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Abstract: Polyacrylonitrile-based carbon fibers, embedded with single-walled carbon nanotubes have been prepared by the electrospinning technique. The as-spun nanofibers were hot-stretched in an oven to enhance the orientation and crystallinity which has been confirmed by X-ray diffraction and DSC etc. With the hot-stretched process and the introduction of SWNTs, the mechanical properties of PAN nanofibers such as the modulus and tensile strength will be enhanced correspondingly. In addition, the electrical conductivities of the PAN/SWNTs nanofiber composites were also enhanced. It was concluded that the hot-stretched nanofibers and the PAN/SWNTs nanofiber composites can be used as a potential precursor to produce high-performance carbon nanocomposites. [Copyright &y& Elsevier]

Ultrahigh power is needed beyond the state-of-the-art supercapacitors for emerging technologies. Towards this goal, nanostructured carbon materials have been extensively studied but unfortunately encountered with the difficulty in practical applications, which is largely due to their limited packing densities. In this work, we utilize a highly dense commercial activated carbon to develop high-rate nanocomposite electrodes and ultrahigh-power supercapacitors by compositing activated carbon with carbon nanomaterials, including zero-dimensional carbon black, one-dimensional carbon nanotube, and two-dimensional graphene. Enabled by the mixed packing (forming a unique point-to-line-to-plane contact morphology), diverse electrical conduction (forming a well-interconnected three-dimensional electrical conduction network), and varied porosity (forming a well-defined hierarchical porous structure) from these multiple constituents, the optimized quaternary nanocomposite electrode possesses a good combination of facilitated electron transport and enhanced ion diffusion and thus a twofold higher rate capability (capacitance retention: 83.3% vs. 28.9% at 80 A g−1 vs. 0.5 A g−1), twofold higher power density (84.1 kW kg−1 vs. 41.9 kW kg−1), and superior high-rate cycling stability (capacitance retention: 80.2% vs. 65.9% after charge/discharge at 10 A g−1 for 30,000 cycles) than its conventional activated carbon counterpart, while its high volumetric power density (50.5 kW L−1) strengthens its practical usefulness. Our research represents a novel approach to fabricate commercially available materials into practically useful ultrahigh-power supercapacitors at low cost, which may also be employed as a universal strategy to develop high-performance nanocomposites to benefit a wider range of application technologies. [ABSTRACT FROM AUTHOR]

A multi-scale "nunchaku-like" rigid-flexible-rigid structure was constructed on the CF surface using carbon nanotubes (CNTs) and polyether amines (PEA) to improve the interfacial properties of carbon fiber (CF) reinforced polymer composites. The multi-scale rigid-flexible-rigid structure not only enhanced the chemical bonding, mechanical engagement and wettability, but also balanced the modulus of the fibers and resin to achieve best match for less stress concentration. As a consequence, IFSS, ILSS and TFBT strength increased by 73.4%, 65.4% and 137.0% compared to the original composites. In addition, the composites failure behavior and the interfacial strengthening mechanism were investigated in detail. This work proposed a novel and promising strategy for the preparation of high-performance CF composite from the perspective of interfacial structure design. [ABSTRACT FROM AUTHOR]

Carboxyl-functionalized carbon nanotubes (CNTs-COOH) and the amine-functionalized carbon nanotubes (CNTs-NH 2) were incorporated into the surface sizing agent of carbon fibers respectively, for modifying the interface between the fibers and the matrix. Experimental analyses of the interfacial shear strength, flexural properties, and inter-laminar shear strength revealed the beneficial effects of the CNTs-COOH and negative impacts of the CNTs-NH 2 on the interfacial and mechanical properties of the resulting composites. These results were contrary to the effects of CNTs doped into the epoxy matrix of composites. Furthermore, a molecular dynamics simulations were performed to explore the mechanism of these performances from the viewpoint of the molecular structure, revealing that the interface between the CNT-sized carbon fibers and the epoxy was driven by multiple factors, including the CNT-epoxy interfacial binding energy (IBE), the packing density of the molecular chains, and the steric hindrance of the functionalized CNTs. According to these analyses, two kinds of functionalized CNTs showed different effects at the interface between carbon fiber and resin: the CNTs-COOH on the surface of the carbon fiber tightly bonded to the epoxy and provided effective load transfer between the matrix and fibers, whereas the agglomeration of the CNTs-NH 2 , the lower IBE between the CNTs-NH 2 and the epoxy resin, and the steric hindrance produced by amine functional groups of the CNTs-NH 2 , resulting in hardly inhibiting the crack growth of the matrix under stress. Image 1 [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • MWCNT-PDA/GO hybrid aerogels were synthesized through a viable green route. • MWCNT-PDA provided aerogels larger specific surface area and abundant active sites. • Synergistic effect of complexation and chelation determined adsorption result. • The mechanism of high adsorption capacity has been proposed and characterized. Abstract In this study, the ultra-lightweight and robust three-dimensional graphene/polydopamine modified multiwalled carbon nanotube (MWCNT-PDA) hybrid aerogels were prepared via a viable green route and applied to highly efficient heavy metal ions adsorption. No additional reducing agents were required during the molding of the hybrid aerogel, thus greatly reducing the environment pollution emissions. The MWCNT-PDA in right amounts provided the hybrid aerogels with satisfying structure stability and effectively prevented the stacking of GO sheets, as well as exposed more active sites to improve the adsorption of heavy metal ions. Benefiting from the large specific surface area, porous structure and competent active sites, the resulting hybrid aerogels showed superior adsorption performance for heavy metal ions, and the saturated adsorption capacities were as large as 318.47 and 350.87 mg g−1 for Cu(II) and Pb(II), respectively, calculated by the Langmuir isotherm model. The research revealed that the synergistic effects of the surface complexation and chelation between active sites in hybrid aerogels and heavy metal ions were the dominant adsorption mechanisms. High adsorption capacity and easy separation from water after adsorption make the hybrid aerogels an ideal choice for heavy metal ions treatment in practical application. [ABSTRACT FROM AUTHOR]

A novel 3D nanomaterial (MWCNT-PDA-POSS) with bump structure was prepared by combining multi-walled carbon nanotubes (MWCNTs) and polyhedral oligomeric silsesquioxanes (POSS) via mussel-inspired chemistry. A two-step process was used for preparation of MWCNT-PDA-POSS, and the potential chemical reaction between carboxyl-functionalized MWCNT (MWCNT-COOH), polydopamine (PDA) and amino-functionalized POSS (POSS-NH 2 ) was investigated. Furthermore, the unique bump structure of the MWCNT-PDA-POSS was observed. As nanofillers in the resin matrix, the bump structure can provide higher specific surface area while some unreacted catechol functional groups of PDA would participate in the cross-linking reaction of epoxy resin, leading to the interface strengthening between the MWCNTs and resin matrix. Therefore, the MWCNT-PDA-POSS resulted in the significantly improved compressive performances compared to the neat epoxy, and POSS-NH 2 and MWCNT-COOH reinforced ones, which exhibited potential application in the multi-scale reinforced composites. [ABSTRACT FROM AUTHOR]

An intractable problem has been revealed that the resin matrix viscosity was rising obviously after the addition of solid nano-fillers involving all kinds of surface chemical modification, causing the degraded processing properties and defective structure in the polymer composites. Therefore, the application of nano-fillers in the filament winding processing of carbon fibre composites is severely limited, in which low initial viscosity of resin matrix is required under processing temperature to ensure the impregnation of the resin to fibres. In this study, a kind of liquid-like MWCNT reinforcements (L-MWCNTs) were fabricated and explored as nano-reinforcements for T1000 carbon fibre filament winding composites. Some technical means such as transmission electron microscopy and atomic force microscopy were used to analyze the dispersion state of L-MWCNTs and interfacial interaction of the resulting composites. The mechanical properties of carbon fibre filament winding composites were characterized through Naval Ordinance Laboratory-ring burst tests and interlaminar shear strength (ILSS) tests. The results showed that the L-MWCNTs can be uniformly dispersed in an epoxy matrix without deteriorating good processing performances for the filament winding composites. The resin matrix containing the L-MWCNTs exhibited a lower surface energy and better interface bonding with T1000 carbon fibre than that of the neat epoxy. Through the addition of 6 wt% L-MWCNTs, an enhancement of 15% in tensile strength, 28% in ILSS, as well as 14.8 °C in T g was realized for T1000 carbon fibre composites. The L-MWCNTs can exhibit important application values as a nano-reinforcement for improving interfacial, mechanical and thermal properties of the existing carbon fibre composites. [ABSTRACT FROM AUTHOR]

A pelote-like hybrid particle was fabricated via self-assembly of PA microparticles and epoxy functionalized carbon nanotubes (MWNTs-EP), and the effects of interlayer films containing self-assembled hybrid particles (PA-MWNTs-EP) on interlaminar shear property and fracture toughness of CFRP composites were studied. The spontaneous self-assembly was ascribed to electrostatic adsorption between MWNTs-EP and PA microparticles. Remarkable improvements in interlaminar shear strength (ILSS) and mode I fracture toughness (G IC ) of the CFRP composites were achieved with the incorporation of interlayer films containing PA-MWNTs-EP. The pelote-like microscopic structure of PA-MWNTs-EP was considered to provide extraordinary synergy of one-dimensional MWNTs-EP and three-dimensional PA microparticles through establishment of multi-scale interface based on chemical bonding. A schematic model of stress transfer was proposed to illustrate the effects of multi-scale interface established among PA, MWNTs-EP, epoxy matrix, and carbon fiber in the interlaminar region of interlayer-toughened CFRP composites. [ABSTRACT FROM AUTHOR]

Abstract: Scaffolds with both macro- and nanoscale structures have shown promise in tissue engineering; however, their mechanical properties are not satisfactory for load-bearing bone regeneration. In this study, calcium phosphate-coated multiwalled carbon nanotubes (MWCNTs-CaP) were developed to reinforce macroporous poly(L-lactide) (PLLA) scaffolds with nanofibrous pore walls. The scaffolds were prepared using a phase separation/particle-leaching method. One-dimensional MWCNTs-CaP were prepared via phosphorylation and mineralization. The addition of the MWCNTs-CaP did not affect the nanofibrous pore walls of the resulting PLLA scaffolds. In comparison with pure PLLA scaffolds, the compressive properties of PLLA/MWCNTs-CaP composite scaffolds were significantly improved, indicating their potential in bone regeneration applications. [Copyright &y& Elsevier]

Abstract: A new core-shell coaxial carbon nanofibers web (C-CNFW), exhibiting high carbon purity (without any binders), structural integrity, enhanced stability under different current loads, long cycling life, large reversible capacity (over 520mAh g−1), excellent capacity retention and good rate capability, is fabricated by coaxial electrospinning and subsequent carbonization. It is envisaged that the superior electrochemical properties of C-CNFW will make it a promising candidate for the anode material of high-power lithium-ion batteries (LIBs), owing to the unique combinative effects of core carbon material from mineral oil and sheath carbon material from PAN. [Copyright &y& Elsevier]

Abstract: A facile approach of magnifying the functional groups on the multi-walled carbon nanotubes (MWNTs) was developed by introducing the bridge of poly (acryloyl chloride) (PACl). Special functional groups could be further generated by the reaction of acyl chloride groups. Accordingly, the MWNTs with magnified epoxy groups (MWNTs–epoxy) were prepared, and its reinforcement for epoxy composites was studied. The structural destruction of acid treated MWNTs was testified by Raman spectra. The MWNTs–epoxy was characterized by Fourier Transform Infrared (FT-IR), Differential Scanning Calorimetry (DSC), Transmission Electron Microscopy (TEM) and Thermo-Gravimetric Analysis (TGA). The properties of nanocomposites were measured by Dynamical Mechanical Analysis (DMA), tensile testing and Scanning Electron Microscopy (SEM). Because of the magnification of functional groups and the higher interfacial adhesion between MWNTs–epoxy and epoxy matrix, the composites exhibited the enhancement of mechanical properties at lower content (0.1–1.0wt.%). Tensile strength and tensile modulus were increased nearly 45% and 90%, respectively. [Copyright &y& Elsevier]

Abstract: A silica–polymer–carbon nanotube hybrid was prepared in which the nanotubes were encapsulated by poly(3-acrylaminopropylsiloxane) with silica nanospheres on the polymer surface. First, highly reactive poly(acryloyl chloride) (PAC) was grafted onto the nanotubes through the reaction of side acyl chloride groups with hydroxyl groups present on the surface of acid–oxidized nanotubes. Second, reacting 3-aminopropyltriethoxysilane with the grafted PAC through the reaction between amino and acyl chloride groups, siloxane-containing sub-grafts were introduced onto the primary PAC grafts. Third, silica nanospheres were covalently linked to the sub-grafts by condensation to form a nanotube–polymer–silica hybrid. Each intermediate structure was confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy (TEM). TEM observation revealed a nanostructure in which the nanotube was encapsulated with a polymer layer bearing silica nanospheres on its surface. [Copyright &y& Elsevier]

[Display omitted] • Conductive films are obtained by introducing CNT into polyorganphosphazene (POPP) or polyester. • POPP/CNT film promotes osteogenic differentiation of BMSCs more efficiently than polyester/CNT film. • Differentiation potential of BMSCs cultured on conductive films is promoted with exposure to electrical stimulation (ES). • Synergistic promotion on osteogenesis is achieved using the combination of POPP/CNT substrate and ES. Bone is an electrically responsive tissue, so electroactive materials that can deliver electrical cues to bone are helpful for enhancing regeneration under electrical stimulation (ES), and conductive materials are crucial in ES transmission to determine osteogenesis. Compared with polyesters, biodegradable polyorganophosphazenes (POPPs) show superiority in the field of bone tissue engineering thanks to their rich phosphorus/nitrogen contents, suggesting that the combination of POPPs-based conductive substrates with ES may achieve synergistic enhancements on osteogenesis. Herein, conductive composite films were fabricated by blending poly[(alanine ethyl ester)-(glycine ethyl ester)]phosphazene (PAGP) with carbon nanotubes (CNTs). After surface modification with polydopamine (PDA), bone marrow mesenchymal stromal cells (BMSCs) were cultured on the films under ES, using the cells cultured on conductive films composed of poly(L-lactide) (PLLA) and CNTs as controls. The BMSCs on PAGP/CNT films demonstrated significantly faster proliferation rates and stronger osteogenic differentiation potentials than those on PLLA/CNT films, while cell attachments on the two PDA-coated substrates were similar. Under appropriate ES, further increases in the expressions of osteogenic markers as alkaline phosphatase, collagen I and calcium deposition were identified in comparison with the cases without ES. The contributions of the osteocompatible POPPs, the substrate conductivity and the ES treatment to enhanced osteogenesis suggested new strategies for the design of bone repair materials. [ABSTRACT FROM AUTHOR]

• The Sb 2 S 3 @N-C/graphene composite aerogel was firstly designed and prepared as an anode for SIBs. • The composite aerogel dramatically exhibited structural stability owing to PDA coating layer. • The unique Sb 2 S 3 @N-C nanotubes encapsulated by graphene possessed rapid Na+ transport kinetics. • The composite anode materials with ingenious structure displayed superior cycling reversibility. The Sb 2 S 3 anode materials with high theoretical capacity were troubled by their sluggish electrochemical kinetics and huge volume expansion in sodium-ion batteries. Herein, we firstly designed a unique Sb 2 S 3 @nitrogen-doped carbon (Sb 2 S 3 @N-C) nanotube encapsulated by porous graphene aerogel to solve the above technical barrier. The composite aerogel with ingenious structure was creatively designed by coating polydopamine (PDA) onto the Sb 2 S 3 nanorods. The PDA was not only a precursor of nitrogen-doped carbon (N-C) layer adjusting volume change of Sb 2 S 3 during storage Na+ but also acted as a reducing agent assisting to create graphene aerogel. Moreover, the formation of unique Sb 2 S 3 @N-C coaxial nanotubes was facilitated by the N-C layer, which triggered the strong interaction between the Sb 2 S 3 and graphene to maintain structural integrity. Importantly, the composite aerogel synergized the superior electrical conductivity, abundant porous channels, and excellent electrochemical reactivity into one. As a result, the optimized anode exhibited high reversible capacity, superior rate capability, and impressively cycling stability. Furthermore, the full cell was constructed from the optimized composite aerogel anode and Na 3 V 2 (PO 4) 3 cathode, exhibiting a high reversible capacity of 388 mA h g−1 at 0.1 A g−1 with a remarkable energy density of 189 Wh kg−1. [ABSTRACT FROM AUTHOR]

Synergetic strengthening effects of epoxy grafted polyurethane (EP-PU) and aminated MWCNTs (MWCNTs-NH 2) on mechanical performance of EP-based composites at 77 K were systematically investigated using the tested results at room temperature (RT) as comparisons. EP-PU was successfully synthesized by controlling the reaction between –OH in EP and –NCO in PU prepolymer, which showed the advantages of relatively low viscosity and outstanding chemical miscibility with EP matrix. The most obvious enhancements were achieved with contents of 30 wt% EP-PU and 0.2 wt% MWCNTs-NH 2 in tensile, flexural, impact and K IC fracture toughness properties of EP composites as well as flexural properties and interlaminar shear strength (ILSS) of carbon fiber (CF)/EP composites at both RT and 77 K, which confirmed the synergetic strengthening effects of EP-PU and MWCNTs-NH 2. Specifically, K IC fracture toughness of EP composites and ILSS of CF/EP composites at 77 K were enhanced by 26.0 and 31.4%, respectively, compared with the corresponding neat composites. The EP-PU component showed β or γ relaxation behavior at cryogenic condition and existed in form of scattered micro-spheres in cured EP matrix due to the phase separation. The riveting and bridging of MWCNTs-NH 2 around EP-PU micro-spheres were considered to provide extraordinary synergy on the effective stress diversion and crack propagation inhibition at cryogenic condition through establishing the chemically bonded multi-scale interface. [ABSTRACT FROM AUTHOR]