Nanotube Nanocomposite Films Research Articles

Continuously fabricated transparent conductive polycarbonate/carbon nanotube nanocomposite films for switchable thermochromic applications

Flexible CNT-based transparent conductive films with strong adhesion were continuously fabricated by a home-made roll-to-roll (R2R) spraying method and used as a smart window with switchable transparency.

85 MeV C6+ swift heavy ion irradiation of in-situ reduced graphene oxide–polypyrrole nanotubes nanocomposite films for supercapacitor electrodes

Hybrid nanocomposites of reduced graphene oxide (RGO) and polypyrrole nanotubes (PPyNTs) have been synthesized by in-situ reduction of graphene oxide. The nanocomposite films are modified by swift heavy ion irradiation with 85 MeV C6+ ions at different fluences of 6 × 1010, 3.6 × 1011, 2.2 × 1012 and 1.3 × 1013 ions cm−2. Morphological, structural, thermal and electrical properties of the irradiated nanocomposites have been investigated by FESEM, HRTEM, XRD, thermogravimetric analyzer and conductivity measurements. The BET specific surface area and porosity of the nanocomposites have been determined by N2 adsorption-desorption measurements. The fluence dependent electrochemical performance of the irradiated nanocomposites as electrodes has been studied by cyclic voltammetry, galvanostatic charge-discharge and impedance spectroscopy. The electrochemical studies reveal that the capacitive properties improved upto a fluence of 2.2 × 1012 ions cm−2 and decreases at higher fluence. A highest specific capacitance of 346 F g−1 and cyclic stability of 89% is achieved for the irradiated nanocomposite compared to 299 F g−1 and 77% of that of pristine. The increase of capacitive performance may be ascribed to the increase in surface area and pore size of the pristine electrode with increasing irradiation fluence, which extends the ion transport from the surface to the bulk of the electrode. Decrease in the diameter of PPyNTs is observed from FESEM images with increase in ion fluence, which may also contribute to higher charge storage by increasing the overall surface area of the electrode.

Preparation and characterisation of poly(vinyl) alcohol (PVA)/starch (ST)/halloysite nanotube (HNT) nanocomposite films as renewable materials

1) The symbol “wf” in Eq. (2) on p. 3458 denotes the weight fraction of HNTs in PVA/ST/HNT nanocomposites.

Design of a nanocomposite substrate inducing adult stem cell assembly and progression toward an Epiblast-like or Primitive Endoderm-like phenotype via mechanotransduction.

This work shows that the active interaction between human umbilical cord matrix stem cells and Poly (l-lactide)acid (PLLA) and PLLA/Multi Walled Carbon Nanotubes (MWCNTs) nanocomposite films results in the stem cell assembly as a spheroid conformation and affects the stem cell fate transition. We demonstrated that spheroids directly respond to a tunable surface and the bulk properties (electric, dielectric and thermal) of plain and nanocomposite PLLA films by triggering a mechanotransduction axis. This stepwise process starts from tethering of the cells' focal adhesion proteins to the surface, together with the adherens junctions between cells. Both complexes transmit traction forces to F-Actin stress fibres that link Filamin-A and Myosin-IIA proteins, generating a biological scaffold, with increased stiffening conformation from PLLA to PLLA/MWCNTs, and enable the nucleoskeleton proteins to boost chromatin reprogramming processes. Herein, the opposite expression of NANOG and GATA6 transcription factors, together with other lineage specification related proteins, steer spheroids toward an Epiblast-like or Primitive Endoderm-like lineage commitment, depending on the absence or presence of 1wt% MWCNTs, respectively. This work represents a pioneering effort to create a stem cell/material interface that can model the stem cell fate transition under growth culture conditions.

R-GO/MWCNTs Nanocomposite Film as Electrode Material for Supercapacitor

We synthesized a reduced graphene oxide (r-GO) multi-walled carbon nanotube (MWCNTs) nanocomposite film via layer by layer (LBL) assembly. This structure was prepared by vacuum filtration and heat-treated at a low temperature of 500°C. The morphology of the sample was determined by field emission electron spectroscopy (FE-SEM). The structural detail and the chemical analysis were characterized by using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The cyclic voltammetry (CV) curve of r-GO/MWCNTs nanocomposite appeared nearly rectangular in shape. The current density (A/g) was gradually increased by increasing the scan rate of the voltage, as high as a scan rate of 500 mVs-1. At a current density of 10 mAg-1, the specific capacitance of the nanocomposite, estimated by galvanostatic (GA) charge/discharge measurement, is 150 Fg-1. These nanocomposites can be developed for supercapacitor electrodes.

Understanding physicochemical properties changes from multi-scale structures of starch/CNT nanocomposite films

From the view of multi-scale structures of hydroxypropyl starch (HPS)/carbon nanotube (CNT) nanocomposite films, the film physicochemical properties were affected by comprehensive factors including molecular interaction, short range molecular conformation, crystalline structure and aggregated structure. The less original HPS hydrogen bonding that was broken, less decreased order of HPS short range molecular conformation, lower film crystallinity and larger size of micro-ordered regions contributed to higher tensile strength and Young’s modulus of the film with CNT content of 0.5% (g/g, CNT in HPS). The higher film overall crystallinity and larger size of micro-ordered regions of the film with CNT content of 0.05%–0.3% compared with those of control contributed to better film barrier property. The addition of CNT with the content of 0.05%–0.5% broke the original HPS hydrogen bonding and decreased the order of starch short range molecular conformation, which counteracted the positive effect of CNT on the thermal stability of the material, thus thermal degradation temperature of these nanocomposite films did not increase. But the sharp increase of film crystallinity increased film thermal degradation temperature. This study provided a better understanding of film physicochemical properties changes which guides to rational design of starch-based nanocomposite films for packaging and coating application.

Co-electrodeposition and characterisation of platinum nanoparticle-multi-walled carbon nanotube nanocomposite films as good electrocatalysts

Platinum nanoparticle-multi-walled carbon nanotube (Pt-MWCNT) nanocomposite films supported on titanium substrate were prepared by the co-electrodeposition method. This nanocomposite catalyst was characterised by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy and electrochemical methods. The SEM images reveal that nanostructures are distributed at the surface of the titanium plate. Electro-oxidation of methanol was investigated in acidic media on Pt-MWCNTs/Ti electrodes via cyclic voltammetric analysis in the mixed 0.1 M methanol and 0.1 M H2SO4 solutions. The Pt-MWCNTs/Ti catalyst has good electro-catalytic activity for methanol oxidation. This novel Pt-MWCNTs/Ti catalyst can be used repeatedly and exhibits stable electro-catalytic activity for the methanol oxidation.

Thermal and electrical properties of poly(phenylene sulfide)/carbon nanotube nanocomposite films with a segregated structure

Structurally segregated poly(phenylene sulfide) (PPS)-based nanocomposite films containing multiwalled carbon nanotube (MWCNT) of 0.5–10.0wt% were manufactured by solid-mixing and following melt-compression. The cross-sectional optical and electron microscopic images of the nanocomposite films revealed that MWCNTs form a segregated and percolated conductive network structure in the PPS matrix. DSC and TGA data demonstrated that melt-crystallization temperatures and thermal degradation temperatures of the nanocomposite films are slightly increased with the MWCNT content, which are owing to the nucleating agent and thermal protection effects of MWCNTs, respectively. The electrical conductivity of the nanocomposite films increased significantly from ∼10−10 to ∼0.11S/cm with the increment of the MWCNT content from 0.0 to 10.0wt%, especially at a low percolation threshold of ∼0.33wt%MWCNT. Accordingly, PPS-based nanocomposite films with 1.0–10.0wt% MWCNT exhibited high performance in electrical resistive heating behavior under applied voltages of 5–100V by achieving steady-state maximum temperatures of 30–190°C within a relatively short period of time of ∼10s.

Transparent poly(lactic acid)/halloysite nanotube nanocomposites with improved oxygen barrier and antioxidant properties

Poly(lactic acid) (PLA)/halloysite nanotube (HNT) nanocomposite thin films were prepared via melt compounding followed by compression molding. Epoxidized natural rubber (ENR) was used to toughen the PLA/HNT nanocomposites. The effects of the HNTs and ENR on the oxygen permeability of the PLA films were evaluated. The oxidation onset temperatures (OOTs) of the PLA nanocomposites were measured using differential scanning calorimetry (DSC), and the thermal decomposition was assessed by thermogravimetric analysis (TG). PLA/HNT6/ENR5 exhibits the lowest oxygen permeability coefficient of the films studied, which indicates that the barrier properties of PLA/HNT6 were enhanced by the incorporation of 5 mass% ENR. From the DSC results, the addition of 6 mass% HNT shifted the OOT of the PLA to higher temperatures, improving the antioxidant properties of the PLA nanocomposites. The thermal decomposition behavior of the PLA/HNT nanocomposites depends on the HNT loading, ENR loading, and testing environment (i.e., nitrogen and oxygen). The TEM images suggest that ENR promoted good interaction between the PLA and HNT, which confirms that good adhesion between HNT and ENR generates longer tortuous pathways for oxygen permeation and results in a PLA/HNT nanocomposite with enhanced barrier properties.

Structure–property relationship of halloysite nanotubes/ethylene–vinyl acetate–carbon monoxide terpolymer nanocomposites

Poly(ethylene- co-vinyl acetate- co-carbon monoxide) (EVACO)/halloysite nanotube (HNT) nanocomposite films were solution cast. Dispersion of HNTs in the matrix was analyzed by elemental mapping and the role of HNTs on crystallizability, flammability and thermal, mechanical, and electrical properties of the polymer was evaluated. The nature of interaction between the EVACO matrix and HNTs was studied using Fourier transform infrared spectroscopy. The highest tensile strength was observed for the composite with 1% filler loading, whereas the highest crystallinity was observed for that with 3% filler loading. The decay in the tensile properties at higher filler loading was due to agglomeration of HNTs and debonding of polymer–filler interface. The electrical volume resistivity of the composites decreased with HNT loading because of the ionic charge transfer. The direct current electrical resistivity study of the composites proves that the addition of HNT can improve the antistatic properties of the polymer.

Flexible and free-standing ternary Cd2GeO4 nanowire/graphene oxide/CNT nanocomposite film with improved lithium-ion battery performance

To realize flexible lithium-ion batteries (LIBs), the design of flexible electrode/current collector materials with high mechanical flexibility, superior conductivity and excellent electrochemical performance and electrical stability are highly desirable. In this work, we developed a new ternary Cd2GeO4 nanowire/graphene oxide/carbon nanotube nanocomposite (Cd2GeO4 NW/GO/CNT) film electrode. Benefiting from the efficient combination of GO and Cd2GeO4 NWs, our Cd2GeO4 NW/GO/CNT composite film exhibits a capacity of 784 mA h g−1 after 30 cycles at 200 mA g−1, which is 2.7 times higher than that of Cd2GeO4 NW/CNT film (290 mA h g−1). At a higher rate of 400 mA g−1 and 1 A g−1, the Cd2GeO4 NW/GO/CNT film delivers a stable capacity of 617 and 397 mA h g−1, respectively. Even at 2.5 A g−1, it still exhibits a high rate capacity of 180 mA h g−1. The flexible Cd2GeO4 NW/GO/CNT film clearly demonstrates good cycling stability and rate performance for anode materials in LIBs. This route may be extended to design other flexible free-standing metal germanate nanocomposite anode materials.

Eco-friendly synthesis and catalytic application of chitosan/gold/carbon nanotube nanocomposite films

Novel eco-friendly chitosan nanocomposite membranes containing gold nanoparticles and carbon nanotubes (CNTs) have been synthesized to produce reusable catalytic membranes.

Enhanced Formaldehyde-Sensing Performances of Mixed Polyethyleneimine-Multiwalled Carbon Nanotubes Composite Films on Quartz Crystal Microbalance

The development of a robust, reproducible, cheap, and low-power gas sensor for monitoring the low-level concentration of formaldehyde is in urgent demand. In this paper, mixed polyethyleneimine (PEI)–multiwalled carbon nanotubes (MWCNTs) nanocomposite thin film was coated on a quartz crystal microbalance (QCM) using a facile spraying process for formaldehyde detection at room temperature. The effects of spraying loads and ratios of PEI to MWCNTs on sensing properties were investigated. The hydrogen-bonding interaction between PEI and MWCNTs was proved by the X-ray photoelectron spectrometer (XPS) characterization, and the formaldehyde-sensing characteristics results revealed that the PEI-MWCNTs nanocomposite film sensor exhibited superior sensing properties than the pure PEI film sensor, with linear response characteristics, fast response, low detection limit (0.6ppm), good reproducibility and selectivity to formaldehyde within 6 ppm. A sensing mechanism model was introduced to understand the chemical reaction between formaldehyde gas molecules and amine functional groups of PEI along with the ultraviolet-visible absorption spectra analysis. This paper shows the great potential for developing sensitive and fast-response formaldehyde gas sensor with a simple spraying fabrication method.

Conductive-on-demand: Tailorable polyimide/carbon nanotube nanocomposite thin film by dual-material aerosol jet printing

A new nanocomposite manufacturing process, Dual-material aerosol jet printing (DMAJP), was developed to fabricate polyimide (PI)/carbon nanotube (CNT) nanocomposite with tailorable and controllable intra-part varying CNT loading. This process mixes the aerosols of CNT ink and a solution of PI precursor to achieve a homogenous dispersion of CNTs in the PI matrix. The mixing ratio of the two aerosols determines the CNT loading in the nanocomposite, which can be used to control the conductivity of the film. Thickness, nanostructure, and conductivity of the nanocomposites fabricated under different process conditions were investigated. The high degree with which the printed PI/CNT nanocomposite film may be tailored was demonstrated through three examples: a film with different CNT loadings at designated regions; a film with a built-in circuit; and a film with a through-thickness conductive channel. DMAJP is a facile, versatile, and potentially scalable manufacturing process for the next generation of smart nanocomposites.

Immobilization of hemoglobin on functionalized multi-walled carbon nanotubes-poly-l-histidine-zinc oxide nanocomposites toward the detection of bromate and H2O2

A novel biocompatible sensing strategy has been developed based on functionalized multi-walled carbon nanotube (f-MWCNT), poly-l-histine (P-l-His), and ZnO nanocomposite film for the immobilization of hemoglobin (Hb). The direct electron transfer properties and bioelectrocatalytic activity of the Hb in f-MWCNT–P-l-His–ZnO composite film is further investigated. The apparent heterogeneous electron transfer rate constant (ks) of Hb confined to f-MWCNT–P-l-His–ZnO nanocomposite is found to be 5.16s−1 using Laviron's equation. Moreover, the surface coverage concentration (Γ) of the electroactive Hb in the f-MWCNT–P-l-His–ZnO film is estimated to be 1.88×10−9molcm−2. The fabricated electrochemical biosensor based on the immobilized Hb revealed a fast response time (<3s) with a wide linear range (4–18,000μM and 2–15,000μM) and detection limit (as low as 0.01μM and 0.30μM) for the electrocatalytic determination of a mediator-free H2O2 and bromate under optimal experimental conditions. The ca. apparent Michaelis–Menten constant is 0.14mM, which indicates that the Hb has a high affinity to H2O2. The high sensitivity, good reproducibility, and long-term stability of the proposed nanocomposite film indicates that it can serve as an electrode for the development of an amperometric H2O2 and bromate-based biosensor. The proposed third-generation biosensor was successfully applied to milk and urine samples for the detection of H2O2 and bromate.

Mechanical and biological properties of silk fibroin/carbon nanotube nanocomposite films

Multi-walled carbon nanotubes (MWCNTs) were homogeneously dispersed in silk fibroin (SF) solutions at different compositions, and a simple solvent-casting method was used to fabricate SF/MWCNT films. Structure, viscosity, and mechanical properties of the SF/MWCNT nanocomposites were characterized by FTIR (Fourier Transform Infrared Spectroscopy), viscometry, and tensile testing. Fibroblast cells were used to examine cell viability and attachment to nanocomposite films. Compared to a pure SF film, adding just 0.5 % (w/w) of MWCNT to the SF matrix could enhance the Young’s modulus and ultimate tensile strength by approximately 24 % and 39 %, respectively. In addition, with increasing MWCNTs content, the percentage of β-sheet structure increased significantly. When the content of MWCNTs increased from 0 to 1 % (w/w), the β-sheet content improved from 17.8 % to 53.6 %. Furthermore, adding up to 1 % (w/w) MWCNT increased the viscosity of the SF solution ten fold. From a biological point of view, no toxic effect was observed on fibroblast cells in the presence of MWCNTs after 3 and 7 days. This investigation suggests that SF/MWCNT nanocomposite films with improved mechanical properties and biocompatibility are well-suited as novel biomaterials.

Highly efficient Ceramic-SWCNT based free standing films for gas sensing application

This paper presents a method of preparation of ceramic-carbon nanotube nanocomposite films using a gel-cast technique to improve the sensitivity of the carbon nanotubes based gas sensor for toxic gases (NH3, NO2) to a sub-ppm levels. A detailed study is presented on nanocompostite synthesis, sensing mechanism and performance of free standing nanocomposites film. The method is simple, low cost, environment friendly and allows batch fabrication process. The film was prepared by a motor driven machine fitted with doctor׳s blade where single wall carbon nanotube(SWCNT) powder dispersed in sol–gel based alumina solution was poured and rolled out on Mylar tape at specific speed to have control on film thickness. Electron microscopy, Energy-dispersive X-ray and Raman Spectroscopy were used to characterize the morphology and composition of prepared material. The proposed free standing nanocomposite film shows excellent and stable sensitivity to NH3 and NO2 molecules are 15% and 32% for 1ppm respectively

Electrochemical Impedance Spectroscopy Study on Corrosion Protection of Acrylate Nanocomposite on Mild Steel Doped Carbon Nanotubes

Acrylate:carbon nanotubes (A:CNTs) nanocomposite thin film was prepared by sol- gel technique. The corrosion coating protection of acrylate:carbon nanotubes (CNTs) nanocomposite thin film has been coated on mild steel characterised by electrochemical impedance spectrometer (EIS) measurement and equivalent circuit model are employed to analyse coating impedance for corrosion protection. In this study, 3.5 w/v % sodium chloride (NaCl) solution was immersed the acrylate:carbon nanotubes nanocomposite thin film. As the results, the surface morphology were found that there formation of carbon nanotubes with good distribution on acrylate-based coating. From EIS measurement, A:CNTs nanocomposite thin film with 0.4 w/v % contain of CNTs was exhibited the highest coating impedance from Nyquist graph after immersed in sodium chloride solution and may provide the excellent corrosion protection. The Bode plots have shown the impedance is high at the beginning from the time at high frequency and slightly decreases with value of frequency become smaller.

Fabrication and Formaldehyde-Sensing Property of Quartz Crystal Microbalance (QCM) Coated with PVP-MWCNTs Composites

In this paper, the quartz crystal microbalance (QCM) sensors coated with polyvinyl pyrrolidone (PVP)-multiwalled carbon nanotubes (MCWNTs) nanocomposite thin films were developed by the spray process, which were used for the detection of low concentration formaldehyde at room temperature. The surface morphology and structure of films was analyzed by scanning electron microscope (SEM), UV-Vis absorption spectrometry, respectively, and the formaldehyde-sensing properties of sensors were investigated. The results showed that the prepared QCM gas sensor exhibited the linear characteristic, fast response, good reproducibility to low concentration formaldehyde within 6 ppm, and the poisoning of films was observed when the formaldehyde concentration exceeded 6ppm. Moreover, the sensitivity of the sensor could achieve up to 1Hz/ppm and had the good stability of response values.

Preparation of Polyimide/MWCNT Nanocomposites via Solid State Shearing Pulverization (S3P) Processing.

Polyimide/multiwall carbon nanotube (PI/MWCNT) nanocomposite films with homogeneous MWCNTs dispersion were prepared via a solid state shearing pulverization (S3P) approach. Polyimide precursor, viz., poly(amic acid) (PAA), was synthesized from 4,4'-oxydianiline (ODA) and pyromellitic dianhydride (PMDA). Then, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) was mixed with the PAA powder and acid functionalized MWCNTs (acid-MWCNTs) by solid state shearing pulverization (S3P) approach. Finally, PI/MWCNT nanocomposite films were prepared by thermal imidization at elevated temperatures. Using such an approach not only the MWCNTs are well-dispersed but also the mechanical and thermal properties of PI are improved. The tensile strength of PI was enhanced by 74% and the elongation at break decreased to 10.35% with 5.0 wt% acid- MWCNT loading. And the glass transition temperature of PI was increased to 341 degrees C from 303 degrees C because of the strong interfacial bonding between PI and acid-MWCNTs. The solid state shearing pulverization (S3P) approach developed in this study provides a novel method to prepare various polymer composites with desired particle dispersion.