Functionalization Of Multi-walled Carbon Nanotubes Research Articles

Superior electromagnetic interference shielding effectiveness of functionalized MWCNTs filled flexible thermoplastic polymer nanocomposites

Carbon nanotubes (CNTs) impart great multi-functionality when reinforced with a polymer matrix. This paper shows the qualitative and quantitative improvements of the mechanical, electrical, and electromagnetic interference shielding effectiveness properties with the additions of the multiwalled carbon nanotubes (MWCNTs) and functionalized MWCNTs (FMWCNTs) in ethylene methyl acrylate (EMA) polymer. Mechanical characterization is performed through tensile testing, and electromagnetic interference shielding effectiveness (EMI SE) is calculated from the scattering parameters obtained from the vector network analyzer. Both properties improve compared to neat polymer with the reinforcement loadings up to a critical value, from where the properties start to degrade due to the agglomeration of the CNTs. FMWCNTs provide better performance in terms of properties over the MWCNT reinforced nanocomposites. Morphological characterization using a scanning electron microscope justifies a lower percolation threshold of FMWCNT/EMA composite by better electrical conductive network formation. At 10 wt% of FMWCNT loading, the FMWCNT/EMA composite shows 25.1 dB of EMI shielding efficiency combined with excellent mechanical and electrical properties extending its potential use in both industry and academia as an excellent flexible EMI shielding material.

Experimental investigations to enhance the tribological behaviour of biodegradable oil by using manganese doped ZnO/FMWCNTs nanomaterials as lubricant additive

A novel binary hybrid nanomaterial of functionalized multi-walled carbon nanotubes (FMWCNTs) anchored on the surface of manganese doped zinc oxide nanosheets Mn0.10ZnO0.90 (MnZnO) were synthesized by using simple hydrothermal method. Further, the nanomaterials such as zinc oxide (ZnO), functionalized multiwalled carbon nanotubes (FMWCNTs) and ZnO/FMWCNTs hybrid nanomaterials have also been considered to evaluate the influence of doping of manganese in ZnO nanosheets on the tribological properties. The individual nanomaterials and synthesized hybrid nanomaterials were characterized by employing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), Thermo gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) techniques. The tribological performances of ZnO nanoparticles, FMWCNTs, ZnO/FMWCNTs and MnZnO/FMWCNTs hybrid nanomaterials dispersed in castor oil were investigated by a reciprocating ball on disk tribo tester. The castor oil with optimum concentration of 0.10 wt% MnZnO/FMWCNTs hybrid nanomaterials exhibited the superior tribological performance than the castor oil, ZnO, FMWCNTs and ZnO/FMWCNTs hybrid nanomaterial additives and reduced the coefficient of friction and wear volume by 26.21 % and 89.09 % respectively. The outstanding lubricating behaviour of MnZnO/FMWCNTs hybrid nanomaterial are corresponds to the synergistic mechanism of Mn doped ZnO nanosheets and FMWCNTs and formation of boundary film on the frictional surface. The surface characteristics and chemical composition of the worn bronze specimen lubricated with various nanomaterial additives have been examined using FESEM, EDS, optical profilometer and X-ray photoelectron spectroscopy.

A comparative study on thermophysical properties of functionalized and non-functionalized Multi-Walled Carbon Nano Tubes (MWCNTs) enhanced salt hydrate phase change material

Thermal energy storage (TES) system is one of the best options for harvesting, storing, and saving energy for long-term or short-term use of a modern energy production system. The nano-enhanced phase change materials (NePCM) are a new type of phase change materials (PCM) formed by suspended nano-sized particles in base PCM to improve the thermophysical properties of the base PCM. The major challenge in nanoparticle dispersion in PCM, especially for solar energy applications, is its poor thermal conductivity and light transmission capability. Present research aims to address the thermal conductivity and light transmission capability issues by dispersing pristine multi-walled carbon nanotube (MWCNT) and functionalized multi-walled carbon nanotube (FMWCNT) particles in various weight concentrations (0.1, 0.3, 0.7, and 1.0%) into the salt hydrate PCM. A two-step technique was implemented to develop the NePCM for various weight percentage of MWCNT and FMWCNT. The Fourier transform infrared (FTIR) spectrum shows the MWCNT and FMWCNT nano-sized particles physically mixed well in salt hydrate PCM and without disturbing the chemical properties. The thermal conductivity of developed composites at 0.7 wt% MWCNT/S50 (S50M-0.7) and 0.7 wt% FMWCNT/S50 (S50F-0.7) are 0.78 W/mK, and 0.92 W/mK, respectively. The Differential Scanning Calorimetry (DSC) results revealed that the maximum improvement in latent heat by 14.66% and 31.17% for 0.1 wt% MWCNT/S50 (S50M-0.1) and 0.3 wt% FMWCNT/S50 (S50F-0.3) respectively. Light transmittance of S50M-0.7 and S50F-0.7 reduced to 92% and 93.49% than pure salt hydrate PCM. It exhibits the reduction in transmittance, greater improvement in solar spectrum absorption, and excellent photothermal conversion. • Study on Functionalized and non-Functionalized MWCNT enhanced PCM. • Comparative thermal performance of MWCNT and FMWCNT enhanced salt hydrate PCM. • A remarkable enhancement in thermal conductivity by 100% for S50F-0.7 • A substantial reduction in light transmittance by 93.49% for S50F-0.7 than base PCM.

Quantitative adverse outcome pathway (qAOP) using bayesian network model on comparative toxicity of multi-walled carbon nanotubes (MWCNTs): safe-by-design approach

While the various physicochemical properties of engineered nanomaterials influence their toxicities, their understanding is still incomplete. A predictive framework is required to develop safe nanomaterials, and a Bayesian network (BN) model based on adverse outcome pathway (AOP) can be utilized for this purpose. In this study, to explore the applicability of the AOP-based BN model in the development of safe nanomaterials, a comparative study was conducted on the change in the probability of toxicity pathways in response to changes in the dimensions and surface functionalization of multi-walled carbon nanotubes (MWCNTs). Based on the results of our previous study, we developed an AOP leading to cell death, and the experimental results were collected in human liver cells (HepG2) and bronchial epithelium cells (Beas-2B). The BN model was trained on these data to identify probabilistic causal relationships between key events. The results indicated that dimensions were the main influencing factor for lung cells, whereas -OH or -COOH surface functionalization and aspect ratio were the main influencing factors for liver cells. Endoplasmic reticulum stress was found to be a more sensitive pathway for dimensional changes, and oxidative stress was a more sensitive pathway for surface functionalization. Overall, our results suggest that the AOP-based BN model can be used to provide a scientific basis for the development of safe nanomaterials.

TEMPO-Functionalized Carbon Nanotubes for Solid-Contact Ion-Selective Electrodes with Largely Improved Potential Reproducibility and Stability.

Solid-contact ion-selective electrodes (SCISEs) can overcome essential limitations of their counterparts based on liquid contacts. However, attaining a highly reproducible and predictable E0, especially between different fabrication batches, turned out to be difficult even with the most established solid-contact materials, i.e., conducting polymers and large-surface-area conducting materials (e.g., carbon nanotubes), that otherwise possess excellent potential stability. An appropriate batch-to-batch E0 reproducibility of SCISEs besides aiding the rapid quality control of the electrode manufacturing process is at the core of their “calibration-free” application, which is perhaps the last major challenge for their routine use as single-use “disposable” or wearable potentiometric sensors. Therefore, here, we propose a new class of solid-contact material based on the covalent functionalization of multiwalled carbon nanotubes (MWCNTs) with a chemically stable redox molecule, (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). This material combines the advantages of (i) the large double-layer capacitance of MWCNT layers, (ii) the adjustable redox couple ratio provided by the TEMPO moiety, (iii) the covalent confinement of the redox couple, and (iv) the hydrophobicity of the components to achieve the potential reproducibility and stability for demanding applications. The TEMPO-MWCNT-based SC potassium ion-selective electrodes (K+-SCISEs) showed excellent analytical performance and potential stability with no sign of an aqueous layer formation beneath the ion-selective membrane nor sensitivity toward O2, CO2, and light. A major convenience of the fabrication procedure is the E0 adjustment of the K+-SCISEs by the polarization of the TEMPO-MWCNT suspension prior to its use as solid contact. While most E0 reproducibility studies are limited to a single fabrication batch of SCISEs, the use of prepolarized TEMPO-MWCNT resulted also in an outstanding batch-to-batch potential reproducibility. We were also able to overcome the hydration-related potential drifts for the use of SCISEs without prior conditioning and to feature application for accurate K+ measurements in undiluted blood serum.

RAPID ELECTROCHEMICAL DETECTION OF CARBENDAZIM IN VEGETABLES BASED ON CARBOXYL FUNCTIONALIZED MULTI-WALLED CARBON NANOTUBES

At present, the commonly used methods for the detection of benzimidazole fungicides include high performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS), fluorescence spectrometry and so on. These methods have high sensitivity and accurate results, but they have disadvantages such as complicated pretreatment, long time consuming, expensive equipment and professional operators. Electrochemical sensor detection method has the advantages of high sensitivity, simple operation, low cost and easy on-site inspection, etc., which has attracted extensive attention in the field of pesticide residue detection and analysis. In order to realize the rapid detection of carbendazim content in vegetables, an electrochemical rapid detection method was established by using Carboxyl Functionalized Multi-Walled Carbon Nanotubes (MWCNTs-COOH) modified glassy carbon electrode. In this study, MWCNTs-COOH with special functional groups and large specific surface area were used to modify electrodes to improve the adsorption and enrichment of CBZ on the electrode and amplify the electrochemical signal, aiming to establish a highly sensitive electrochemical rapid detection technology for CBZ. The results showed that: the modified electrode functionalized with MWCNTs-COOH could significantly improve the electron transfer rate on the electrode surface, which made the detection sensitivity of carbendazim higher. The linear range of detection was 0,3 μM~20 μM, and the detection limit was determined as low as 0,06 μM. In this study, MWCNT-COOH with better conductivity, adsorption and stability was used to modify electrode, and constructed the MWCNT-COOH/GCE, which improved the adsorption and accumulation of CBZ, effectively promoted the electron transfer on the surface of the electrode, accelerated the response speed of the electrode and improved the current response, to realize the rapid and sensitive detection of trace CBZ in vegetables. This method had high sensitivity, good anti-interference, and detection stability. It was of great significance to detect carbendazim in vegetables.

Electrochemical functionalization at anodic conditions of multi-walled carbon nanotubes with chlorodiphenylphosphine

Covalent functionalization of multi-walled carbon nanotubes (MWCNTs) and oxidized MWCNTs (o-MWCNTs) with chlorodiphenylphosphine (Ph2PCl) has been studied by cyclic voltammetry in organic medium. Depending the upper potential limit used in the electrochemical functionalization, different amount of phosphorus incorporation n is obtained, as result of the formation of radical species during the electrochemical oxidation of the Ph2PCl. The electrochemical oxidation of Ph2PCl promotes the covalent attachment of diphenylphosphine-like structure on the carbon nanotube surface. At the same time, the incorporation of Cl on the carbon nanotubes is observed during the functionalization. Furthermore, the presence of oxygen surface groups on the MWCNTs provides a favorable attachment of the Ph2P∙+ species, which has promoted preferentially the formation of CP bonds, whereas the amount of Cl is reduced.

Influence of MWCNTs on strength properties of high viscous epoxy adhesive and fracture behavior of adhesively bonded joints

In this research, the combined effects of Multi-Walled Carbon Nanotubes (MWCNTs) addition, functionalization, and filler concentration on mechanical properties of high viscous structural adhesive and strength characteristics of adhesively bonded joints were experimentally investigated. Two configurations of lap joints: single lap joint (SLJ) and double lap strap joint (DLSJ) were manufactured with Araldite 2011 adhesive. Aluminum alloy 5083 was used as adherends in the fabrication of the lap joints. Non-functionalized, carboxylate (COOH), and amine (NH2) functionalized MWCNTs were added in amounts of 0.25, 0.5, 0.75, and 1 wt% in the host resin. Solution mixing technique was used for mixing of MWCNTs in the host resin. The prepared adhesive was then used to make bulk adhesive samples and lap joints. The strength properties of epoxy adhesive and lap shear joints were determined by tensile testing of the specimens. For adhesive, a maximum reduction of 54% in elastic modulus and 23% in tensile strength was observed with the addition of 1 wt% functionalized MWCNTCOOH. The decrease in strength was inversely related to failure strain, consequently increasing the toughness characteristics of the adhesive. The lap joints showed a significant improvement in joint strength with the added MWCNTs. A maximum improvement of 60% for SLJ and 31% for DLSJ was observed with the addition of 1 wt% non-functionalized MWCNTs. ANOVA study was performed for the evaluation of data variation and interaction. Optical and Scanning Electron Microscopy (SEM) was utilized for the analysis of fracture surfaces, and the correlation between nano-reinforcement and strengthening mechanisms was critically discussed.

Composites Made of Carbon Nanotubes and Silver Nanoparticles for Conductive Aerosol-Jet Deposition Ink: The Double-Edged Sword of Functionalization

Optimizing conductive ink for Direct-Write Additive Manufacturing, this work explores the effect of carboxylic functionalization of multi-walled carbon nanotubes on their affinity to silver nanoparticles deposited on them. We show a correlation between functionalization and the size of the resulted NPs: the diameter of the silver NPs deposited on pristine CNTs (∼5 nm diameter) is third of that of NPs deposited on functionalized CNTs (∼15 nm). Electrical characterization of the silver-decorated CNT-based ink shows a more significant improvement in conductivity of the functionalized CNTs-decorated with silver compared to the pristine one (maximal ∼40 and ∼20% increase in conductivity over their undecorated counterpart, respectively). However, CNT functionalization severely damages the conductivity of the CNTs themselves, resulting in a much lower conductivity. This “double-edged sword” effect of functionalization results in the highest absolute specific conductivity (3.79 × 103 S/m) achieved by decorating pristine CNTs with 25 wt% of silver. Nevertheless, the observed enhanced conductivity and the ability to control the composite’s morphology by functionalization allow fine-tuning of morphology-based properties, such as surface enhanced Raman scattering and optimization of the ink for sensing applications.

Compare Performance MWCNT-OH Network as a Gas Sensor of Embedded Nanoparticles when Exposed (NH3, NO2) Gases

This study is about gas sensor preparation of hydroxyl functionalized multiwall carbon nanotubes (MWCNTs-OH) network use filtration from suspension (FFS) method. Improve the properties of the sensor use embedded nanoparticles (PANI, Pt-CNT active, Ni). the gas sensor good responce toward Exposure (NH3, NO2) gases at room temperature and at low concentration (1ppm). The sensor was more responsive when exposure to NO2 gas because it is an oxidizing gas(corroded), When exposure NH3 gas for concentration (1ppm ) and embedded Ni NP the sensitivity value (3.41, 3.49, 9.7 and 5.4) % at the temperatures (RT, 50, 100 and 150 ) C˚. The recovery time was decreases at (150)C˚ as it was (5.4)sec , the factors to improve the properties of the sensor was increase temperature and embedded NPs.

Thermal conductivity, reliability, and stability assessment of phase change material (PCM) doped with functionalized multi-wall carbon nanotubes (FMWCNTs)

The thermal properties of Phase Change Material (PCM) can be altered by introducing nanoparticles, and composite formed from the addition of nanoparticles are termed Nano-Enhanced Phase Change Materials (NEPCM). In the present study, the enhancement of thermal conductivity and feasibility study of dispersing multi-walled carbon nano tubes (MWCNTs) and functionalized MWCNT (FMWCNTs) in various mass fractions (AFMW-0.1, AFMW-0.3, AFMW-0.5, AFMW-0.7, AFMW-1.0) into the Plusice A70 PCM were examined. Differential scanning calorimetry (DSC) and TEMPOS thermal analyzer measured the latent heat storage, melting temperature, and thermal conductivity of the nano PCM composite. The thermal conductivity measured for the prepared nanocomposite showed a 109.5% enhancement for 1.0 wt% of non-functionalized MWCNT and 150.7% enhancement for 1.0 wt% of functionalized MWCNT compared to pristine PCM's thermal conductivity. This statement concluded that 50% enhancement for a 1.0 wt% of functionalized MWCNT compared to non-functionalize MWCNT immersed in A70 PCM. The nano composite PCM was thermally stable up to 200 °C and no chemical reaction takes place between the base PCM and nanoparticles. The result shows that the microscopic structure remained stable for the nanocomposite while the optical transmittance reduced noticeably for the nanocomposite relative to pristine A70 PCM. It can be concluded, the prepared nano composite PCM may be useful for solar thermal, photovoltaic thermal system, and low concentrated photovoltaic thermal system applications.

Functionalization of Multi-walled Carbon Nanotubes–Silver Nanoparticle (MWCNTs-AgNPs) as a Drug Delivery System for Ibuprofen

Nanoparticle utilization for the prevention, diagnostics, and treatment of diseases is widely known as one of the medicine branches, nanomedicine. The ability to penetrate the higher space between cells and cell walls makes nanoparticles have the potential to be used as a drug delivery system (DDS). Furthermore, various techniques can be combined with nanoparticles due to their flexibility. AgNPs are one of the interesting nanoparticles to be developed into DDS. It is because they can improve antibacterial, antiviral, antifungal, antioxidant, and physicochemical properties. In addition, AgNPs have biocompatibility that can improve drug delivery capability. On the other hand, carbon-based nanomaterials such as MWCNTs have unique properties that can be potentially used as composite materials for application as DDS. Therefore, to increase the ability of DDS, the in-situ synthesis of MWCNT-AgNPs nanocomposites was carried out. UV-Vis observed the absorption peak of the nanocomposite. The characterization of the crystal structure was performed using XRD. FESEM-EDX conducted the determination of the morphology of nanocomposite and the chemical composition. The distribution of AgNPs on the MWCNTs surface was performed by TEM. Furthermore, Raman spectroscopy was used to investigate the vibration of the MWCNT-AgNPs. Drug Loading was performed using UV-Vis measurements. The results showed that MWCNT-AgNPs as a DDS are successfully created in the drug loading stage. Drug loading stage properties are increased with the increasing loading time of Ibuprofen on MWCNT-AgNPs. The optimum percentage of drug loading for Ibuprofen by MWCNTs-AgNPs was 43.7% in a contact time of 27 hours.

The covalent attachment of Naltrexone to multi-walled carbon nanotubes byoxalyl chloride agent

This work presents a novel cascade of chemical functionalization of multi-walled carbon nanotubes(MWCNTs) through chemical modification by an opioid antagonist drug of Naltrexone. Naltrexone-conjugated MWCNTs were synthesized involving the sequential steps of carboxylation, acylation,and finally,Naltrexoneconjugation.The active acyl chlorides in MWCNTs were subsequently mixed with opioid antagonist drug of Naltrexone.The modification of MWCNTs with Naltrexone was investigated by Fourier transform-infrared spectroscopy,Raman spectroscopy,Thermo Gravimetric Analysis,Elemental Analysis,High Performance Liquid Chromatography.Size and surface characteristics of chemically modified MWCNTs were monitored by Transmission Electron Microscopy,Scanning Electron Microscopy,Field Emission Scanning Electron Microscopy,Atomic Force Microscopy.

The attachment opioid antagonist drug of Naltrexone to multi-walled carbon nanotubes by different kinds of reagents carbodiimides

Surface functionalization of multi-walled carbon nanotubes(MWCNTs) by opioid antagonist drug of Naltrexone via chemical modification of carboxyl groups,using of reagents di cyclohexyl carbodiimide(DCC),1-ethyl-3[3-dimethylaminopropyl] carbodiimide hydrochloride(EDC),N-hydroxysuccinimide(NHS),1-hydroxybenzotriazolemonohydrate(HOBT),O-(Benzotriazole-1-yl)-1,1,3,3-tetramethyluraniumtetrafluoroborate(TBTU),were performed. In synthetic organic chemistry,compounds containing the carbodiimide functionality are dehydration agents and are often used to activate carboxylic acids towards amide or ester formation. Carboxylic acids will react with the carbodiimide to produce the key intermediate as O-acylisourea which can be considered as a carboxylic ester with an activated leaving group.We have used of five carbodiimide reagent to synthesis twelve sample in this work.The resulting materials were characterized by different techniques,such as Fourier transform infraredspectroscopy (FT-IR), Thermogravimetricanalysis (TGA),Raman spectroscopy,Scanning Electron Microscopy (SEM),Field Emission Scanning Electron Microscopy(FESEM),Atomic Force Microscopy(AFM),High performance liquid chromatography(HPLC).

Evaluation of different organosilanes on multi-walled carbon nanotubes functionalization for application in cementitious composites

Organosilanes can be used as coupling agents between carbon nanotubes (CNTs) and the major hydration product of Portland Cement, calcium silicate hydrate, overcoming the low interfacial interaction of these nanomaterials with the cementitious matrix. Nevertheless, the modification of CNTs with silane has not yet been extensively investigated for cementitious composites application. Thus, this work investigated the CNTs functionalization using four different organosilanes (APTES, AEAPTMS, GPTMS and TEOS) for application in cement pastes. The results showed that only APTES and AEAPTMS effectively functionalized CNTs surface. Cement pastes were produced by adding 0.1% (w/w) of non-silanized and silane-functionalized CNTs and evaluated through rotational rheometry, isothermal calorimetry, compressive strength, and water absorption. CNTs silanization with APTES and AEAPTMS reduced the agglomeration trend of nanotubes at pH 12 as suggested by DLS results, which reduced the dynamic yield stress, equivalent viscosity, and hysteresis area compared to non-silanized CNTs cementitious composite. Furthermore, cement pastes with functionalized nanotubes increased the 28-day compressive strength by 13.3% and 20.2% and reduced the volume of permeable voids by 1.8% and 2.7% when using APTES and AEAPTMS, respectively, compared to plain cement paste. Overall, silanization can reduce the agglomeration trend of carbon nanotubes and improve the interface with cementitious matrix, improving the fresh and hardened properties of cement-based materials compared to non-silanized CNTs.

Humic acid non-covalent functionalized multi-walled carbon nanotubes composite membrane and its application for the removal of organic dyes

It was the first time that humic acid (HA) was used to non-covalent functionalize multi-walled carbon nanotubes (MWCNTs). The MWCNT and HA-MWCNT was characterized by X-ray photoelectron spectroscopy (XPS), infrared spectra (IR) and transmission electron microscopy (TEM). Then, a HA non-covalent functionalized multi-walled carbon nanotubes (HA-MWCNTs) membrane was prepared by vacuum filtration and used to remove organic dyes. To investigate the removal mechanism of organic dyes by HA-MWCNTs membrane, the dynamic filtration effectiveness of HA-MWCNTs membrane was compared with the adsorption ability of HA-MWCNTs. The results proved that HA-MWCNTs membrane had a higher effectiveness for the removal of dyes as it had shorter filtration time compared with the static adsorption experiment. Especially, the HA-MWCNTs membrane had a higher removal efficiency for cationic dye methylene blue (MB) than the raw MWCNTs (P-MWCNTs) membrane. The electrostatic interaction played an important role on the removal of MB, and the functionalization of MWCNTs with HA increased the surface electronegativity of MWCNTs membrane, and promoted the removal of MB during filtration process. As for RB19, in addition to π–π stacking interaction, electrostatic interaction also influenced its removal by MWCNTs membrane. Compared with P-MWCNTs membrane, HA-MWCNTs membrane slightly decreased the effectiveness of RB19 removal during filtration due to the increased electrostatic repulsion. Generally, the dynamic membrane filtration based on MWCNTs composite membrane could avoid the ecological risk caused by the release of MWCNTs. It provided a new idea for the further innovation of low-pressure membrane technology in the field of dye wastewater treatment.

Biosensing Efficiency of Nanocarbon-Reinforced Polyacrylonitrile Nanofibrous Matrices

The reinforcement of polymer matrices with nanocarbon fillers is highly attractive for electrochemical biosensing (due to enhanced electrical conductivity). Further processing by electrospinning results in versatile nanofibrous mats. This study compares the biosensing performance of composite polyacrylonitrile nanofibers (PAN NFs) electrospun with different carbonaceous fillers (fullerene, carbon nanotubes, graphene). Morphological characterization of the composite NFs is performed by scanning electron microscopy (SEM) and correlated with the performance of the biosensing matrices. Glucose oxidase (GOD) is employed as model enzyme by immobilization through cross-linking. Optimum nanofiller content was evaluated at 2.0 wt%. for carboxyl functionalized-multiwall carbon nanotubes- NFs (highest sensitivity of 61.5 mAM−1cm−2 and limit of detection (LOD) of 2.0 μM), whilst reduced graphene oxide- NFs exhibited 49.3 mAM−1cm−2 sensitivity with the lowest LOD of 1.6 μM within the most extended linear range (up to 20 × 10−3 M). Insignificant effect of interferent sugars led to real sample recovery close to 100%.

Comparing Commercial Metal-Coated AFM Tips and Home-Made Bulk Gold Tips for Tip-Enhanced Raman Spectroscopy of Polymer Functionalized Multiwalled Carbon Nanotubes.

Tip-enhanced Raman spectroscopy (TERS) combines the high specificity and sensitivity of plasmon-enhanced Raman spectroscopy with the high spatial resolution of scanning probe microscopy. TERS has gained a lot of attention from many nanoscience fields, since this technique can provide chemical and structural information of surfaces and interfaces with nanometric spatial resolution. Multiwalled carbon nanotubes (MWCNTs) are very versatile nanostructures that can be dispersed in organic solvents or polymeric matrices, giving rise to new nanocomposite materials, showing improved mechanical, electrical and thermal properties. Moreover, MWCNTs can be easily functionalized with polymers in order to be employed as specific chemical sensors. In this context, TERS is strategic, since it can provide useful information on the cooperation of the two components at the nanoscale for the optimization of the macroscopic properties of the hybrid material. Nevertheless, efficient TERS characterization relies on the geometrical features and material composition of the plasmonic tip used. In this work, after comparing the TERS performance of commercial Ag coated nanotips and home-made bulk Au tips on bare MWCNTs, we show how TERS can be exploited for characterizing MWCNTs mixed with conjugated fluorene copolymers, thus contributing to the understanding of the polymer/CNT interaction process at the local scale.

Facile grafting hyperbranched poly(thiol ether‐ester) onto multiwalled carbon nanotubes (MWCNTs) via thiol‐yne click chemistry to enhance the thermal conductivity, mechanical, and thermal properties of MWCNTs/epoxy composites

AbstractIn this study, we report an efficient and rapid technique to achieve the covalent functionalization of multiwalled carbon nanotubes (MWCNTs) by hyperbranched poly(thiol ether‐ester) (HPTEE) via thiol‐yne click chemistry method. The structures of the MWCNTs grafted with HPTEE (MWCNTs‐HPTEE) were characterized and their effects on the epoxy‐based composites were investigated. It was found that the hyperbranched polymers have been successfully grafted onto the MWCNTs surface thorough covalent bonds, which can greatly improve the dispersion of MWCNTs in epoxy matrix and the interfacial interaction between them, contributing to the largely enhanced mechanical and thermal properties. When 0.6 wt% MWCNTs‐HPTEE was added, the composites exhibited the best mechanical properties. An impressive 180% increase in the impact strength and 72.3% increase in flexural strength were observed with respect to the neat epoxy resin. Moreover, at the same filler content, the thermal stability and thermal conductivity of MWCNTs‐HPTEE/epoxy composites outperformed the composites containing the raw MWCNTs. Experimental results demonstrated that the resulted MWCNTs‐HPTEE are more effective on the improvement of properties of epoxy‐based composites as compared with raw MWCNTs.

Impact of a new functionalization of multiwalled carbon nanotubes on antifouling and permeability of PVDF nanocomposite membranes for dye wastewater treatment

Here, novel hydroxyl and carboxyl functionalized multiwalled carbon nanotubes (AHF-MWCNT and ACF-MWCNT) were successfully synthesized and introduced for modification and antifouling improvement of the PVDF membrane. The blending effect of AHF-MWCNT and ACF-MWCNT on the morphology and surface properties of the PVDF membrane was explored by SEM, AFM, water contact angle, and zeta potential analysis. The results indicated that the membrane surface has become more hydrophilic, smoother as well more negative. In addition, the overall porosity and mean pore radius are increased by MWCNTs embedding. The filtration performance, antifouling and dye separation of the nanocomposite membranes were improved by adding any amounts of AHF-MWCNT and ACF-MWCNT in the PVDF membrane matrix. The carboxylic modification presented better performance than the hydroxyl functionalization. The 0.1 wt% ACF-MWCNT blended membrane presented an optimum performance with 46 L m−2 h−1 bar−1 permeability, 93% FRR, and 97.3% dye rejection. Consequently, embedding functionalized MWCNT in the PVDF membrane matrix was led to improvement of membrane characteristics and enhancement of pure water flux, antifouling feature, and dye separation. So, the functionalized MWCNT could be a promising additive for the PVDF membrane modification.