Polymer Nanotubes Research Articles

Carbendazim trace analysis in different samples by using nanostructured modified carbon paste electrode as voltametric sensor.

Carbendazim (CBZ) as a fungicide is widely used to control fungal diseases in agriculture, veterinary medicine, and forestry. In this study, molecularly imprinted nano-size polymer was synthesized and then combined with multiwalled carbon nanotubes to be used as modifiers for carbon paste electrode to detect carbendazim in water, fruit, agricultural wastewater, and urine samples by using the square-wave technique. Some common ions and pesticides were investigated as interferences in analyte, to study the sensitivity and selectivity of the modified carbon paste electrode for carbendazim. The combination of molecular imprinted polymer and multiwalled carbon nanotubes showed a significant increase in peak current in electrocatalytic activity on electrochemical detection of the carbendazim. The linear range of 1 × 10-10 to 5 × 10-8 molL-1 was investigated. The lower detection limit was determined to be 0.2 × 10-10 molL-1, and the relative standard deviation for the target molecule analysis was 2.07%. The result reveals that the modified carbon paste sensor with Multi walled Carbon Nanotubes (MWCNTs) and Molecular Imprinted Polymer (MIPs) can be used easily, without preparation steps that have high selectivity and sensitivity to determine carbendazim in water, fruit, agricultural wastewater, and urine samples.

Conductive and Self-Healing Carbon Nanotube–Polymer Composites for Mechanically Strong Smart Materials

It is a great challenge to develop polymeric materials possessing multiple functionalities for their intrinsic properties. In our efforts to overcome this dilemma, we report a carbon nanotube (CNT)-doped polymer architecture design in this paper using a soft matrix synthesized from methacrylic acid and poly(ethylene glycol) methacrylate via reversible addition–fragmentation chain-transfer polymerization and further functionalized by 1-pyrenemethanol and doped with hard, stiff CNTs as fillers. The CNTs were dispersed evenly into the pyrene-functionalized copolymers obtained via the solution blending method. Our approach is simple, low-energy-consuming, facile in operation, and highly efficient. The developed composites demonstrate high mechanical strength, self-healing ability, and high electrical conductivity. To further maximize the potential of our CNT-filled composites, we introduced a simple but effective means to align CNTs by directional stretching at elevated temperatures and so achieved significant mechanical and electrical reinforcement. The multifunctional composites produced in this paper have desirable properties for future applications such as conductive bioskins, healthcare monitoring sensors, and other functional conductive electronics.

Facile Construction of Three-Dimensional Architectures of a Nanostructured Polypyrrole on Carbon Nanotube Fibers and Their Effect on Supercapacitor Performance

Conducting polymer and carbon nanotube hybrids have been researched intensively in recent years for electrodes of fiber-shaped supercapacitors (FSSCs) toward flexible and wearable energy storage devices. Here, three-dimensional (3D) hierarchical polypyrrole (PPy)/carbon nanotube fiber (CNTF) architectures have been prepared by a facial electrodeposition method for flexible FSSC electrodes. PPy nanoparticles, vertically aligned nanowire arrays (VANAs), and nanowire networks were synthesized on CNTFs, respectively, to construct three types of 3D architectures by controlling the electrodeposition condition of PPy. The influence of the 3D architectures of PPy/CNTF electrodes on the performance of the assembled quasi-solid-state FSSCs has been carefully studied. The FSSCs with PPy VANAs showed a much higher specific capacitance than that with PPy nanoparticles because the hierarchical porous structure of PPy VANAs provides a higher accessibility of electrolytic ions and a higher Coulombic efficiency than that with the PPy nanowire network. The PPy VANA-/CNTF-based FSSCs displayed high flexibility, stability, and a specific capacitance of 178.14 F g–1 at 0.4 A g–1, which is much higher than that based on common PPy cauliflower-like film/CNTF electrodes (92.06 F g–1) and pure CNTF electrodes (8.48 F g–1) under the same conditions, demonstrating the great advantages of the 3D hierarchical structure.

Fabrication of novel fluorene incorporated conjugated microporous polymer nanotubes for visible-light CO2 reduction with water vapor

Two novel fluorene incorporated conjugated microporous polymer nanotubes are prepared by the template-free Sonogashira coupling reaction and exhibit attractive performance in gas-phase CO2 photoreduction.

Graphene oxide coated polyaminoanthraquinone@MXene based flexible film electrode for high-performance supercapacitor

The diversified development of electronic products stimulates the great demand for flexible energy storage devices with high energy density. Poly (1,5-diaminoanthraquinone) (PDAAQ) is considered as a highly promising electrode material due to its unique π-conjugated structure and high theoretical capacitance. Herein, we first prepare cetyltrimethylammonium bromide (CTAB) modified graphite oxide (GO) coated poly (1,5-diaminoanthraquinone) (PDAAQ) nanotubes@Ti3C2TX flexible film (CGO/PDAAQ@MXene) by electrostatic self-assembly. After modification with cationic surfactant, CTAB modified GO coated PDAAQ nanotubes (CGO/PDAAQ) exhibits overall positive charge, and then polymer nanotubes are uniformly inserted into negatively charged layered MXene to effectively avoid self-stacking of MXene layers. Under the synergistic effect, the ordered 1D nanotubes structure of CGO/PDAAQ and excellent intrinsic conductivity of MXene can greatly enhance the electron transfer and ion migration rates for electrode. The flexible self-supporting CGO/PDAAQ@MXene has good mechanical properties and can be completely recovered after 500 bending tests. Electrochemical tests of the flexible electrode exhibit the specific capacitance of 346 F g at 1 A g−1 (865 mF cm−2 at 2.5 mA cm−2), good rate performance and excellent cyclic stability. The as-fabricated flexible asymmetric supercapacitor exhibits high energy density of 41 Wh kg−1 at 404 W kg−1, which can successfully light 35 small LED bulbs.

Twisted and coiled yarns for energy harvesting and storage, artificial muscles, refrigeration, and sensing

This overview focuses on our teams work on using twisted yarns and highly elastic coiled yarns for artificial muscles, energy harvesting, energy storage, sensing, and refrigeration. Despite the diversity of these applications for coiled carbon nanotube and polymer yarns, similar fabrication methods are applicable and conversion of coiling twist to yarn twist results in yarn elasticity, actuation, twistocaloric cooling, and the capacitance changes used for energy harvesting and sensing. Likewise, the same biscrolling method yields coiled yarns containing up to 95 weight percent of guest powders that provide various new properties. The obtained performance of the coiled polymer and carbon nanotube yarns are remarkable, such as artificial muscles that generate up to 98 times the output mechanical power than the maximum for the same weight human muscle and mechanical energy harvesters providing a higher peak electrical power per weight than prior art material-based mechanical energy harvesters for stretch frequencies between a few Hz and 600 Hz.

Vertical alignment of carbon nanotubes in photo-curable polymer for multi-functional hybrid materials

Carbon nanotubes (CNTs) are nanomaterials with excellent mechanical strength, electric conductivity, and low weight. Interestingly, vertically aligned CNTs show much higher mechanical and electrical properties than randomly networked CNTs, because CNTs are much more resistant to axial impacts than lateral impacts; this study suggests an efficient process to produce vertically aligned multi-walled carbon nanotubes (VA-MWNT)-photocurable polymer hybrid materials. VA-MWNTs can fortify the mechanical properties of polymer composites even with very small amounts of MWNTs in the composite. Previous studies have produced VA-MWNT–polymer hybrid materials by coating polymers on MWNT forests synthesized in the vertical direction. However, this method cannot be extended to the large-scale production of hybrid polymers because of the limited area of substrates for the synthesis of the MWNT forests, and because the synthesis requires a complex and expensive process. We arranged MWNTs in the vertical direction in VA-MWNT-polymer mixtures in a short process via electrophoresis. Subsequently, UV irradiation for a few minutes completely cured the photocurable polymer while the MWNTs were fixed in the vertical direction. The VA-MWNT-polymer showed a 17% higher compressive force than the polymer itself and interestingly, a 49% higher compressive force than the polymer with randomly dispersed MWNTs, indicating that the orientation of MWNTs in polymer composites affects their curing behavior as well as mechanical strength. These polymer-MWNT composites can be used as-is or coated on other materials and can be expected to exhibit enhanced mechanical properties in various applications.

Elastomeric Core/Conductive Sheath Fibers for Tensile and Torsional Strain Sensors.

Motion sensing, aimed at detecting and monitoring mechanical deformation, has received significant attention in various industrial and research fields. In particular, fiber-structured mechanical strain sensors with carbon-based materials have emerged as promising alternatives for wearable applications owing to their wearability and adaptability to the human body. Various materials, structures, sensing mechanisms, and fabrication methods have been used to fabricate high-performance fiber strain sensors. Nevertheless, developing multi-modal strain sensors that can monitor multiple deformations remains to be accomplished. This study established core/sheath fiber multi-modal strain sensors using polymer and carbon nanotubes (CNTs). Specifically, a flexible and conductive CNT sheet was wrapped onto the elastomeric core fiber at a certain angle. This wrapping angle allowed the CNTs to mechanically deform under tensile and torsional deformations without fatal structural damage. The CNTs could sense both tensile and torsional strains through reversible structural changes during deformations. The fiber strain sensor exhibited an increase of 124.9% and 9.6% in the resistance during tensile and torsional deformations of 100% and 1250 rad/m, respectively.

Controllable construction of laser-induced colorful patterns based on thermal energy transfer between carbon nanotubes substrate and polymer interface

Laser irradiation technology has been widely used in the field of polymer material patterning. Improving the laser response of polymer is the key to realize laser patterning. The traditional doping process cannot achieve pattern colors other than black and white, and will affect the performance of polymer matrix. In this paper, the locally controllable laser-induced pattern transfer between the substrate and the polymer interface is realized by preparing a carbon nanotubes (CNTs) substrate with high photothermal conversion effect. The laser beam was irradiated on the interface between the CNTs substrate and the transparent polyvinyl alcohol (PVA) film. The CNTs substrate absorbed laser energy and transferred to PVA film to produce a carbonized pattern in situ. Further, colorful inorganic pigments can be transferred from the substrate to the polymer surface layer based on this interfacial transfer technique, which makes a breakthrough to realize the colorful laser-induced pattern of polymers. Moreover, the repeatability test further proves the reliability and recycling performance of the CNTs substrate. This study provides a positive approach for the industrialization of laser-induced colorful patterns on polymers.

Tunneling resistance model for piezoresistive carbon nanotube polymer composites

Carbon nanotube (CNT) polymer composites exhibit outstanding electrical conductivity that enables a myriad of sensing and actuation applications. Highly sensitive strain sensors can be realized through piezoresistivity in which a resistance change is induced by mechanical strains. Tunneling conduction between CNTs in close proximity is a major mechanism contributing to the overall piezoresistivity of the CNT network, and is sensitive to the separation distance, lattice registry and the orbital overlap of the interacting CNTs. In this paper, we propose a tunneling resistance model that relate these effects to the CNT chirality, geometry, and orientation. We construct the model based on the distance-dependent Landauer equation, and introduce two additional geometric variables, namely the lattice alignment angle and the axis alignment angle. The tunneling resistance model is incorporated into a CNT network representative volume element to determine the piezoresistivity of the CNT polymer composite. The model reproduces the periodic variation of tunneling resistance consistent with experimental observations and quantum simulations in the literature, and provides improved predictive accuracy of piezoresistivity in CNT polymer composites.

Coupled Newmark beta technique and GDQ method for energy harvesting and vibration control of the piezoelectric MEMS/NEMS subjected to a blast load

The controlled vibration and energy harvesting from a sandwich nanobeam, including two piezoelectric layers and a nanocomposite core, is investigated with the aid of nonlocal strain gradient theory. The nanobeam system is placed on an elastic substrate and under shockwave. The core layer is made of a reinforced composite made of a matrix polymer and carbon nanotubes (CNTs) along with carbon fibers (CF). The formulations along with end conditions are attained via Hamilton's principle and solved by the generalized differential quadrature method (GDQM) coupled with the Newmark beta method. Additionally, the vibration is controlled with two differential and integral gains. The impact of parameters such as elastic foundation, control gains, nonlocal factors, and parameters affecting the core material on forced vibration as well as energy harvesting is explored in detail. The current results are validated utilizing other publications. This work can be a basis for future studies on energy harvesting and controlled vibration on small scales.

Computational analysis of tunneling conduction in piezoresistive carbon nanotube polymer composites

Carbon nanotube polymer composites exhibit piezoresistivity that can be utilized for flexible strain sensors. Piezoresistive modeling is critical for improving sensor performance, but remains a challenging subject due to the complex CNT network microstructure and the various effects occurring at both the micro and nano scales. Tunneling conduction between CNTs is the primary mechanism underlying piezoresistivity in carbon nanotube polymer composites. Existing models have employed a myriad of assumptions on the CNT network kinematics and the tunneling conduction behavior, but their physical basis and effects have not been thoroughly studied. In this paper, a detailed evaluation on these modeling assumptions is presented with the goal of establishing an approach without ad hoc assumptions and improved predictive accuracy. A computational model that is capable of tracking the history of tunneling separation of each CNT junction is first constructed. The effects of CNT extensibility, tunneling cross-section, conduction channels are studied via statistical analysis of the tunneling conduction and comparison of computed piezoresistive response. It is found that CNT inextensibility leads to higher predicted piezoresistivity, the tunneling cross-section area in the Simmons approximation is a highly influential parameter, and the Landauer formula provides a more physically based approach that accounts for CNT properties.

Electrically Conductive Adhesive Based on Thermoplastic Hot Melt Copolyamide and Multi-Walled Carbon Nanotubes.

For the bonding of the lightweight composite parts, it is desired to apply electrically conductive adhesive to maintain the ability to shield electromagnetic interference. Among various solvent-based adhesives, there is a new group of thermoplastic hot melt adhesives that are easy to use, solidify quickly, and are environment-friendly. To make them electrically conductive, a copolyamide-based hot melt adhesive was mixed with 5 and 10 wt% of carbon nanotubes using a melt-blending process. Well-dispersed nanotubes, observed by a high-resolution scanning microscope, led to the formation of a percolated network at both concentrations. It resulted in the electrical conductivity of 3.38 S/m achieved for 10 wt% with a bonding strength of 4.8 MPa examined by a lap shear test. Compared to neat copolyamide, Young’s modulus increased up to 0.6 GPa and tensile strength up to 30.4 MPa. The carbon nanotubes improved the thermal stability of 20 °C and shifted the glass transition of 10 °C to a higher value. The very low viscosity of the neat adhesive increased about 5–6 orders of magnitude at both concentrations, even at elevated temperatures. With a simultaneous growth in storage and loss modulus this indicates the strong interactions between polymer and carbon nanotubes.

Analytical formulation of the piezoresistive behavior of carbon nanotube polymer nanocomposites: The effect of temperature on strain sensing performance

Carbon nanotubes (CNTs) are incorporated into a stretchable polymer to determine modified thermo-resistive and piezoresistive responses of a nanocomposite under temperature variation and mechanical strain. Monte Carlo simulation is paired with tunneling model to disperse CNTs into the representative volume element and recognize CNT-to-CNT separation distance to predict the resistance change of nanocomposites subjected to strain. The principle of thermo-electrical properties is studied under thermo-mechanical stimulus. Nanotube reorientation model is used to investigate the influence of CNT’s tunneling and state of alignment on the piezoresistive behavior of the nanocomposite. Comparisons between modeling results and experimental data suggested a good agreement. The nearly linear dependence of relative resistance change with strain displayed more sensitivity with shorter CNTs and less sensitivity with higher CNT volume fractions. Relative resistance change with temperature was strongly affected by CNTs’ temperature coefficient of resistance and volume fraction. Such change was more pronounced for the anisotropic nanocomposite.

Multiwalled Carbon Nanotubes Polylactide Composites for Electrical Engineering—Fabrication and Electrical Properties

In the article, both the processes of manufacturing highly homogeneous polylactide resin/multiwalled carbon nanotubes (CNTs) and their properties are described. Regarding the application of carbon nanotubes polymer composites, one of the most important problems to solve is obtaining good dispersion of the filler in the polymer matrix. Preparation of polylactide/multiwall CNTs composites by quick polymer solidification and freezing the state of the dispersion of the nanotubes in the polymer solution is described. The method we used employs an increase in viscosity (carried out rapidly) of the sonicated polymer solution containing the CNTs by spray deposition. Good dispersion of the nanotubes is confirmed by electron microscopy. The obtained nanocomposites exhibit a low percolation threshold for electrical conductivity (above 0.25% by weight). The described method leads to obtaining an electrical conductive surface on virtually any material and reduces the small amount of an expensive filler (CNTs) needed to achieve good electrical conductivity. Furthermore, the carbon nanotubes used in the fabrication process of the composites were obtained using the liquid-source chemical-vapor deposition (LSCVD) synthesis method.

A Short Review on: Recent Advances in the Use of Carbon Nanotubes in Additive Manufacturing of Polymer Matrix Composites

AbstractThe multi‐functionality of polymer matrix composites, proposes remarkable merits over metals including more stiffness and strength, lower weight, higher resistance to corrosion, and fatigue, etc. Furthermore, the next generation of production undergoes a revolution by increasingly progresses in additive manufacturing. There have been a large group of materials that can be exploited for this fashionable fabrication technique, although, polymer matrix composites are a significant class of material that have recently been used in additive manufacturing. The mixture of these polymers with nanofillers such as carbon nanotube improves mechanical, thermal, and electrical conductivity properties. This short review summarizes relevant production techniques, carbon nanotube polymer matrix composites, and performed research on its application for additive manufacturing.

Study of mechanical anisotropy of single walled carbon nanotube and polyvinyl alcohol polymer nanocomposite with a controlled alignment process

Study of mechanical anisotropy of single walled carbon nanotube and polyvinyl alcohol polymer nanocomposite with a controlled alignment process

Vertically Aligned Conductive Polymeric Nanotubes Grown on Percolated Multiwalled Carbon Nanotube Films for Supercapacitor Electrodes

Vertically Aligned Conductive Polymeric Nanotubes Grown on Percolated Multiwalled Carbon Nanotube Films for Supercapacitor Electrodes

Fabrication of a magnetic alginate-silk fibroin hydrogel, containing halloysite nanotubes as a novel nanocomposite for biological and hyperthermia applications

In this study, the main focus was on designing and synthesizing a novel magnetic nanobiocomposite and its application in hyperthermia cancer treatment. Regarding this aim, sodium alginate (SA) hydrogel with CaCl2 cross-linker formed and modified by silk fibroin (SF) natural polymer and halloysite nanotubes (HNTs), followed by in situ Fe3O4 magnetic nanoparticles preparation. No important differences were detected in red blood cells (RBCs) hemolysis, confirming the high blood compatibility of the treated erythrocytes with this nanobiocomposite. Moreover, the synthesized SA hydrogel/SF/HNTs/Fe3O4 nanobiocomposite does not demonstrate toxicity toward HEK293T normal cell line after 48 and 72 h. The anticancer property of SA hydrogel/SF/HNTs/Fe3O4 nanobiocomposites against breast cancer cell lines was corroborated. The magnetic saturation of the mentioned magnetic nanobiocomposite was 15.96 emu g−1. The specific absorption rate (SAR) was measured to be 22.3 W g−1 by applying an alternating magnetic field (AMF). This novel nanobiocomposite could perform efficiently in the magnetic fluid hyperthermia process, according to the obtained results.

Multi-functional and integrated actuators made with bio-inspired cobweb carbon nanotube–Polymer composites

Soft actuators have emerged as flexible platforms that can integrate many functional electronic devices to build intelligent electronic systems. The energy supply and wireless signal transmission of electronic systems of the multi-functional actuators are challenging research areas. Here, the idea of the functionalized and hierarchical design is proposed to construct the multi-functional and integrated actuators. Inspired by the structure of cobwebs, multi-functional carbon nanotube (CNT)-polymer composites with network structures are proposed and applied in multi-responsive actuators, supercapacitors, and electromagnetic interference (EMI) shielding devices. Two multi-functional and integrated actuators are highlighted to demonstrate the practical applications. One is a light-driven actuator integrated with an EMI shielding function, which can be used as an intelligent shielding curtain. The other is an electrical-driven actuator integrated with an energy storage function. Especially, the functions of actuation and energy storage can be simultaneously/independently used without interfering with each other. We provide comprehensive research from the material level (CNT-polymer composites) to the device level (actuators, supercapacitors, EMI shielding devices), and then to the system level (multi-functional actuators). We believe that the integration design of the multi-functional actuators will open up new avenues for the development of soft robotics, wireless signal transmission switch, and deformable supercapacitors.