Amino-functionalized Carbon Nanotubes Research Articles

Evaluation of properties of polymer concrete based on epoxy resin and functionalized carbon nanotubes

The objective of this research was to fabricate polymeric concretes comprising combinations of epoxy resin, aggregates, and amino-functionalized carbon nanotubes and to evaluate their properties. Polymeric concrete containing unfunctionalized carbon nanotubes (CNTs) was also studied. Thermogravimetric analysis demonstrated the efficiency of the functionalization of the CNTs, as well as the thermal properties of the resin/CNT nanocomposites. The inclusion of CNTs in the polymeric concrete led to a reduced curing time and improved mechanical properties compared to the reference polymeric concrete. A higher compressive strength was obtained with functionalized CNTs than with unfunctionalized nanotubes and to nanocomposites with low CNTs contents. This was attributed to chemical interactions between the resin and the CNTs that promoted a well-dispersed CNTs/matrix.

Poly(amidoamine) dendrimer-grafted carbon nanotubes as a hybrid multifunctional curing agent for epoxy-modified polyurethane

Carbon nanotube (CNT) grafted with hyperbranched poly(amidoamine) (PAMAM) dendrimer (CNTD) were used as a multifunctional curing and composite agent of polyurethane (PU) terminated with epoxy units. Amino-functionalized CNT was used as the core for grafting the first generation of PAMAM dendrimer by sequential addition of methyl acrylate and ethylenediamine. Two different epoxy-terminated PUs (PUB and PU-PMDA) were prepared from the reaction of poly(ethylene glycol), excess amounts of hexamethylene diisocyanate, and different chain extenders (1,4-butanediol for PUB and pyromellitic dianhydride (PMDA) for PU-PMDA), and subsequent end group transformation of the isocyanate groups to epoxy functionalities using glycidol. Fourier transform infrared spectra and thermogravimetric analysis (TGA) results showed that CNTD was successfully prepared. TGA thermograms revealed that thermal decomposition of composites were carried out in two main steps related to the soft and hard segments. In addition, char content and thermal stability of the composites were increased with increasing the CNTD content. Most importantly, the PMDA chain extender resulted in high thermal stability of the epoxy-terminated PU composites. X-ray diffraction and scanning and transmission electron microscopies presented morphological and structural properties of nanotubes and hybrid composites.

Exceedingly Rapid Enrichment of Organochlorine Pollutants in Complex Samples Using Amino-Functionalized Carbon Nanotubes

Organochlorine pesticides have made a large contribution to the development of modern agriculture but also caused contamination in the environment, and they persistently cause harm to humans and or...

Electrochemical sensor based on covalent organic frameworks-MWCNT-NH2/AuNPs for simultaneous detection of dopamine and uric acid

An electrochemical sensing platform for simultaneous determination of dopamine (DA) and uric acid (UA) is constructed based on covalent organic framework materials (IL COF-1), aminofunctionalized carbon nanotubes (MWCNT-NH2), and gold nanoparticles (AuNPs). The prepared sensor shows a good performance in detection of DA and UA due to porosity, large specific surface area, high conductivity and more active sites of the composite modified material. Under optimized experimental conditions, the constructed electrochemical sensor has sensitive response and good linearity to both DA and UA. Their wide linear ranges are 0.7–108 μM and 0.97–200 μM, and the detection limits are 0.21 μM and 0.29 μM (S/N = 3), respectively. The developed method has been successfully employed to determine the contents of DA and UA in dopamine injection and human urine samples. It has a satisfactory recovery rate, and the relative standard deviations (RSD) of three parallel determinations are all below 5.0%. In comparison, the constructed sensor platform has superior performance including low cost, simple structure, wide linear range and high sensitivity than some traditional methods, which is expected to be widely used in real sample analysis.

Amino functionalized carbon nanotubes supported CoNi@CoO–NiO core/shell nanoparticles as highly efficient bifunctional catalyst for rechargeable Zn-air batteries

Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are the core reaction processes of rechargeable Zn-air battery (ZAB) cathode. Therefore, exploring a bifunctional catalyst with excellent electrochemical performance, high durability, and low cost is essential for rechargeable ZAB. In this work, amino functionalized carbon nanotubes supported core/shell nanoparticles composed of CoNi alloy core and CoO–NiO shell (CoNi@CoO–NiO/NH2-CNTs-1) is synthesized through a simple and efficient hydrothermal reaction and calcination method, which shows higher ORR/OER bifunctional catalytic performance than the single metal-based catalyst, such as Ni@NiO/NH2-CNTs and Co@CoO/NH2-CNTs. The fabricated bimetallic alloy based catalyst CoNi@CoO–NiO/NH2-CNTs-3 with the optimized loading content of CoNi@CoO–NiO core/shell nanoparticles, presents the best bifunctional catalytic performance for ORR/OER. Experimental studies reveal that CoNi@CoO–NiO/NH2-CNTs-3 exhibits the onset potential of 0.956 V and 1.423 V vs. RHE for ORR and OER, respectively. It also exhibits a low overpotential of 377 mV to achieve a 10 mA cm−2 current density for OER, and positive half-wave potentials of 0.794 V for ORR. And the potential difference between half-wave potential of ORR (E1/2) and the potential at 10 mA cm−2 for OER (Ej10) is 0.813 V. In addition, when CoNi@CoO–NiO/NH2-CNTs-3 is used as an air electrode catalyst of rechargeable ZAB, its maximum power density and open circuit voltage (OCV) can reach 128.7 mW cm−2 and 1.458 V (The commercially available catalyst of Pt/C–RuO2 is 88.1 mW cm−2), which strongly demonstrates that the fabricated catalyst CoNi@CoO–NiO/NH2-CNTs-3 can be used as a highly efficient bifunctional catalyst for ZABs, and is expected to replace those expensive precious metal electrocatalysts to meet the growing demand for new energy devices.

Effects of hydroxyl, carboxyl, and amino functionalized carbon nanotubes on the functional diversity of microbial community in riverine sediment

Nowadays, more and more attention is focused on the environmental harm brought by the wide production and use of carbon nanotubes. In this study, the metabolic function of sediment microbial community was investigated after unfunctionalized or functionalized multi-walled carbon nanotubes (MWCNTs) were incorporated. The surface functional groups on the studied functionalized MWCNTs in this work were hydroxyl, carboxyl, and amino, respectively. The metabolic functional diversity was determined by Biolog EcoPlates after one-month exposure to MWCNTs. Incorporating 0.5 wt% amino functionalized MWCNTs significantly decreased the microbial activity and diversity, and all types of MWCNTs caused great inhibition on the microbial metabolism at the dosage of 2.0 wt%. The sediment microbes preferred polymers and amino acids. Principal component and similarity analysis indicated that the microbial carbon metabolism was more affected by the MWCNT dosage compared with the functionalization, and 2.0 wt% amino functionalized MWCNTs made the greatest difference in metabolic function of sediment microbial community. These consequences may help to assess the environmental risks of MWCNTs from the aspect of ecological relevance of sediment microbial community.

Efficient Carbon Dioxide Electroreduction over Ultrathin Covalent Organic Framework Nanolayers with Isolated Cobalt Porphyrin Units.

Electrochemical CO2 reduction represents a sustainable approach for the conversion of CO2 into valuable fuels and chemicals. Here, we fabricated a series of composite nanomaterials through template-oriented polymerization of covalent organic frameworks (COFs) with isolated cobalt porphyrin units on amino-functionalized carbon nanotubes for efficient electrocatalytic CO2 reduction reaction (CO2RR). Compared with pure COFs, the hybrid form of ultrathin COF nanolayers wrapped on the conductive scaffold leads to distended current density and stable Faradaic efficiency for CO2-to-CO conversion over a wide potential range. Specifically, the catalytic performances of the system can be finely optimized by the modification of the reticular structure with different functional groups. Our work gives a new strategy for the preparation of highly active and selective electrocatalysts for CO2RR.

Three-dimensional electrochemical sensor with covalent organic framework decorated carbon nanotubes signal amplification for the detection of furazolidone

In this study, we developed a facile one-pot strategy for immobilizing a covalent organic framework (COF) on an amino-functionalized carbon nanotube (NH2-CNT) support at room temperature. The COF@NH2-CNT composite obtained possessed a high specific surface area (147.3 m2 g−1), and good conductivity when deposited on the glassy carbon electrode (GCE). The COF@NH2-CNT/GCE sensor offered excellent analytical performance for the detection of the nitrofuran antibacterial agent furazolidone. The sensor offered a wide range furazolidone detection range from 0.2 μM to 100 μM, with a low limit of detection of 7.75 × 10-8 M. The recovery test was performed in chicken and lamb samples with satisfactory recoveries ranged from 87.8%–126.9%. The furazolidone residues in beef and pork samples were determined using the COF@NH2-CNT/GCE sensor and high-performance liquid chromatography. There was no significant difference between the two methods. The ability of the COF to efficiently adsorb furazolidone was a key to high sensitivity and fast response of the sensor platform. Results encourage the wider use of COFs in electrochemical sensor development.

An ultrasensitive fire-warning chitosan/montmorillonite/carbon nanotube composite aerogel with high fire-resistance

High fire-safe aerogel with multi-functionality is urgently desirable due to the frequent fire disasters. However, it is still a challenge to afford both excellent flame retardancy and sensitive fire-warning in combustible aerogels. Herein, we fabricated an ultrasensitive fire-warning and high fire-resistance chitosan/montmorillonite/carbon nanotube composite aerogel (CCA) via freeze-drying. Benefiting from the rapid decrease of the electrical resistance for amino-functionalized carbon nanotube when being burned, CCA achieved a hitherto shortest fire-warning response time (~0.25 s). Importantly, the aerogel exhibited excellent flame retardancy and self-extinguished in the vertical burning test. Besides, owing to the hierarchical porous structure of the aerogel and the excellent barrier effect of the montmorillonite nanosheet, CCA could resist a high-temperature flame up to 1200 °C and effectively prevent the temperature of the nonexposed side from increasing, exhibiting excellent thermal insulation. Furthermore, the mechanical resilience, anti-fatigue performance, electrical conductivity, and unique three-dimensional network endowed the aerogel with good piezoresistivity. This work provides a facile, environmentally-friendly, and cost-effective approach to fabricating multifunctional fire-safe aerogel, showing promising applications in exterior wall insulation, vehicle interior, firefighting, and wearable electronics.

Mechanically strong and tough polyimide aerogels cross-linked with amine functionalized carbon nanotubes synthesized by fluorine displacement reaction

Polyimide aerogels generally face problems of shrinkage and collapse of pore structure during preparation, resulting in poor macro-structural integrity and mechanical properties. Towards these problems, polyimide composite aerogels with three-dimensional porous network structure, outstanding mechanical and thermal properties have been synthesized by utilizing high grafting ratio of amino-functionalized carbon nanotubes (CNTs) prepared by fluorine displacement reaction in this study. All aerogel samples exhibited the network structure composed of highly interconnected nanofibers. Most importantly, the compression modulus of the PI aerogel reached to 47.3 MPa with the addition of amino-functionalized CNTs, which was 1126% higher than that of the linear PI aerogel. The prepared PI/CNT-NH2 composite aerogels can still maintain the original compressive modulus of 96% under high temperature conditions. These results indicate that the PI composite aerogels could exhibit great potential in aerospace applications as high-performance and lightweight porous materials.

Carbon nanotube-mediated antibody-free suspension array for determination of typical endocrine-disrupting chemicals.

Acarbon nanotube (CNT)-mediated antibody-free suspension array (CASA) by integration of functionalized CNTs and aptamer (Apt) into xMAP® technology for simultaneous determination of typical endocrine-disrupting chemicals(EDCs) was developed. The interaction between CNTs and Apt acts as an effective and straightforward signal recognition, transformation, and amplification strategy. The amino-functionalized CNTs are covalently modified on the carboxyl-functionalized magnetic bead (MB) and further physically bridging with biotinylated Apt. CNTs on the surface of MBs not only increase the amount of Apt for target binding andsignal amplification but also maintain the biological activity of Apt. After magnetic separation, the encoded MB address was distinguished and the concentration of the target in the liquid was negatively correlated with median fluorescence intensity. A series of environmental water samples were analysed by CASA, traditional immuno-SA, and competitive inhibition enzyme-linked immunosorbent assay for validation. The results obtained using CASA well matched for the multiplexed detection of various targets with dynamic concentrationrange from 6.40 × 10-5 to 4.00μgL-1 within 1h. The method also confirmed good selectively, accuracy, and consistency with high-performance liquid chromatography. Graphical abstractSchematic representation of amino-functionalized carbon nanotube (CNT)-bridged antibody-free suspension array for detecting of three typical endocrine-disrupting chemicals. The amino-functionalized CNTs are covalently modified and further physically interacted with biotinylated aptamer featuring in the recognition and binding with the target of interest.

The effects of functionalization of carbon nanotubes on toxicological parameters in mice.

Carbon nanotubes (CNTs) have emerged as a new class of multifunctional nanoparticles in biomedicine, but their multiple in vivo effects remain unclear. Also, the impact of various functionalization types and duration of exposures are still unidentified. Herein, we report a complete toxicological study to evaluate the effects of single- and multiwalled carbon nanotubes (SWCNTs and MWCNTs) with either amine or carboxylic acid (COOH) surface functional groups. The results showed that significant oxidative stress and the subsequent cell apoptosis could be resulted in both acute and, mainly, in chronic intravenous administrations. Also, male reproductive parameters were altered during these exposures. The amino-functionalized CNTs had more toxic properties compared with the COOH functionalized group, and also, in some groups, the multiwalled nanotubes were more active in eliciting cytotoxicity than the single-walled nanotubes. Interestingly, the SWCNTs-COOH had the least alterations in most of the parameters. Evidently, it is concluded that the toxicity of CNTs in specific organs can be minimized through particular surface functionalizations.

Amino functionalized carbon nanotubes as hole transport layer for high performance polymer solar cells

In this work, we demonstrated the synthesis of amino functionalized MWNTs (af-MWNTs) via a simple and facile hydrothermal process and the af-MWNTs was acted as the hole transport layers (HTLs) of polymer solar cells (PSCs) based on active layers of Poly[N‑9″‑hepta‑decanyl‑2,7‑carbazolealt‑5,5‑(4′,7′‑di‑2‑thienyl‑2′,1′,3′‑benzothiadiazole)] (PCDTBT) and fullerene derivative [6,6]‑phenyl‑C71‑butyric acid methylester (PC71BM). Comparing with the control devices, devices based on af-MWNTs HLTs achieved an optimal power conversion efficiency (PCE) of 6.970%, leading to 17.6% enhancement comparing to the control device. The af-MWNTs HTLs exhibited remarkable enhancement on electrical conductivity, which was beneficial to the hole extraction and transport on interface. The enhancement of PCE was mainly attributed to the superior hole transport and extraction capabilities. Meanwhile, the af-MWNTs exhibited a suitable work function (WF) which was beneficial to hole extraction from the photoactive layer to the ITO anode. The experimental results indicated that the af-MWNTs HTLs not only presented excellent optical and electrical properties, but also played an important role for improving the efficiency of PSCs.

Synthesis of Amino-functionalized Carbon Nanotubes and their Applications

Synthesis of Amino-functionalized Carbon Nanotubes and their Applications

Cross-linked graphene/carbon nanotube networks with polydopamine “glue” for flexible supercapacitors

Abstract Three-dimensional (3D) graphene-based composites can possess exceptional electrochemical performance owing to their unique structure and properties. Herein, a 3D cross-linked hierarchical porous polydopamine (PDA) modified reduced graphene oxide (rGO)/amino functionalized carbon nanotube (CNT-NH 2 ) composites were synthesized via hydrothermal method . The hierarchical electrode incorporates the advantages of 1D nanotube for effective charge transport, 2D graphene nanosheet for fast ion transport and 3D cross-linked hierarchical porous substrate for mechanical stability and flexibility. Attributing to these characters, the obtained rGO/CNT-NH 2/PDA (GCP) electrode presents a high capacitance (176.2 F g-1 at 0.5 A g-1 ) in aqueous 6.0 M KOH electrolyte. Symmetric supercapacitor based on GCP-50 electrodes exhibits a high energy density of 4.22 Wh kg -1 and excellent cycling stability with 98.9% capacitance retention after 10,000 cycles. Furthermore, the supercapacitors show superior flexibility and stability. The facile synthesis, promising electrochemical results and 3D hierarchical porous nanostructure of GCPs present potential for supercapacitor and other energy storage applications.

Interfacially reinforced unsaturated polyester carbon fiber composites with a vinyl ester-carbon nanotubes sizing agent

A amino-functionalized carbon nanotubes (CNTs)-containing sizing agent was prepared for improving the interface bonding and impact toughness of carbon fibers (CFs) reinforced unsaturated polyester (UP) composites. More reactive groups and better interfacial compatibility with UP make vinyl resin M7270 a more suitable polymer for preparing sizing agent for CF/UP composites when compared to epoxy, MR13006 and R806. The surface characteristics of CFs and the interfacial properties of the composites before and after surface modification were investigated. The observed uniformly dispersed CNTs-containing sizing agent on the CF surface obviously increased the surface roughness. The amount of polar functional groups and the wettability of CFs were significantly enhanced after the coating treatment. The interlaminar shear strength (ILSS) and impact toughness were enhanced by 32.3 and 55.2%, respectively. The sizing agent effectively enhanced the interfacial adhesion by improving the surface energy, and increasing chemical bonding and mechanical interlocking.

Ag nanoparticles-decorated nitrogen-fluorine co-doped monolayer MoS2 nanosheet for highly sensitive electrochemical sensing of organophosphorus pesticides

Two-dimensional (2D) MoS2 shows great potential in the areas of electrochemical sensors due to their ultrathin structure and predominant physicochemical properties. However, pristine 2D MoS2 nanostructure exists inherent disadvantages such as the limited electrical conductivity, surface area and easy aggregation or restacking. Here, nitrogen-fluorine co-doped monolayer 2D MoS2 nanosheet decorated with Ag nanoparticles (Ag NPs-N-F-MoS2) nanocomposite is prepared and it exhibits superior conductivity, remarkable electron mobility and high electroactive surface area. The obtained Ag NPs-N-F-MoS2 are employed as a sensing platform for the electrochemical determination of organophosphate pesticide, coupled with enzymatic inhibition. Under optimized conditions, the acetylcholinesterase (AChE)/amino functionalized carbon nanotubes (CNTs-NH2)/Ag NPs-N-F-MoS2 bioelectrode is superior in sensing performances for the detection of monocrotophos and chlorpyrifos, with wide linear ranges, low detection limit as low as 0.05 pg mL−1 (0.2 pM) and 1 pg mL−1 (3 pM) at a signal-to-noise ratio of 3, satisfactory selectivity, reproducibility and long-time storage stability. All results indicate that the Ag NPs-N-F-MoS2 nanocomposite holds great promise for constructing an ultra-sensitive electrochemical sensing interface for the determination of pesticides.

A sandwich-type electrochemical immunoassay for ultrasensitive detection of non-small cell lung cancer biomarker CYFRA21-1

Many studies confirm that the aberrant expression of Cytokeratin 19 fragment 21-1 (CYFRA21-1) is highly correlated with non-small cell lung cancer (NSCLC), especially for squamous cell carcinoma. Herein, we report a sandwich-type electrochemical immunosensor based on signal amplification strategy of multiple nanocomposites to test CYFRA21-1 selectively and sensitively. The proposed immunosensor fabricated by three-dimensional graphene (3D–G), chitosan (CS) and glutaraldehyde (GA) composite on the glass carbon electrode (GCE) with a large surface area is prepared to immobilize primary antibodies (Ab1) and provide excellent conductivity. To further amplify the electrochemical signal, the trace tag on the foundation of gold nanoparticles (AuNPs) is coated with amino-functionalized carbon nanotube (MWCNT-NH2) nanocomposite through thionine linking, which provides more amino groups to capture more horseradish peroxidase-labeled antibodies (HPR-Ab2) and enhances the conductivity. Under optimal conditions, the developed immunosensor exhibits excellent analytical performance for the determination of CYFRA21-1 with a wide linear range from 0.1 to 150ng·mL−1 and a low detection limit (LOD) of 43pg·mL−1. Furthermore, satisfactory results are obtained for the determination of CYFRA21-1 in real clinical serum samples, indicating the potential of the immunoassay to be applied in clinical analysis.

Effects of Amino-Functionalized Carbon Nanotubes on the Crystal Structure and Thermal Properties of Polyacrylonitrile Homopolymer Microspheres.

Amino-functionalized multi-walled carbon nanotube (amino-CNT)/polyacrylonitrile (PAN) microspheres with diameter of about 300–400 nm were prepared by in situ polymerization under aqueous solution. The morphology, crystal structure, and thermal properties of amino-CNTs on a PAN homopolymer were investigated by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, X-ray diffraction, and differential scanning calorimetry. The results showed that the amino-CNTs had a significant influence on the morphology of microspheres, and the PAN matrix were grafted onto the surface of amino-CNTs with interfacial bonding between them. The XRD studies showed that the crystal size of amino-CNT/PAN microspheres with lower crystallinity was bigger than in the control PAN homopolymer. The analysis of thermal properties indicated that the amino-CNT/PAN microspheres with lower glass transition temperature had a lower initial temperature and velocity of evolving heat during the exothermic processing as compared with the PAN homopolymer. These results suggested that the incorporation of amino-CNTs into the PAN homopolymer matrix was beneficial for controlling the heat released during the stabilization processing.

Effect of Processing Conditions on the Mechanical Behavior of Amino Functionalized Nanotube Modified Glass Fiber Epoxy Composites

In the present study ply glass fiber epoxy composites were prepared with amino functionalized carbon nanotubes using Vacuum assisted resin infusion molding VARIM technique The focus is to evaluate the different processing techniques used to uniformly disperse nanotubes in resin and their effect on mechanical properties In addition the dispersion and mechanical performance by incorporating amino nanotubes in curing agent vis agrave vis epoxy resin is also studied Lastly the mechanical behavior of composites on increasing the resin infusion temperature prior to its fabrication is also investigated The mechanical results along with SEM and TEM images validate the proposed processing methodology and use of higher infusion temperature