Aligned Nanotubes Research Articles

Nanotube Alignment Mechanism in Floating Evaporative Self-Assembly.

The challenge of assembling semiconducting single-wall carbon nanotubes (s-SWCNTs) into densely packed, aligned arrays has limited the scalability and practicality of high-performance nanotube-based electronics technologies. The aligned deposition of s-SWCNTs via floating evaporative self-assembly (FESA) has promise for overcoming this challenge; however, the mechanisms behind FESA need to be elucidated before the technique can be improved and scaled. Here, we gain a deeper understanding of the FESA process by studying a stationary analogue of FESA and optically tracking the dynamics of the organic ink/water/substrate and ink/air/substrate interfaces during the typical FESA process. We observe that the ink/water interface serves to collect and confine the s-SWCNTs before alignment and that the deposition of aligned bands of s-SWCNTs occurs at the ink/water/substrate contact line during the depinning of both the ink/air/substrate and ink/water/substrate contact lines. We also demonstrate improved control over the interband spacing, bandwidth, and packing density of FESA-aligned s-SWCNT arrays. The substrate lift rate (5-15 mm min-1) is used to tailor the interband spacing from 90 to 280 μm while maintaining a constant aligned s-SWCNT bandwidth of 50 μm. Varying the s-SWCNT ink concentration (0.75-10 μg mL-1) allows the control of the bandwidth from 2.5 to 45 μm. A steep increase in packing density is observed from 11 s-SWCNTs μm-1 at 0.75 μg mL-1 to 20 s-SWCNTs μm-1 at 2 μg mL-1, with a saturated packing density of ∼24 s-SWCNTs μm-1. We also demonstrate the scaling of FESA to align s-SWCNTs on a 2.5 × 2.5 cm2 scale while preserving high-quality alignment on the nanometer scale. These findings help realize the scalable fabrication of well-aligned s-SWCNT arrays to serve as large-area platforms for next-generation semiconductor electronics.

Aligned diphenylalanine nanotube–silver nanoparticle templates for high‐sensitivity surface‐enhanced Raman scattering

AbstractSelf‐assembly offers potential routes for large‐scale, rapid, and cost‐effective surface‐enhanced Raman scattering (SERS) substrate designs. Here, a highly sensitive SERS template is reported, which utilizes aligned diphenylalanine nanotubes to form a dense packing arrangement of plasmon‐active silver nanoparticles. The template is stable under high laser illumination with a power density of ~6.25 MW/cm2 in comparison to only silver nanoparticles and enables picomolar and femtomolar probe molecule concentrations to be probed, indicative of single‐molecule SERS detection.

Dispersion and alignment quantification of carbon nanotubes in a polyvinyl alcohol matrix

In recent years, due to their high specific mechanical properties, polymer matrix composites have been widely used. In particular, carbon nanotubes have been used as reinforcement because of their exceptional properties. In this work, the degree of dispersion and alignment of multiwalled carbon nanotubes into polyvinyl alcohol was quantified, which is a key information to optimize the mechanical properties of composites. For the dispersion of the multiwalled carbon nanotubes into the solution, a magnetic stirring and ultrasonic agitation were used. Finally, the mixture was dried to obtain a multiwalled carbon nanotubes reinforced polymer. The composites were mechanically stretched to obtain sheets with multiwalled carbon nanotubes aligned in the stretching direction. The layers obtained were prepared for transmission electron microscopy analysis. A dispersion quantification method based on the statistical distribution of horizontal and vertical separation distance between carbon nanotubes was used; a lognormal distribution was obtained. The angle of carbon nanotubes with respect to the stretching direction was used to quantify the alignment degree of carbon nanotubes. The bulk mechanical properties of the composites were measured by nanoindentation test; tensile test allowed to measure the mechanical properties of the composites in both the stretching and perpendicular directions to the stretching direction. Multiwalled carbon nanotubes showed a good dispersion and alignment degree and this, in conjunction with stretching, produced a high increase of both the stiffness and strength in the stretching direction, which allowed an increment of the mechanical properties measured by nanoindentation test; the best properties of the composites were reached with 0.5 wt% of MWCNTs.

High molar mass amphiphilic block copolymer enables alignment and dispersion of unfunctionalized carbon nanotubes in melt-drawn thin-films

To extensively control the nanofiller arrangement (location, orientation, shape) is still a bottleneck for multi-wall carbon nanotube (MWCNT) nanocomposites. Here, we demonstrate simultaneous control of alignment (orientation) and dispersion (location) of pristine, i.e., unfunctionalized MWCNTs using a high molar mass (HMM) amphiphilic block copolymer (BCP). We tested whether a HMM BCP in a selective solvent (i) disperses MWCNTs (ii) disperses MWCNTs by similar mechanisms to low molar mass BCPs and (iii) is melt-drawable to align the well dispersed MWCNTs. The dispersibility of MWCNTs within poly(styrene)-block-poly(2-vinylpyridine) (PS-b-P2VP) (M¯w≈500kg/mol) and its homopolymers in (non-)selective solvents was investigated by sedimentation experiments, transmission electron microscopy and visible/near-infrared spectroscopy. Through BCP micelle mediated steric stabilization, HMM PS-b-P2VP led to a highly stable MWCNT dispersion, which is explained in two simple graphical models. Using the melt-drawing technique, the well dispersed MWCNT/PS-b-P2VP dispersion was processed into a nanocomposite with a high degree of MWCNT alignment and dispersion. HMM BCPs are of significance for structural MWCNT/polymer nanocomposites, typically containing HMM polymers.

Investigation of microcombing parameters in enhancing the properties of carbon nanotube yarns

Microcombing has been reported as a novel processing approach for reducing waviness and improving alignment of carbon nanotubes (CNTs), which effectively enhances the performance of materials made from CNT sheets. In this study, we have systematically investigated the effects of microcombing parameters on the properties of CNT yarns. It is found that the electrical and mechanical properties of CNT yarns first improved with increasing degree of microcombing and then degraded with over-combing. At the optimum degree of microcombing, the electrical conductivity, tensile strength, and Young's modulus of the CNT yarns were improved to 140%, 140%, and 230%, respectively, over those of uncombed yarns. The enhanced yarn properties were resulted from reduced nanotube waviness, improved CNT alignment and denser packing structure, which led to a more uniform yarn structure. On the other hand, over-combing degraded structural uniformity, resulting in lower electrical and mechanical properties. These observations are expected to help with future selection of microcombing parameters for producing high-quality CNT yarns and polymer-CNT composite yarns for superior electrical and mechanical properties.

Strong and Broadly Tunable Plasmon Resonances in Thick Films of Aligned Carbon Nanotubes.

Low-dimensional plasmonic materials can function as high quality terahertz and infrared antennas at deep subwavelength scales. Despite these antennas' strong coupling to electromagnetic fields, there is a pressing need to further strengthen their absorption. We address this problem by fabricating thick films of aligned, uniformly sized semiconducting carbon nanotubes and showing that their plasmon resonances are strong, narrow, and broadly tunable. With thicknesses ranging from 25 to 250 nm, our films exhibit peak attenuation reaching 70%, ensemble quality factors reaching 9, and electrostatically tunable peak frequencies by a factor of 2.3. Excellent nanotube alignment leads to the attenuation being 99% linearly polarized along the nanotube axis. Increasing the film thickness blueshifts the plasmon resonators down to peak wavelengths as low as 1.4 μm, a new near-infrared regime in which they can both overlap the S11 nanotube exciton energy and access the technologically important infrared telecom band.

Alignment of carbon nanotubes in bulk epoxy matrix using a magnetic-assisted method: Solenoid magnetic field

Alignment of multi-walled carbon nanotubes (MWCNTs) in a bulk epoxy matrix was studied using a magnetic-assisted method. In this study, the applicability of solenoid magnetic field was compared to that of static magnetic field, which has recently been published. It has been found that solenoid magnetic field is able to provide better alignment of MWCNTs due to the uniform magnetic field along the axis of solenoid. Remarkable improvements were achieved in the mechanical properties of aligned MWCNT-reinforced epoxy composites. Alignment of MWCNTs was clearly observed in all regions of the composites by scanning electron microscopy and transmission electron microscopy.

Three-dimensional texture analysis of aligned carbon nanotube structures

The alignment of different carbon nanotube (CNT) structures has been studied extensively using varying techniques. Most of these techniques however do not present a true three-dimensional (3D) representation of the orientation of the material. In this work, the orientation distribution functions obtained from X-ray pole figures for different CNT structures (vertically aligned CNT arrays, randomly orientated buckypaper and horizontally aligned CNT sheets) are presented. This technique is also used to examine the effects of solvent densification and stretching on the alignment of CNT sheets. It has been demonstrated that depending on the solvent used for densification, the alignment achieved varies as the elongation is increased. The physical properties of CNT sheets are shown to depend on the alignment and solvent used for densification. The most aligned CNT sheets densified with acetone and ethanol reveal an increase in tensile strength of 140% and 58% respectively over unaligned sheets.

Surface-charge effects on the electro-orientation of insulating boron-nitride nanotubes in aqueous suspension

The alignment of hexagonal boron-nitride nanotubes (BNNTs) in aqueous KCl solutions under spatially uniform electric fields was examined experimentally, using direct optical visualization to probe the orientation dynamics of individual BNNTs for different electric-field frequencies. Different from most previously studied nanowires and nanotubes, BNNTs are wide-bandgap materials which are essentially insulating at room temperature. We analyze the electro-orientation of BNNTs in the general context of polarizable cylindrical particles in liquid suspensions, whose behavior can fall into different regimes, including alignment due to Maxwell-Wagner induced dipoles at high frequencies, and alignment due to fluid motion of the electrical double layer around the particles at lower frequencies. For BNNTs, the variation of the crossover frequencies in the electro-orientation spectra was studied in electrolytes of different conductivity. The effect of BNNT surface charge on electro-orientation was further studied by changing the pH of the aqueous solution. We find that the electric-field alignment of the BNNTs in the low-frequency regime is associated with the charging and motion of the electrical double layer around the particle. However, as BNNTs are non-conducting particles, the reasons for the formation of the electrical double layer are likely to be different than that of conducting particles. We discuss two possible mechanisms for the double-layer formation and alignment of 1D dielectric particles, and make comparison to those for the more commonly studied conducting particles.

Vertically oriented ZrO2[sbnd]TiO2[sbnd]Nb2O5[sbnd]Al2O3 mixed nanopatterned bioceramics on Ti6Al7Nb implant assessed by laser spallation technique

Recently, reports on the fabrication of nonstructural configuration have generated scientific interest due to increased awareness of the oxide nanotubes in the biomedical implant field and other industrial approaches. Here, highly ordered ZrO2TiO2Nb2O5Al2O3 nanotube arrays were grown by physical vapor deposition (PVD) of a zirconium layer on titanium-niobium alloy implant (IMPTi67) and succeeding anodic oxidation at a constant voltage (60 V) with exposure times ranging from 30 to 300 min. To crystallize the resulting mixed oxide nanotubes, heat treatment was also applied. The nanotubes were placed in an atmospheric furnace at temperatures ranging from 450 to 800 °C for 2 h. This treatment provided a morphological evolution was strongly influenced by the anodization time, where highly aligned bamboo-shaped oxide nanotubes (161 ± 44 nm in inside diameter and ∼1 μm in length) were formed after 300 min of anodization. After annealing at temperature below 500 °C, the nano-array configuration remained stable and the average inner diameter decreased to around 40 nm. The effects of anodically fabrication time on the adhesion strength of four-phase multilayered mixed oxide nanotubes on anodized Zr/IMPTi67 surfaces assed by microscratch analysis. From the results, increasing the annealing temperature further to 800 °C fully destroyed the nanotubes and consequently the tubular arrangement was converted to a coarse grain structure. It was revealed that annealing at 450 °C for 2 h was the optimum conditions for stable nanotubular array generation, where the highest adhesion strength (shifted from 2595.59 to 2640.12 mN), microhardness (372 HV) and hydrophilicity (15 ± 1°) were recorded. It is notify that the adhesion strength of highly ordered mixed nanotubes was remarkably decreased after thermal treatment at 800 °C (1817.51 mN). Through the laser spallation analysis, the intrinsic adhesion strength of the Zr/IMPTi67 interface was found to be at 63 MPa, while the first stages of failure occurred at a stress state of 35 MPa. The adhesion of the film with the tubular structure proved to have a significantly larger adhesion strength of 246 MPa for the complete failure and 203 MPa for incipient stages of spallation. The considered surface modification can be an effective step in determining the interface strength between biomedical implants and the nanostructured coatings.

Aligned MWNT channels in free standing polymer nanocomposite as an electrode for Li-ion battery

The investigation and development of flexible power sources has motivated to develop flexible, light weight, binder free, and current collector free electrodes for lithium ion batteries. We have therefore investigated the alignment and pattern of multiwall carbon nanotube (MWNT) channels in polystyrene (PS) matrix using magnetic field (5 kOe) for lithium ion storage and transport. In the presence of magnetic field, anisotropic MWNTs rotate towards the direction of the magnetic field and stabilized due to its magnetically susceptible nature. MWNTs suspended in PS were trapped and then aligned into the direction of the applied field. The alignment of MWNT channels was optimized by Raman spectroscopy and scanning electron microscopy. The charging–discharging capacity and rate capability were found to be increased for aligned MWNT/PS nanocomposite electrodes.

(Invited) Plasma Synthesis of Conductive Carbon Based Nanomaterials

Nanomaterials, such as nanocomposites, nanorods, nanotubes and graphenes, are nowadays almost past the title “novel materials”, they have been widely investigated and used as either promising or already proven materials for various applications ranging from electronics and black body coatings to fuel cells and supercapacitors (1). Such advanced nanomaterials, independently of their chemical composition, are also used for the delivery of therapeutic agents, including biomolecules targeting disease sites, for bioimaging, or in general for biomedical engineering (2). Besides the production of CBNs by exfoliation, epitaxial growth, CVD processes, and many other methods, an important method nowadays concerns the use of plasmas. In general, plasma based processes are widely used for technological applications (3). They are employed in microelectronics (4), or for example for the deposition of functional coatings and nanosystems (5). In particular low temperature reactive plasmas with their distinctive non equilibrium character provide an excellent tool for the production of novel CBNs. They are nowadays widely used for the deposition of aligned nanotube carpets, nanowalls, the synthesis of graphene, and self-standing graphene, for the controlled production of nanoparticles and for example for the manufacturing of highly porous structured surfaces (6-10). Differences in the morphology of plasma produced CBNs are caused sometimes by a small changes of the process parameters, like small variations in pulse frequency (7) or temperature (6, 11). The control and the understanding of the plasma is therefore essential in order to control the synthesis of the targeted materials. This requires enhanced efforts in plasma modelling and plasma diagnostics. This contribution focusses on the plasma based production of different kinds of conductive carbon based nanomaterials in particular on the production of carbon nanotubes, nanoparticles and nanowalls or free standing graphene. A common denominator of these materials concerns –besides their conductivity and their excellent mechanical characteristic - their large specific surface area a factor that is in particular important for applications in the field of biosensors. We will discuss in this presentation different plasma based synthesis methods. This discussion will include some critical questions concerning the importance of catalysts for the production of CBNs as well as the role of different sample pretreatment methods for the outcome of plasma based synthesis experiments. The synthesis of the different carbon materials is monitored during their growth by means of in-situ Raman-spectroscopy. A further ex-situ material analysis is performed by means of Near Edge X-ray Absorption Fine Structure Spectroscopy (NEXAFS), XPS and electron microscopy. An important aspect for bioengineering applications is related to the functionalization of the CBNs which is essential for the coupling of biomolecules to sensor surfaces. We will here report about plasma based functionalization methods and in particular about the correlation between the plasma characteristics (determined by plasma mass spectroscopy, electron density measurements, in situ FTIR) and the resulting surface functionalities. Acknowledgments: This work was supported by CNRS Défi Interdisciplinaire NANO2013, ANR PlasBioSens, APR Capt’Eau and MEP Flexible. We gratefully acknowledge also HZB, Berlin, Germany, for the allocation of the beam time. References (1) V. A. Krivchenko, S. A. Evlashin, K. V. Mironovich, N. I. Verbitskiy, A. Nefedov, C. Wöll, A. Ya. Kozmenkova, N. V. Suetin, S. E. Svyakhovskiy, D. V. Vyalikh, A. T. Rakhimov, A. V. Egorov & L. V. Yashina, Scientific Reports (Nature) 2013, 4, 3. (2) C. Cha, Su Ryon Shin, N. Annabi, M.R. Dokmeci, A. Khademhosseini, ACS Nano 2013, 7, 2891. (3) S Samukawa. et al (2012) (Plasma roadmap) J. Phys. D: Appl. Phys, 45 253001. (4) D. B. Graves, Plasma processing in microelectronics manufacturing AIChE J. 1989, 35, 1. (5) K Ostrikov, and Shuyan Xu. “Plasma aided nanofabrication: from plasma sources to nanoassembly”, (2007) Wiley-vch Verlag GmbH&Co. Weinheim, Germany. (6) E Tatarova, A Dias, J Henriques, A M Botelho do Rego, A M Ferraria, M V Abrashev, C C Luhrs, J Phillips, F M Dias, C M Ferreira, J. Phys. D: Appl. Phys. 2014, 47 385501. (7) J. Berndt, E. Kovačević, I. Stefanović, O. Stepanović, S. H. Hong, L. Boufendi, J. Winter, Contrib. Plasma Phys. 2009, 49, 107. (8) R. Ion, S. Vizireanu, C. Luculescu, A. Cimpean, G. Dinescu. Journal of Physics D: Applied Physics, 2016, 49,17. (9) P.Y. Tessier, R. Issaoui, E. Luais, M. Boujtita, A. Granier, B. Anglerau, Solid State Sciences, 2009, 11, 1824. (10) M. Hiramatsu, M. Hori. Carbon Nanowalls, Synthesis and Emerging Applications, Springer Wien New York 2010. (11) T. Labbaye, A. Canizarès, M. Gaillard, T. Lecas, E. Kovacevic, Ch. Boulmer-Leborgne, T. Strunskus, N. Raimboux, P. Simon, G. Guimbretière M. R. Ammar, Appl.Phys. Let. 2014, 105, 213109.

DNA-wrapped carbon nanotubes aligned in stretched gelatin films: Polarized resonance Raman and absorption spectroscopy study

We present the study of DNA-wrapped single-walled carbon nanotubes (SWNTs) embedded in the stretched gelatin film by the polarized resonance Raman spectroscopy and visible-NIR optical absorption. The polarized dependent absorption spectra taken along and normal to the stretching direction demonstrate a comparatively high degree of the alignment of isolated SWNTs in the gelatin matrix. The analysis of Raman spectra of isolated SWNTs in the gelatin stretched films showed that the degree of the alignment of carbon nanotubes along the stretching direction is about 62%. The dependence of the peak position of G+-band in Raman spectra on the polarization angle θ between the polarization of the incident light and the direction of the stretching of films was revealed. This shift is explained by the different polarization dependence of the most intensive A and E1 symmetry modes within the G+-band. The performed studies of embedded DNA-wrapped nanotubes in the gelatin film show the simple method for obtaining the controlled ordered biocompatible nanotubes inside a polymer matrix. It can be used for manufacturing sizable flexible self-transparent films with integrated nanoelectrodes.

Correction to Shear Alignment of Bola-Amphiphilic Arginine-Coated Peptide Nanotubes.

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to Shear Alignment of Bola-Amphiphilic Arginine-Coated Peptide NanotubesIan W. Hamley*, Samuel Burholt, Jessica Hutchinson, Valeria Castelletto, Emerson Rodrigo da Silva, Wendel Alves, Philipp Gutfreund, Lionel Porcar, Rajeev Dattani, Daniel Hermida-Merino, Gemma Newby, Mehedi Reza, Janne Ruokolainen, and Joanna StasiakView Author Information Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, United Kingdom Instituto de Física, Universidade Federal de Alagoas, Maceió-Alagoas 57072-900, Brazil Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André 09210-580, Brazil Institut Max von Laue - Paul Langevin, CS 20156; 71, Avenue des Martyrs F-38042 Grenoble Cedex 9, France ESRF-The European Synchrotron, 38043 Grenoble Cedex 9, France Department of Applied Physics, Aalto University School of Science, Aalto FI-00076, Finland Department of Chemical Engineering & Biotechnology, University of Cambridge, Pembroke Street, Cambridge, CB2 3RA, United KingdomCite this: Biomacromolecules 2017, 18, 5, 1660Publication Date (Web):April 10, 2017Publication History Published online10 April 2017Published inissue 8 May 2017https://doi.org/10.1021/acs.biomac.7b00484Copyright © 2017 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views547Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (634 KB) Get e-Alerts Get e-Alerts

A simple preparation method and characterization of B and N co-doped TiO2 nanotube arrays with enhanced photoelectrochemical performance

Highly ordered TiO2 nanotube arrays (TNTA) have attracted much attention due to the excellent photocatalytic, optical and electrical properties. However, their absorption range is limited to ultraviolet (UV) spectrum only due to the wide band gap (3.2eV). One of the strategies to overcome this problem is doping with boron and nitrogen. They are produced via titanium sheet anodization and subsequent electrochemical treatment of titania in an electrolyte containing boric acid. The as-prepared B-TNTA are annealed in N2 atmosphere at 500°C for 2h to obtain B,N-TNTA. The samples are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The B,N-TNTA consist of uniform and well aligned nanotubes with an average inner diameter of 80–100nm and a length not exceeding 1μm. The photocurrent response measurements of undoped TNTA, N-doped and B,N-co-doped samples are performed under UV and visible light (Vis) illumination and a comparison is made. The obtained results show that the B,N-doping leads to remarkable photocurrent enhancement and better photocatalytic activity for methyl orange (MO) degradation due to the synergistic effects of B,N-co-doping and lower electron-hole recombination rates.

Electrochemical synthesis of aligned amorphous carbon nanotubes/TiO2 nanotubes heterostructured arrays and its field emission properties

Highly aligned amorphous carbon nanotubes/TiO2 nanotubes (a-CNTs/TiO2) arrays are synthesized by combining anodic oxidation and electrochemical deposition method. The amorphous carbon nanotubes (a-CNTs) arrays grow along the axis direction on the top of TiO2 nanotubes arrays owing to the high potential and the confined surface. The a-CNTs arrays are tightly connected with TiO2 nanotubes forming the heterostructured a-CNTs/TiO2 nanotubes arrays. Here, the novel hetero-architecture demonstrates a low turn-on field of 2.6Vμm−1 and a high current density of 14mAcm−2. The excellent field emission performance is attributed to the synergetic effects among aligned nanotubes arrays structure, high aspect ratio, desirable interface contact between a-CNTs and TiO2 nanotubes, and low work function.

Influences of matrix viscosity on alignment of multi-walled carbon nanotubes in one-dimensional confined space

The effects of matrix viscosity on alignment of multi-walled carbon nanotubes (MWCNTs) and physical properties of high density polyethylene (HDPE)/MWCNTs composite nanofibers via nanolayer coextrusion are studied. The alignment states are altered depending upon the matrix viscosity of the composite nanofibers. The morphology and nano-sized diameter of the nanofibers are observed on scanning electron microscope. To characterize the prioritized alignment and dispersion of MWCNTs in the matrix, transmission electron microscopy, polarized Raman spectra, and high resolution optical microscopy are used. It is found that the alignment of MWCNTs in higher viscosity matrix of the nanofibers is better than that in lower viscosity. The aligned MWCNTs composite nanofibers have smaller slope variations of rheological curves with increasing content of MWCNTs. In addition, the higher aligned HDPE/MWCNTs composite nanofibers exhibit higher decomposition temperature and enhanced mechanical properties. However, the poorly aligned nanofibers have higher electrical and thermal conductivities due to the easily formed three-dimensional network.

Optimization of Buckypaper-enhanced Multifunctional Thermoplastic Composites

A series of flattened-nanotube reinforced thermoplastic composites are sizably fabricated as a function of buckypaper loading. The effects of the volume fraction, nanotube alignment and length on the tensile performance of the composites are factored into a general expression. The incorporation of self-reinforcing polyphenylene resin (Parmax) into a highly aligned buckypaper frame at an optimal weight ratio boosts the tensile strength and Young’s modulus of the buckypaper/Parmax composite to 1145 MPa and 150 GPa, respectively, far exceeding those of Parmax and aligned buckypaper individually. The composite also exhibits improved thermal (>65 W/m-K) and electrical (~700 S/cm) conductivities, as well as high thermoelectric power (22 μV/K) at room temperature. Meanwhile, the composite displays a heterogeneously complex structure. The hexyl groups of Parmax noncovalently interact with the honeycomb structure of the flattened nanotube through π-stacking and CH-π interaction, correspondingly improving the dispersity of polymer on the nanotube surface and the interfacial stress transferring while the high alignment degrees of nanotube facilitate phonon and charge transport in the composites.

Strain sensing behaviors of epoxy nanocomposites with carbon nanotubes under cyclic deformation

The strain sensing behavior of multi-walled carbon nanotubes (MWCNT)/epoxy (EP) conductive composites subjected to tensile strain was studied in detail. With increasing the load to rupture, the responsivity (ΔR/R0, R0 is the original resistance, ΔR is instantaneous change in resistance) increased in a linear fashion and then began to decrease at a critical strain (εc), which was remarkably different from the thermoplastic conductive composites only with a monotonic increase of the responsivity. It was attributed to the decrease of the nanotube contact points, the increase in the gaps before εc, and the reorientation and violent alignment of nanotubes in the zones of high local deformation (after εc). In addition, when the extension-retraction cycles were applied, the values of max ΔR/R0 showed a distinct tendency with different strains around the εc. These behaviors were attributed to the competition of network destruction and reconstruction during the cyclic deformation. The mechanism of this unique sensing behavior was proposed as well.

Alignment of Ge-imogolite nanotubes in isomalt with tunable inter-tube distances

This study shows the almost perfect alignment of inorganic nanotubes (Ge-imogolite) within polyol filaments.