNO and mAC (sLTNO/mAC/EP) with the same filler loading, sLTNO@mAC/EP composites have much higher dielectric constant and self-healing efficiency as well as much lower dielectric loss at the same frequency. For the composite based on sLTNO@mAC with 8.2 wt% of sLTNO, coded as sLTNO1@mAC/EP, its dielectric loss is only 0.02, about 1.1 × 10 -3 and 9.4 × 10 -3 times of that of mAC/EP and sLTNO/mAC/EP, respectively; meanwhile its dielectric constant (216.1, 100 Hz) is the highest value among self-healable dielectric composites reported so far, and sLTNO1@mAC/EP has higher self-healing efficiency (97.7%) than mAC/EP and sLTNO/mAC/EP. The mechanism behind these attractive properties reveals that dielectric properties of sLTNO@mAC/EP mainly depend on interface polarization, while those of mAC/EP and sLTNO/mAC/EP are mainly related to the integrity of conductive networks.

On the role of carbon nanotubes addition in carbon fiber-reinforced magnesium matrix composites

Introducing carbon nanotubes (CNTs) to form a multiscale reinforcing structure is regarded as an unique approach to effectively improve the interface property of metal matrix composites. Curved CNTs were grafted onto the surface of the carbon fiber fabrics by injection chemical vapor deposition, and pieces of fabrics were further stitched into preform. Carbon fiber grafted with CNTs-reinforced magnesium matrix composites (CNTs-Cf/Mg) was prepared by squeeze casting. The influence of grafted CNTs on the interfacial microstructure and mechanical properties was investigated. The results showed that the carbon fiber preform grafted with CNTs was fully infiltrated with the melt matrix alloy. The larger Al8Mn5-phase particles were refined by grafted CNTs, and a transition layer of Al8Mn5/CNTs was formed on the surface of carbon fiber. Tensile strength and bending strength of the CNTs-Cf/Mg composite were significantly increased compared to the composite without grafted CNTs by 33% and 29%, respectively. The fracture morphologies confirmed that the enhanced plasticity of matrix alloy near the interface prevented obvious debonding after grafting CNTs on carbon fiber. The main operative mechanism by CNTs was attributed to optimized interface fracture behavior. This could be a very prominent method to adjust the interface structure and improve the properties of composites.