Presence Of Multi-walled Carbon Nanotubes Research Articles

Melt-mixed nanocomposites of SIS/MWCNT: rheological, electrical and structural behavior

Abstract In this work, nanocomposites based on the triblock copolymer polystyrene-b-polyisoprene-b-polystyrene (SIS) thermoplastic elastomer filled with multiwall carbon nanotubes (MWCNT) were obtained by melt mixing. The nanocomposites were characterized by oscillatory rheometry, electrical resistivity, small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM). The results showed that both, rheological and electrical percolation were achieved at MWCNT loadings between 1-3 vol.%. Rheological tests revealed that the insertion of MWCNT into SIS significantly enhanced the process of relaxation of SIS blocks. Resistivity measurements revealed that conductive nanocomposites were obtained at MWCNT loadings ~1.6 vol.%. The electrical resistivity decreased eleven orders of magnitude from neat SIS to SIS/ 5 vol.% MWCNT. Finally, SAXS and TEM showed that the melt mixing process and the presence of MWCNT hampered the self-assembly of SIS into well-ordered domains.

Effect of Functionalized Multiwalled CNTs on the Selective Formation of Calcium Oxalate Crystals by Electrocrystallization

The electrocrystallization (EC) of calcium oxalate (CaOx) crystals in the presence of multiwalled carbon nanotubes (MWCNTs) functionalized with itaconic acid (IA) and the monoester derivatives mono...

Preparation and characterisation of polypyrrole – carbon nanomaterial composite solid-phase microextraction fibres and their applications to the determination of fungicide residues in grape juice samples

ABSTRACT Present study describes the use of a lab-made polypyrrole (PPy) coated solid phase microextraction (SPME) fibres modified with carbonaceous nanomaterials for effective adsorption of volatile fungicides used in vineyards for subsequent determination by gas chromatography coupled with a mass spectrometer. The SPME fibres were fabricated electrochemically by dipping a stainless steel wire in a cell containing pyrrole monomer where the polymeric film was coated on the wire by cycling the potential between −0.5 and 2.0 V at a rate of 50 mV s−1. Then, the procedure was repeated in the presence of multi-walled carbon nanotubes (MWCNTs) or graphene (Gr) nanoplates dispersed in tartrate solution. The coated fibres were attached to a holder for subsequent headspace extraction of volatile fungicides in grape juice samples. Initial studies were conducted with commercial fibres adoptable to a fully automated system and optimal conditions were studied by using an 85 µm PA fibre. Then, the fabricated fibres have been tested manually under optimised conditions for unbiased comparison. Overall results have suggested that PPy-MWCNT-SPME and PPy-Gr-SPME have given the comparable results with commercial fibres in the concentration range of 1.0–50 ng mL−1 by allowing the determination of these fungicides at LOQ levels varied in the range of 0.55–6.94 ng mL−1 ranges. In comparison to the literature values, more results that are sensitive were obtained with these two fibres with satisfactory recovery values without any solvent consumption or labour-intensive pre-treatment processes.

Electropolymerized MIP with MWCNTs on Stir Bar Using Multivariate Optimization for Tetradifon Detection in Date

Multi-walled carbon nanotubes (MWCNT) adjunct to molecularly imprinted polymers (MIP) have advantages of the large surface area of nanoparticles and selectivity of MIPs for selective extraction of tetradifon as a widely used pesticide in date palm. The main aims were the use of experimental design, electrochemical synthesis and ultra-high performance liquid chromatography (UHPLC) to develop a simple, reliable and precise pesticide residue analysis method as an important aspect of food and drug quality control for the determination of tetradifon in date palms. An MIP in the presence of MWCNT was synthesized by cyclic voltammetric technique on a steel rod to produce a composite of MIP-MWCNTs for stir bar extraction of tetradifon residue in date samples. The experimental design was used to optimize MIPMWCNT composite synthesis through the screening of eight variables. The composite was characterized by scanning electron microscopy (SEM). Tetradifon was determined in extracted samples by UHPLC under optimum conditions. A very thin film was made by MIP-MWCNT coated on a steel rod which was repeatable and had good adhesion and persistence. The detection limit (LOD) and the quantification limit (LOQ) of the method were measured as 16 and 49 ng/ml, respectively. Average recovery of tetradifon at the two spiked levels was observed to be as low as 86.5% to 90.7% (RSD from 0.79% to 1.04%). The low cost, high selectivity, good reproducibility, acceptable intra and inter day precision and accuracy developed method were successfully applied to determine tetradifon residue in date samples purchased from a local market.

Properties of Cracking Patterns of Multi-Walled Carbon Nanotube-Reinforced Cement Matrix.

The research presented in this paper presents a quantitative analysis of cracking patterns on the surface of cement paste, which has been modified by the addition of the multi-wall carbon nanotubes (MWCNTs). The cracking patterns analyzed were created as a result of increased temperature load. MWCNTs were used as an aqueous dispersion in the presence of a surfactant, sodium dodecyl sulfate (SDS). Four series of the cement paste were tested, and the samples differed in the water/cement (w/c) ratio, cement class, and the presence of MWCNTs. Image analysis tools were used to quantify the cracking patterns and it was proposed to measure parameters, such as the average cluster area, average cluster perimeter, average crack width, and crack density. In order to facilitate the image analysis process, the sample surface was subjected to preparation and using statistical analysis tools it was assessed whether the method of surface preparation affects the way the sample is cracked. The paper also presents the analysis of the relationships that occur between parameters describing the cracking patterns, and also with the physico-mechanical properties of the cement pastes. It was attempted to explain the dependencies using elements of fractal theory and the theory of dispersion systems.

Improved Solid-Contact Nitrate Ion Selective Electrodes Based on Multi-Walled Carbon Nanotubes (MWCNTs) as an Ion-to-Electron Transducer.

Possible improvement of the performance characteristics, reliability and selectivity of solid-contact nitrate ion-selective electrodes (ISE) (SC/NO3−-ISE) is attained by the application of a nitron-nitrate (Nit+/NO3−) ion association complex and inserting multi-walled carbon nanotubes (MWCNTs) as an ion-to-electron transducer between the ion sensing membrane (ISM) and the electronic conductor glassy carbon (GC) substrate. The potentiometric performance of the proposed electrode revealed a Nernstian slope −55.1 ± 2.1 (r² = 0.997) mV/decade in the range from 8.0 × 10−8–1 × 10−2 M with a detection limit of 2.8 × 10−8 (1.7 ng/mL). Selectivity, repeatability and reproducibility of the proposed sensors were considerably improved as compared to the coated disc electrode (GC/NO3−-ISE) without insertion of a MWCNT layer. Short-term potential stability and capacitance of the proposed sensors were tested using a current-reversal chronopotentiometric technique. The potential drift in presence of a MWCNT layer decreased from 167 μVs−1 (i.e., in absence of MWCNTs) to 16.6 μVs−1. In addition, the capacitance was enhanced from 5.99 μF (in absence of MWCNTs) to 60.3 μF (in the presence of MWCNTs). The presented electrodes were successfully applied for nitrate determination in real samples with good accuracy.

An integrated approach to determine interactive genotoxic and global gene expression effects of multiwalled carbon nanotubes (MWCNTs) and benzo[a]pyrene (BaP) on marine mussels: evidence of reverse ‘Trojan Horse’ effects

The interactions between carbon-based engineered nanoparticles (ENPs) and organic pollutants might enhance the uptake of contaminants into biota. The present integrated study aimed to assess this potential ‘Trojan Horse’, probing the interactive effects of purpose-made multi-walled carbon nanotubes (MWCNTs), a representative ENP, and benzo[a]pyrene (BaP), a ubiquitous polycyclic aromatic hydrocarbon (PAH) pollutant, on the marine mussel Mytilus galloprovincialis. Mussels were exposed to MWCNTs and BaP either alone or in various combinations. The co-exposure of BaP with MWCNTs revealed that the presence of MWCNTs enhanced the aqueous concentrations of BaP, thereby reducing the uptake of this pollutant by mussels as evidenced by lowering BaP concentrations in the tissues. Determination of DNA damage (comet assay) showed a concentration-dependent response for BaP alone which was absent when MWCNTs were present. Global gene expression using microarray analyses indicated that BaP and MWCNTs, in combination, differentially activated those genes which are involved in DNA metabolism compared to the exposures of BaP or MWCNTs alone, and the gene expression response was tissue-specific. Mechanisms to explain these results are discussed and relate primarily to the adsorption of BaP on MWCNTs, mediated potentially by van der Waals interactions. The use of a novel approach based on gold-labeled MWCNTs to track their uptake in tissues improved the traceability of nanotubes in biological samples. Overall, our results did not indicate the ‘Trojan Horse’ effects following co-exposure to the contaminants and clearly showed that the adsorption of BaP to MWCNTs modified the uptake of the pollutant in marine mussels.

Surface modification of aluminum alloys with carbon nanotubes by laser surface melting

Carbon nanotubes (CNTs) could be an excellent reinforcement for metal matrix composites, specifically for composites with aluminum or aluminum alloy matrix. Surface modification to improve hardness and other material properties has been performed by laser surface melting (LSM) process, where the laser beam melts the substrate together with alloying elements or reinforcing phase additives. In this work, Multiwalled CNTs (MWCNTs) were mixed by the electrostatic adsorption process with aluminum powder and the resulting mixed powder was laser melted on the surface of a 6061-aluminum alloy substrate. As a result, a modified substrate surface has been obtained from the Al/MWCNT – substrate co-melting, dilution and re-solidification processes. This modified layer was obtained by different LSM parameters and were characterized by Optical (OM) and Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Field Emission Gun Scanning Electron Microscopy (FEG-SEM), X-Ray Diffraction (XRD) and Raman Spectroscopy (RS). The resulting mechanical behavior was evaluated by Vickers microhardness tests. The results showed that the presence of MWCNT in the aluminum powder improves the laser energy absorption, leading to the formation of a deeper modified layer, with segregation of Si particles homogeneously dispersed and improving the hardness. The formation of Al4C3 was not observed, evidencing that the MWCNTs did not react with the molten Al matrix during the LSM process.

Surface modification of β-type titanium with multi-walled CNTs/ μ-HAp powder mixed Electro Discharge Treatment process

The present study addresses the surface modification of β-type titanium substrate by the Electro Discharge Treatment (EDT). This technique incorporates multi-walled carbon nanotubes (MWCNTs), and μ-hydroxyapatite (μHAp) powders in the dielectric medium to achieve bio-favorable substrate. The L18 array is employed to conduct the experiments considering tool polarity, peak current, pulse duration, dielectric medium, and electrode tool material as a process parameters. The treated surface is scrutinized in terms of cell viability and hemolysis which concludes that the presence of MWCNTs on the surface promotes cell proliferation. Surface morphology also confirmed that powder mixed electro-discharge treatment elevates the porosity that is advantageous for bone grafting. X-Ray pattern revealed the formation of biocompatible phases of oxides, carbide, and hydride for the surface treated in the presence of MWCNTs mixed dielectric medium. The positive polarity of the graphite tool electrode at 15 A is the most desirable process parameter developing the bioactive surface.

Impact of different isothermal aging conditions on the IMC layer growth and shear strength of MWCNT-reinforced Sn–5Sb solder composites on Cu substrate

In this study, the effect of multi-walled carbon nanotubes (MWCNTs) reinforcement on the intermetallic compound (IMC) layer growth and shear strength of Sn–5Sb-xCNT/Cu composite solder joints subjected to different isothermal aging conditions has been investigated. A series of plain and composite lead-free solder systems (Sn–5Sb-xCNT; x = 0, 0.01, 0.05 and 0.1 wt%) was successfully developed through the powder metallurgy method. Isothermal aging process was performed on the solder/Cu joints at 120 °C, 150 °C and 170 °C temperatures in order to investigate the evolution of the interfacial IMC layers and the shear strength property. Experimental results showed that the thickness of the total IMC layer increased with rising aging temperature. While the Cu3Sn IMC maintained a layer-type morphology for all aging conditions, morphology of the Cu6Sn5 IMC transformed from a scallop-type to a layer-type after aging at intermediate (150 °C) and high (170 °C) temperatures. Given the potential of MWCNTs as a reinforcement material, significant suppression in IMC layer growth was demonstrated by the composite solder joints relative to the plain counterpart. Comprehensive investigation on the growth kinetics showed that the presence of MWCNTs in the composite solder joints was effective in slowing down the diffusion mechanism responsible for IMC growth. Overall, the Sn–5Sb-0.05CNT composite solder joint exhibited the lowest diffusion coefficient within the range of 0.09 × 10−14- 1.03 × 10−14 cm2/s and 0.95 × 10−14- 9.8 × 10−14 cm2/s for Cu6Sn5 and Cu3Sn IMC layers respectively. Moreover, the strengthening effect of the MWCNTs reinforcement was well marked in the composite solder joints as the maximum shear strength within a range of 24.2–15.2 MPa was exhibited by the Sn-0.01CNT/Cu composite solder joint subjected to reflow soldering and isothermal aging conditions.

Physical, mechanical and biological evaluation of poly (3-hydroxybutyrate)-chitosan/MWNTs as a novel electrospun scaffold for cartilage tissue engineering applications

ABSTRACTDesigning scaffolds with appropriate mechanical properties is a challenge in tissue engineering. In this study, electrospun scaffolds were fabricated by mixing different percent of multi-walled carbon nanotubes (MWNTs) with poly (3-hydroxybutyrate) (PHB)-chitosan solution. Scanning electron microscopy of the scaffolds revealed bead-free nanofibers with pore volume of 83%, which had a direct relationship with fiber diameter. The nanocomposite scaffolds exhibited higher hydrophilicity and lower degradation rate due to the presence of MWNTs. The tensile strength of scaffolds improved significantly in the presence of MWNTs (about three-fold higher than PHB-chitosan). Chondrocyte culture study showed better cell adhesion and growth in nanocomposite scaffolds.

Thinning of glycerol in the presence of multi-walled carbon nanotubes

Hydrogen bonding is an important index to determine the viscosity of liquids containing a hydroxyl group. The change of hydrogen bond must change the viscosity of liquid. Glycerol is a kind of polyhydroxy high viscosity liquid. The rheological property is one of the biggest concerns for glycerol. Reduction of glycerol viscosity without diluting or heating to change its hydrogen bonding is considered to be challenging. Here, we demonstrate the effect of multiwalled carbon nanotubes (MWNTs) on the thinning of glycerol. The viscosity of glycerol was decreased at certain proportions, with a viscosity reduction range of 0.54%–1.17%. The hydrogen bond network was broken by the adsorption and space-limiting effect of MWNTs. Transmission electron microscopy and computer simulation results showed that glycerol molecular clusters were mainly dispersed on the surface of MWNTs and adsorbed into the internal pipe of MWNTs. A cavity between the glycerol molecules and MWNTs performed the space-limiting role of MWNTs. MWNTs simultaneously acted as a viscosifier and viscosity reducer. These two effects show a competitive relationship with the amount of additional changes. We expect these results to provide a new perspective in controlling rheological behavior and reveal the underlying interaction between hydroxy liquids and nanomaterials.

Peroxisome Proliferator–activated Receptor-γ Deficiency Exacerbates Fibrotic Response to Mycobacteria Peptide in Murine Sarcoidosis Model

We established a murine model of multiwall carbon nanotube (MWCNT)-elicited chronic granulomatous disease that bears similarities to human sarcoidosis pathology, including alveolar macrophage deficiency of peroxisome proliferator-activated receptor γ (PPARγ). Because lymphocyte reactivity to mycobacterial antigens has been reported in sarcoidosis, we hypothesized that addition of mycobacterial ESAT-6 (early secreted antigenic target protein 6) to MWCNT might exacerbate pulmonary granulomatous pathology. MWCNTs with or without ESAT-6 peptide 14 were instilled by the oropharyngeal route into macrophage-specific PPARγ-knockout (KO) or wild-type mice. Control animals received PBS or ESAT-6. Lung tissues, BAL cells, and BAL fluid were evaluated 60 days after instillation. PPARγ-KO mice receiving MWCNT + ESAT-6 had increased granulomas and significantly elevated fibrosis (trichrome staining) compared with wild-type mice or PPARγ-KO mice that received only MWCNT. Immunostaining of lung tissues revealed elevated fibronectin and Siglec F expression on CD11c+ infiltrating alveolar macrophages in the presence of MWCNT + ESAT-6 compared with MWCNT alone. Analyses of BAL fluid proteins indicated increased levels of transforming growth factor (TGF)-β and the TGF-β pathway mediator IL-13 in PPARγ-KO mice that received MWCNT + ESAT-6 compared with wild-type or PPARγ-KO mice that received MWCNT. Similarly, mRNA levels of matrix metalloproteinase 9, another requisite factor for TGF-β production, was elevated in PPARγ-KO mice by MWCNT + ESAT-6. Analysis of ESAT-6 in lung tissues by mass spectrometry revealed ESAT-6 retention in lung tissues of PPARγ-KO but not wild-type mice. These data indicate that PPARγ deficiency promotes pulmonary ESAT-6 retention, exacerbates macrophage responses to MWCNT + ESAT-6, and intensifies pulmonary fibrosis. The present findings suggest that the model may facilitate understanding of the effects of environmental factors on sarcoidosis-associated pulmonary fibrosis.

Recycled carbon fibre/Bi2Te3 and Bi2S3 hybrid composite doped with MWCNTs for thermoelectric applications

In this study, a cost-effective thermoelectric generator was developed from recycled carbon fibre (RCF) composites incorporated with multi-walled carbon nanotubes (MWCNT) doped bismuth telluride (Bi2Te3) and bismuth sulphide (Bi2S3). A facile approach utilising hot compression and brushing was used to prepare a cost-effective inorganic RCF thermoelectric composite with varying content of MWCNT ranging from 0.05 to 0.20 wt%. This work investigated the effect of doping MWCNT in Bi2Te3 and Bi2S3 matrix and its corresponding effect on thermoelectric, morphological, structural and thermal properties of RCF thermoelectric composite. The thermoelectric properties of RCF composites were optimised at 0.10 wt % (1.044 μW K−2m−1) and 0.15 wt% (0.849 μW K−2m−1) of MWCNT for doped Bi2Te3 and Bi2S3 respectively. The addition of MWCNT reduced the difference in power factor between RCF-Bi2Te3 and RCF-Bi2S3 from 52% to 19%. The presence of MWCNT in the Bi2S3 matrix overcame the high resistivity of Bi2S3 and improved its thermoelectric properties as MWCNT provided a conductive pathway for efficient electron transfer. Thus, MWCNT doped Bi2S3 RCF composites is an alternative to telluride free thermoelectric generators.

Characterization of electrospun poly(lactide) composites containing multiwalled carbon nanotubes

The main aim of this work was to obtain conductive polymer-based materials by incorporation of different amounts of multiwalled carbon nanotubes (MWCNTs) into poly(lactide)(PLA) using the electrospinning technique. Fiber-based nonwovens with 0.2, 0.5, 1, and 3 wt% of MWCNTs were characterized regarding conductivity, morphology, thermal, and mechanical properties. It was confirmed that an increase of the MWCNTs content does not influence the increase of the material conductivity, since the conductivity was 170 ohm sq−1 for all composites. Scanning electron microscopy and transmission electron microscopy analyses revealed that smooth and beadless fibers were obtained, but also average diameters of composite nanofibers decreased with the increase of the MWCNTs content. Differential scanning calorimetry analysis showed that the presence of MWCNTs in the PLA matrix had a significant influence on the crystallization behavior of PLA nanofibers, because the decrease in crystallization temperature ( Tc) was detected. Also, the incorporation of MWCNTs into PLA fibers affected the melting process, enabling the generation of α′ form, while had no influence on ordered α crystal. The enthalpy of composite degradation decreased, because MWCNTs are well-known for good heat conductivity, and with that the second step of degradation slowed down, as it was confirmed by thermogravimetric analysis. The addition of MWCNTs improved mechanical properties of composite fibers and caused the increase of both elasticity and tensile strengths of nanofibers.

Pyrolysis behavior of Asian lacquer film in the presence of carbon nanotubes with potential application as a new sampling method

This study aims to report the possibility of applying a sampling method using a carbon nanotube–based sampling tool for pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) to qualitative analysis of Asian lacquer. This sampling tool comprises multiwalled carbon nanotubes (MWCNTs) and emulates the adhesive mechanism of geckos. To apply this sampling method to lacquer-containing archaeological samples, the films of Toxicodendron vernicifluum, T. succedaneum and Gluta usitata, which are East Asian lacquers, were subjected to Py–GC/MS analysis. Similar to the conventional Py–GC/MS, the pyrolysis product characteristics of the three lacquer films were detected. However, compared with conventional Py–GC/MS, a difference was observed in the peak intensities of several pyrolyzates; this difference revealed the compositional change of pyrolyzates. To investigate the compositional change of pyrolyzates in detail, the T. vernicifluum film was analyzed by Py–GC/MS in the presence of MWCNTs, and the pyrolysis mechanism of T. vernicifluum film was discussed. The results suggest that MWCNTs promote side-chain cleavage and hydroxyl-group removal and alkylcatechols decompose into alkylbenzenes via alkylphenols.

Synergistic effects of nanoparticles and surfactants on n-decane-water interfacial tension and bulk foam stability at high temperature

The synergistic effects of nanoparticles and surfactants on decane-water interfacial tension, and bulk foam stability at high temperature was investigated in this study. The interfacial properties were determined using a spinning drop interfacial tensiometer while the foam stability was evaluated from the normalized foam height. The extent of interaction between nanoparticles and surfactants was estimated from the hydrodynamic nano-aggregate sizes and zeta potential values. The foam microscopic images and the bubble morphology were examined to elucidate the mechanisms of foam stabilization by nanoparticles. Results clearly showed that nanoparticles-Triton X-100 mixed system demonstrated the smallest aggregate sizes in bulk solution and considerable reduction in water/n-decane interfacial tension. Significant reduction in interfacial tension and increased foam stability occurred due to electrostatic interaction between the charged surfaces of the nanoparticles and surfactant head-groups. However, influence of electrostatic attraction was found to be dominant over the influence of electrostatic repulsion in promoting foam stability and reducing interfacial tension. The most stable foam was generated by titanium dioxide (TiO2) nanoparticles and cetyltrimethylammonium, bromide (CTAB), while the least stable foam was generated in presence of multi-walled carbon nanotubes and triton X-100. Possible reasons and mechanisms for these observations were suggested. The destabilizing influence of high temperature on foam stability was significant, however, CTAB-foam stability increased by 160% and 440% in presence of silicon dioxide (SiO2) and TiO2 nanoparticles at 80 °C. This phenomenon can be attributed to the moderate adsorption and aggregation of surface-active complex at the gas-liquid interface of the foam and Plateau borders.

(Invited) Tuning the Electrocatalytic Activity of Fe Phthalocyanine Via Axial Ligation to Multiwalled Carbon Nanotubes and Via Ligand Substitution: Electrochemistry of l-Cysteine and l-Cystine

Multiwalled carbon nanotubes (MWCNTs) are excellent platforms for the fabrication of active electrodes for electrocatalysis and electrochemical sensors [1], especially by chemical modification with molecules of known activity. We have studied the electrocatalytic activity of hybrid electrodes containing Fe-phthalocyanine (FePc) axially linked to carbon nanotubes and tested these electrodes for l-cysteine oxidation and l-cystine reduction. It is important to remark that the l-cysteine/l-cystine is a biological relevant redox couple that plays a very important role in many living systems. We have compared the electrocatalytic activity of pristine multi-walled carbon nanotubes and functionalized with –COOH, –NH2groups (MWCNT-p, MWCNT-c and MWCNT-a). These MWCNTs were chemically modified with iron phthalocyanine (FePc). These hybrid systems were characterized using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and AFM. The Fe(II)/(I) and Fe(III)/(II) redox processes of the surface confined FePc are slightly affected by the presence of MWCNTs. The activity for both reactions increases substantially by the presence of modified MWCNTs essentially by an area effect. However, when the currents are normalized by the amount of active sites estimated from the surface coverages of FePc, the activities plotted versus the redox potentials give volcano-shape curves. The data for l-cysteine oxidation fits well on a volcano correlation published previously [1] using several metal phthalocyanines and metal porphyrins (see Figure down below). This shows once more that a Mz+/M(z-1)+redox potential value does exist for which a maximum catalytic activity is observed and is an excellent reactivity descriptor for these complexes, as observed for other reactions. The reactivity trends do not change after the incorporation of FePc to MWCNTs with different chemical functionalities. Acknowledgements The authors are grateful to Fondecyt Projects 1140199, 1181037, Nucleo Milenio RC 120001. Fondecyt Postdoctoral Project 3150271 and Conicyt Scholarships M.P.O. 21130168.Fondequit, EQN160036. References E. Banks, R. G. Compton, Analyst,131(2006) 15-21.A. Gutierrez, J.F. Silva, F.J. Recio, S. Griveau, F. Bedioui, C.A. Caro, J.H. Zagal, Electrocatalysis, 5 (2014) 426–437. Figure 1

Nanocomposites based on low density polyethylene filled with carbon nanotubes prepared by high energy ball milling and their potential antibacterial activity

AbstractLow density polyethylene (LDPE) based nanocomposites containing multi‐walled carbon nanotubes (MWCNTs) were prepared by a two‐step process consisting of a pre‐mixture using high energy ball milling (HEBM) and subsequent hot pressing. The effects of ball milling and the presence of the MWCNTs on some physical properties of the materials and the antimicrobial efficiency against DH5α Escherichia coli were studied. Fourier transform infrared spectroscopy revealed that the polymer structure did not change in the final materials after the addition of MWCNTs and mixing. Differential scanning calorimetry showed small differences in the LDPE thermal behavior as a function of the type of material due to small changes in the polymer crystallization. This result was mainly ascribed to the milling process rather than to the incorporation of the MWCNTs. The presence of 1% by weight of the nanofiller increased the rigidity and hydrophobicity of the nanocomposites with respect to neat LDPE. This effect was explained by the preferential location of the MWCNTs in the surface of the material as the main factor decreasing the polar contribution to the surface free energy. A correlation between hydrophobicity, biofilm development and the shape and size of DH5α E. coli was observed, indicating that the presence of MWCNTs leads to a biocide effect by decreasing cell adhesion and changing its metabolism. © 2019 Society of Chemical Industry

NaNO3 sensing based on microfiber coated with multi-walled carbon nanotubes

Sodium nitrate (NaNO3) refractive index sensor was proposed and demonstrated by using a microfiber structure, which was coated with multi-walled carbon nanotubes (MWCNTs). In the proposed sensor, we used a flame brushing technique to fabricate microfiber and drop coating method for coating of MWCNTs thin layer. It is observed that the change of the spectrum’s output power and peak wavelength are more obvious with the coating. The presence of MWCNTs on the surface microfiber works as passive cladding and influence the light propagation through the fiber. The sensitivity and resolution of the sensor has reached 1.015 dB/% and 0.008%, respectively.