Functionalization Of Multi-walled Carbon Nanotubes Research Articles

Electrical Conductivity and Compressive Strength of Cement Paste with Multiwalled Carbon Nanotubes and Graphene Nanoplatelets

Many studies have been conducted using carbon-based nanomaterials (CBNs) for improving the electrical conductivity and mechanical properties of cementitious composites, but their practical use is yet to be achieved. Several methods have been attempted to secure the dispersibility in the cementitious composite matrix of CBNs, such as multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs). In this study, MWCNTs and GNPs were noncovalently functionalized using melamine, a low-cost chemical, and ball milling, a simple process commonly used in industrial fields. Additionally, MWCNTs and GNPs having one- and two-dimensional shapes were mixed with the cement paste to examine their effect on electrical conductivity and compressive strength. Following the experiment, it was shown that the electrical conductivity was improved via the noncovalent functionalization of MWCNT and GNP. The compressive strength increased up to approximately 0.30–0.60% of the CBNs content; however, for CBN content higher than 0.60%, the compressive strength decreased. The hybrid MWCNT and GNP mixture had a negligible effect on the electrical conductivity and compressive strength.

Synthesis of Water-Soluble Cadmium Selenide/Zinc Sulfide Quantum Dots on Functionalized Multiwalled Carbon Nanotubes for Efficient Covalent Synergism in Determining Environmental Hazardous Phenolic Compounds

Increasing pollution and ecological imbalance have accentuated the need to develop sensors through an efficient technique. Typically, the core–shell nanocrystals of cadmium selenide/zinc sulfide (CdSe/ZnS) with functionalized multiwalled carbon nanotubes (f-MWCNTs) are used for developing an efficient electrochemical sensor that simultaneously detects 4-aminophenol (4-AP) and 4-nitrophenol (4-NP). The composite network formed by CdSe/ZnS quantum dots with the f-MWCNTs (CdSe/ZnS QDs @ f-MWCNT) behaves as an excellent electrocatalyst and provides a transportation pathway by engendering the electron–hole pair. The sensor exhibits low detection limit values of 34.8 and 17.7 nM for detection of 4-AP and 4-NP, respectively. The sensor also showed excellent sensitivity at a linear working range of 0.149–510 μM concentration for both the analytes. Additionally, the study also shows the potential for commercial feasibility of the as-prepared sensor by acquiring a satisfactory recovery percentage of the analytes in real-time biological and environmental sample analyses.

Polyurethane polystyrene based smart interpenetrating network with quick shape recovery through thermal actuation

Polyurethane (PU), designed with pre-polymer method involving polyol as cross-linker, has been utilized for shape memory applications. Neat PU or PU-PS (polystyrene) interpenetrating network (IPN) samples have been prepared. Functionalized multiwall carbon nanotubes (FMWCNTs) have been utilized as reinforcements. PU composites have been studied for shape recovery time and found better than neat PU. 1wt% incorporation of FMWCNTs in PU has reduced shape recovery time to 22 s for 100% shape recovery, in comparison to neat PU with 62 s of 100% shape recovery. PU-PS IPN has reduced 100% shape recovery time to 17s. Superior hydrogen bonding in neat PU has been suggested as per longer shape recovery time against thermal actuation, in comparison to PU composite and IPNs with FMWCNTs. Decreased thermal stability has been observed with FMWCNTs incorporation, indicating enhanced heat dissipation. Field emission scanning electron microscopy analyses confirmed the difference of morphologies in neat PU, PU composite, and IPNs. A distinctive filler-matrix interaction in IPNs has been observed. XRD confirmed the presence of amorphous component. Rutherford Backscattering Spectrometry and Thermal Gravimetric Analysis have been utilized for analyses. Shape recovery study has been made by a simple experimental set up prepared in lab.

Влияние обработки в He:O плазме на структуру многостенных углеродных нанотрубок

The functionalization of multi-walled carbon nanotubes in He:O plasma is investigated. It's shown that plasma treatment leads to the removal of defective outer graphene layers and their fragments due to oxidation. It is established that the surface of functionalized multi-walled carbon nanotubes contains numerous uncoordinated carbon atoms and oxygen-containing functional groups. The preservation of the structure of the internal graphene layers of nanotubes and the formation of broken chemical bonds ensures a decrease in electrical resistance. At the same time, there is a narrowing of the distribution of electrical resistance values of nanotube ensembles.

Functionalization of multi-walled carbon nanotube (MWCNT) with CTACe surfactant and polyethylene glycol as potential drug carrier

Multi-walled Carbon Nanotube (MWCNT) pure is easy to form aggregate, making it difficult to apply as a drug carrier since it can be toxic to the body. It can be overcome by functionalization using surfactants, like cetyltrimethyl ammonium trichloro-monobromo-cerate (CTACe) and polyethylene glycol (PEG). First, MWCNT was functionalized with CTACe surfactant, then further PEG 6000 was used with several MWCNT-CTACe ratios. The functionalization was conducted under ultrasonic treatment, then followed by filtration, washing, and drying. The functionalized MWCNT underwent dispersion tests using water and dimethyl sulfoxide (DMSO) as the solvents. A dispersion test with water solvent shows that the functionalized MWCNT still forms aggregates within a few minutes. Whereas, in DMSO solvent, the functionalized MWCNT can be stabilized for more than five days without forming aggregates. FTIR results show a new peak at 1105 cm−1 and an increased peak intensity around 3432 cm−1, corresponding to C-N and hydrogen bonding of N-H vibration from the CTACe. The FTIR from PEG addition shows an increase in the wavenumbers around 3432,87 cm−1, indicating the strength of O-H/N-H intermolecular hydrogen interactions of O-H PEG with N-H surfactant ether bonds.

DIC analysis of nano concrete using functionalized and dispersed carbon nanotubes

Digital Image Correlation (DIC) method is considered as a powerful tool to capture material behavior for improved precision. This paper deals with effect of dispersion and functionalization of multiwall carbon nanotubes (MWCNTs) on fracture mechanics properties such as fracture energy and stress intensity factor. Fracture mechanics properties were found out using DIC technique and also by experimentally using a clip gauge and linear variable differential transformers (LVDT). The experiment was conducted under crack mouth opening displacement (CMOD) controlled manner and rate of loading was set as 0.0005 mm/s. MWCNTs were taken in a proportion of 0.1%, 0.2%, 0.3%, 0.4% and 0.5% by weight of cement and Nano silica and Nano alumina were considered as 3% and 2% by weight of cement respectively. The compressive strength is increased by 45.28% and tensile strength and flexural strength increased by108.26% and 53.249% respectively. It was seen that displacements measured by DIC and by experimentally were in the same line and also Load vs CMOD graphs plotted with both the methods are having similar behavior. Size effect was considered for preparation of all the specimens and by the results it can be seen that all specimens follow Bazant’s Size effect law.

The effect of He : O plasma treatment on the structure of multi-walled carbon nanotubes

The functionalization of multi-walled carbon nanotubes in He : O plasma is investigated. It is shown that plasma treatment leads to the removal of defective outer graphene layers and their fragments due to oxidation. It is established that the surface of functionalized multi-walled carbon nanotubes contains numerous uncoordinated carbon atoms and oxygen-containing functional groups. The preservation of the structure of the internal graphene layers of nanotubes and the formation of broken chemical bonds ensure a decrease in electrical resistance. At the same time, there is a narrowing of the distribution of electrical resistance values of nanotube ensembles. Keywords: multi-walled carbon nanotubes, plasma treating, functionalization, transmission electron microscopy, X-ray photoelectron spectroscopy

Design of an efficient, tunable and scalable freestanding flexible membrane for filter application.

To address the global challenge of water pollution, membrane-based technologies are being used as a dignified separation technology. However, designing low-cost, reusable, freestanding and flexible membranes for wastewater treatment with tunable pore size, good mechanical strength, and high separation efficiency is still a major challenge. Herein, we report the development of a scalable, reusable, freestanding, flexible and functionalized multiwalled carbon nanotube (FMWCNT) membrane filter with tunable pore size for wastewater treatment, which has attractive attributes such as high separation efficiency (>99% for organic dyes and ∼80% for salts), permeance (∼225 L h−1 m−2 bar−1), tensile strength (∼6 MPa), and reusability of both the membrane as well as contaminants separately. This FMWCNTs membrane filter has been developed by a simple vacuum-assisted filtration technique followed by the synthesis of MWCNTs using a cost-effective spray pyrolysis assisted chemical vapor deposition (CVD) technique and chemical functionalization. This study deals with understanding the rejection, retrieval, and reusability of both the membranes as well as waterborne contaminants separately. The developed membrane filter has potential utility in many applications such as wastewater treatment, food industry, and life sciences due to its robust mechanical and separation performance characteristics.

Fabrication and Characterization of Functionalized Multi-Wall Carbon Nanotubes / Polysulfone Nanocomposite Membranes for Fouling Mitigation

Fabrication and Characterization of Functionalized Multi-Wall Carbon Nanotubes / Polysulfone Nanocomposite Membranes for Fouling Mitigation

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

Preparation of Antifouling and Antibacterial Polyvinylidene Fluoride Membrane by Incorporating Functionalized Multiwalled Carbon Nanotubes

Preparation of Antifouling and Antibacterial Polyvinylidene Fluoride Membrane by Incorporating Functionalized Multiwalled Carbon Nanotubes

Effect of baking, humidity and UV radiation on hexagonal boron nitride modified c-MWCNT nanohybrid electrodes

Electrically conducting nanohybrids (NHs) of hexagonal boron nitride (h-BN) with carboxylic functional multiwalled carbon nanotubes (c-MWCNT) have shown growing interest as electrode materials in microelectronics. This has been due to their ability to serve as potential electrically conducting materialsunder harsh environmental conditions of temperature, humidity and radiations. Present investigation demonstrates the development and characterisation of working electrodes (WEs) derived by coating of NHs and polyvinyl butyryl suspension in N-methyl-2-pyrrolidone (NMP) over stainless steel current collector. Field emission scanning electron microscopy (FESEM) and thermogravimetric analysis in air were used to examine the surface morphology and thermal stability of NHs. Effect of baking time (BT), humidity exposure (HE) and photo aging (PA) on functionality and performance of WEs has been investigated. The DC conductivity (σDC) of WEs increased somewhat with BT, reaching 0.97 upto 3 hr. Increasing BT to 6.0 hr resulted in a slight fall in the σDC of WEs to 0.94, which thereafter remained static at 0.92 at 9.0 hr. Under UV exposure for 3 hr, the σDC of WEs reached to 1.12. The σDC of WEs has been reduced to 0.99 after further 6 hr of irradiation and later it has reached to 0.98 after 9 hr of irradiation of WEs. The σDC of NHs under HE conditions was found in increasing order ranging from 0.96 to 1.14 for 0 to 3 hr and further marginal reduction from 1.11 to 1.10 for 6 to 9 hr.

Preparation of Antifouling and Antibacterial Polyvinylidene Fluoride Membrane by Incorporating Functionalized Multiwalled Carbon Nanotubes

Preparation of Antifouling and Antibacterial Polyvinylidene Fluoride Membrane by Incorporating Functionalized Multiwalled Carbon Nanotubes

Qualitative study on the effects of hydroxyl functionalized multiwall carbon nanotube and silica doped‐epoxy composites

AbstractEpoxy resins have great potential for industrial applications because of their excellent properties such as good adhesion, durability, higher strength, and so forth. But, their high‐viscosity limits industrial usage. Reducing the viscosity with suitable diluents provides an advantage on industrial scale processing, but this also causes a decrease in their chemical and mechanical properties. The production of epoxy‐based composite materials provides good mechanical, heat, and solvent resistance properties. Therefore, determination of additives amount and dilution ratio for specific working area are important for these materials. In this context, this study first includes synthesis of bisphenol A‐based epoxy resin and characterization with fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Second, chemical, mechanical, thermal, and surface properties of the resin were investigated by varying the reactive/nonreactive diluents and additives. Multiwall carbon nanotube (MWCNT‐modified with triton X‐405 nonionic surfactant) and fumed silica as additives were used in this study. Mechanical and chemical tests were applied to 49 types of materials. In order to see the significance levels and synergistic effects of diluents on tensile strength, 3D graphs were obtained with the experimental and modeled data. ANOVA was also performed for significance levels of the diluents. After that, the effects of silica and carbon nanotube additive on tensile strength were investigated. As a result of the tensile test and TGA analysis of the pure epoxy, the ultimate tensile strength was measured as 59.07 MPa, Tg (°C), and Tm (°C) values were found as 175.5 and 304.0°C. These results increased for the nanocomposite material prepared with 2% fumed silica and 0.1% MWCNT (modified YAM) as 81.64 MPa, 192.2 and 333.3°C. It was also shown that the ultimate tensile strength, which decreased with dilution of pure epoxy, could be increased significantly with the additives.

Shear performance of MWCNTs modified single-lap joints of glass/epoxy laminates

In this experimental work, the single lap joint (SLJ) adhesive strength of glass fibre reinforced epoxy (GFRP) composites was investigated under quasi-static tensile loading. The adhesive used was 'Araldite® adhesives-2015 (AA)'. Further, the functionalized multiwall carbon nanotubes (s-MWCNTs) were used to modify the AA. The s-MWCNTs were mixed in AA through the ultrasonication method at six weight ratios, i.e. 0, 0.25, 0.5, 0.75, 1 and 1.25 wt. %. Experimental results showed that among different weight fractions of s-MWCNTs modified AA, the 1 wt. % of s-MWCNTs reinforcement yielded a maximum bond strength and slip. The two-parameter Weibull statistical method proved that the results for increasing s-MWCNTs in AA were reliable up to 1 wt. % s-MWCNTs doping. Strain-field analysis at bond-edge by using digital image correlation (DIC) technique showed a significant variation with s-MWCNTs reinforcement in strain distributions at bonded edge-section. Fracture behaviour analysis at the macroscopic and microscopic proved that with the rise in uniformly distributed s-MWCNTs, bridging (or interlocking mechanism) occurs, which hindered the bond failure. Further, above the optimized value of s-MWCNTs reinforcement, i.e. 1.25 wt. % of s-MWCNTs in AA; an agglomeration of s-MWCNTs took place, reducing the bond performance.

Polylactic acid/multi walled carbon nanotubes (PLA/MWCNT) nanocomposite for 3D printing of medical devices

In recent years, the composite nanomaterials area has had a great development impact in health sciences. Biomaterials depict as one of the most promising since they are compatible with additive manufacturing (AM) techniques. It is also possible to use them to mold specific medical parts. Composite nanomaterials have shown good biocompatibility and low toxicity to have benefits equal to or greater than metals (i.e., Co-Cr alloy). The purpose of this study is to develop a nanocomposite biomaterial (PLA/MWCNTf) from Polylactic Acid (PLA) and functionalized Multi Walled Carbon Nanotubes (MWCNTf) to evidence its potential application in 3D printing of orthopedic fixation devices. PLA/MWCNTf nanocomposite was prepared by solution blending technique, incorporating a proportion of 0.5 wt% of MWCNTf to the PLA matrix. TGA analysis of the PLA/MWCNTf was used to determine the thermal stability, a slight increase was found compared to the PLA. FTIR spectroscopy confirmed the presence of carboxylic acid groups in the MWCNTf which improves good incorporation of the nanotubes in the PLA matrix. Additionally, Raman spectroscopy, SEM, and AFM micrographs were used to verify MWCNTf reached the PLA surface homogeneously. Additive manufacturing preparation was done by extrusion molding of PLA/MWCNTf as well as its 3D printing.

Controlling the enrichment location of brush grafted multi-walled carbon nanotubes at the interface of various polymer blends

Guided by a phase diagram we proposed recently, the identical multi-walled carbon nanotubes (MWNTs) grafted with poly(methyl methacrylate) (PMMA) brush may be located at the interface of various PMMA-based blends. Hence, we grafted PMMA brushes with the molecular weight less than that of PMMA matrix roughly on the surface of MWNTs by Cu(0)-mediated living radical polymerization, in which DMF was selected as a good reaction solvent of MMA and proper dispersant of 2-bromoisobutyrate functional MWNTs. Such modified MWNTs can be mostly located at the interface of PMMA/styrene-acrylonitrile copolymer (SAN), PMMA/polystyrene (PS), PMMA/polyvinyl acetate (PVAc) and PMMA/poly(α-methyl styrene-co-acrylonitrile) (MSAN) blends. It can provide a path as a reference template to prepare various nanocomposites with nanoparticles self-assembling at the interface of binary polymer blends.

Amino Acid Functionalization of Multi-Walled Carbon Nanotubes for Enhanced Apatite Formation and Biocompatibility

Amino Acid Functionalization of Multi-Walled Carbon Nanotubes for Enhanced Apatite Formation and Biocompatibility

Effect of Functionalized Multi-Walled Carbon Nanotubes on Preparation of High Strength and Conductive Copper-CNTs Composites by Electrodeposition

Functionalized multiwalled carbon nanotubes (MWCNTs)-reinforced copper (Cu) composites were prepared by the combination of electrowinning and hot-pressing sintering and cold rolling process. The influence of the functionalization of MWCNTs on the strength and electrical properties of MWCNTs/Cu composites was studied. Functional group was introduced to increase the wetting of water electrolytes, improve the poor wettability of MWCNTs and form a highly active surface suitable for the preparation of MWCNTs/Cu composites by electro-deposition, enabling MWCNTs to be evenly dispersed in Cu matrix. Studies have shown that the addition of 1% of functionalized MWCNTs composite can increase the tensile strength by 6% and 165% compared with the addition of unfunctionalized and pure copper. It’s worth noting that the increase of oxygen-containing functional group brought about by functionalized MWCNTs did not significantly reduce the electrical properties of composites. The main reason for this is the good dispersion of the treated MWCNTs in Cu matrix and the bridging for electronic transmission, ensuring that the high electrical properties of MWCNTs/Cu composites are just slightly lower than those of electrolytic pure copper (99.92% IACS).

NahAa can convert naphthalene and reduce chromate simultaneously and immobilized on functional multiwall carbon nanotubes for wastewater treatment

Pseudomonas brassicacearum LZ-4 is a facultative anaerobic bacterium, can efficiently degrade naphthalene and reduce chromate simultaneously. In this study, we showed that the naphthalene degradation enzyme NahAa from P. brassicacearum LZ-4 can reduce Cr(VI). Heterologous expression in E. coli S17-1 along with RNA interference of NahAa in strain LZ-4 showed the enzyme can reduce chromate in vivo.In vitro, purified NahAa was identified and can catalyze Cr(VI) reduction by 64.2%. Flavin adenine dinucleotide (FAD) was identified as a cofactor of NahAa, which Cr(VI) could obtain electrons from NADH through NahAa-associated FAD for reduction. Immobilized NahAa on functional multi walled carbon nanotubes via physical adsorption method to produce a stable, high efficient composite MWCNT-NahAa. The maximum efficiency of MWCNT-NahAa composite was obtained in enzyme concentrations of 6 mg/mL and 20 min immobilization time. The optical reaction conditions for MWCNT-NahAa were pH 7.0 and 30 °C, still retaining 50% of its initial activities after five consecutive cycles. Application of composites in wastewater can reduce 90.4% Cr(VI), higher than free NahAa that was 63.5%. To our best knowledge, this is the first report immobilized enzyme in polycyclic aromatic hydrocarbons-degradation pathway for Cr(VI) wastewater treatment, providing a new insights on combined pollution remediation.