scispace - formally typeset
Search or ask a question

Showing papers on "Nanocomposite published in 2009"


Journal ArticleDOI
03 Dec 2009-ACS Nano
TL;DR: Graphene platelets significantly out-perform carbon nanotube additives in terms of mechanical properties enhancement, and may be related to their high specific surface area, enhanced nanofiller-matrix adhesion/interlocking arising from their wrinkled (rough) surface, as well as the two-dimensional geometry of graphene platelets.
Abstract: In this study, the mechanical properties of epoxy nanocomposites with graphene platelets, single-walled carbon nanotubes, and multi-walled carbon nanotube additives were compared at a nanofiller weight fraction of 0.1 ± 0.002%. The mechanical properties measured were the Young’s modulus, ultimate tensile strength, fracture toughness, fracture energy, and the material’s resistance to fatigue crack propagation. The results indicate that graphene platelets significantly out-perform carbon nanotube additives. The Young’s modulus of the graphene nanocomposite was ∼31% greater than the pristine epoxy as compared to ∼3% increase for single-walled carbon nanotubes. The tensile strength of the baseline epoxy was enhanced by ∼40% with graphene platelets compared to ∼14% improvement for multi-walled carbon nanotubes. The mode I fracture toughness of the nanocomposite with graphene platelets showed ∼53% increase over the epoxy compared to ∼20% improvement for multi-walled carbon nanotubes. The fatigue resistance resu...

2,367 citations


Journal ArticleDOI
Jiajie Liang1, Yi Huang1, Long Zhang1, Yan Wang1, Yanfeng Ma1, Tianyin Guo1, Yongsheng Chen1 
TL;DR: In this paper, the preparation of polyvinyl alcohol (PVA) nanocomposites with graphene oxide (GO) using a simple water solution processing method is reported, and efficient load transfer is found between the nanofiller graphene and matrix PVA and the mechanical properties of the graphene-based nanocompositionite with molecule-level dispersion are significantly improved.
Abstract: Despite great recent progress with carbon nanotubes and other nanoscale fillers, the development of strong, durable, and cost-efficient multifunctional nanocomposite materials has yet to be achieved. The challenges are to achieve molecule-level dispersion and maximum interfacial interaction between the nanofiller and the matrix at low loading. Here, the preparation of poly(vinyl alcohol) (PVA) nanocomposites with graphene oxide (GO) using a simple water solution processing method is reported. Efficient load transfer is found between the nanofiller graphene and matrix PVA and the mechanical properties of the graphene-based nanocomposite with molecule-level dispersion are significantly improved. A 76% increase in tensile strength and a 62% improvement of Young's modulus are achieved by addition of only 0.7 wt% of GO. The experimentally determined Young's modulus is in excellent agreement with theoretical simulation.

1,508 citations


Journal ArticleDOI
TL;DR: Preliminary experiments in chemical doping are presented and show that optimization of this material is not limited to improvements in layer morphology, and that this technology is inexpensive, is massively scalable, and does not suffer from several shortcomings of indium tin oxide.
Abstract: We report the formation of a nanocomposite comprised of chemically converted graphene and carbon nanotubes. Our solution-based method does not require surfactants, thus preserving the intrinsic electronic and mechanical properties of both components, delivering 240 ohms/square at 86% transmittance. This low-temperature process is completely compatible with flexible substrates and does not require a sophisticated transfer process. We believe that this technology is inexpensive, is massively scalable, and does not suffer from several shortcomings of indium tin oxide. A proof-of-concept application in a polymer solar cell with power conversion efficiency of 0.85% is demonstrated. Preliminary experiments in chemical doping are presented and show that optimization of this material is not limited to improvements in layer morphology.

1,005 citations


Journal ArticleDOI
TL;DR: A review of the existing studies on the permeability of gas molecules in nanocomposite materials that consist of inorganic platelet-shaped fillers in polymeric matrices is presented in this paper.

942 citations


Journal ArticleDOI
TL;DR: The prepared MMWCNT adsorbent displayed the main advantage of separation convenience compared to the present adsorption treatment and was well fitted by a pseudo second-order model.

942 citations


Journal ArticleDOI
TL;DR: In this article, a hierarchical structured sulfur−carbon (S/C) nanocomposite material was used as the high surface area cathode for rechargeable lithium batteries. But the results show that the cyclability and utilization of sulfur in the Li/S batteries have been significantly improved.
Abstract: We report herein a hierarchically structured sulfur−carbon (S/C) nanocomposite material as the high surface-area cathode for rechargeable lithium batteries. A porous carbon with a uniform distribution of mesopores of 7.3 nm has been synthesized through a soft-template synthesis method. The potassium hydroxide activation of this mesoporous carbon results in a bimodal porous carbon with added microporosity of less than 2 nm to the existing mesopores without deterioration of the integrity of the original mesoporous carbon. Elemental sulfur has been loaded to the micropores through a solution infiltration method. The resulted S/C composites with various loading level of sulfur have a high surface areas and large internal porosities. These materials have been tested as novel cathodes for Li/S batteries. The results show that the cyclability and the utilization of sulfur in the Li/S batteries have been significantly improved. The large internal porosity and surface area of the micromesoporous carbon is essentia...

831 citations


Journal ArticleDOI
05 Aug 2009-ACS Nano
TL;DR: Comparisons with model calculations indicate the important roles of nanoparticle percolation and porosity of the nanocomposites on the dielectric properties, and the calculated maximum energy densities indicate maximal extractable energy for two different particle volume fractions.
Abstract: The dielectric permittivity and electric breakdown strength of nanocomposites comprising poly(vinylidene fluoride-co-hexafluoro propylene) and phosphonic acid surface-modified BaTiO3 nanoparticles have been investigated as a function of the volume fraction of nanoparticles. The mode of binding of pentafluorobenzylphosphonic acid on the BaTiO3 particles was investigated using infrared and 31P solid-state nuclear magnetic resonance spectroscopy, and the phosphonic acid was found to form well ordered, tightly bound monolayers. The effective permittivity of nanocomposites with low volume fractions (<50%) was in good agreement with standard theoretical models, with a maximum relative permittivity of 35. However, for nanoparticle volume fractions of greater than 50%, the effective permittivity was observed to decrease with increasing nanoparticle volume fraction, and this was correlated with an increase in porosity of the spin-coated nanocomposite films. The dielectric breakdown strength was also found to decre...

762 citations


Journal ArticleDOI
TL;DR: It was proved that the chemical treatment clearly improves the ultimate properties of the nanocomposites and significant differences were reported according to the nature of the nanoparticle and amount of nanofillers used as reinforcement.

761 citations


Journal ArticleDOI
TL;DR: A review of metal-based reactive nanomaterials can be found in this paper, where some potential directions for the future research are discussed and some potential application areas are explored.

739 citations


Journal ArticleDOI
TL;DR: In this article, a review summarizes the current state of polymer composites used as dielectric materials for energy storage, focusing on materials: polymers serving as the matrix, inorganic fillers used to increase the effective dielectrics constant, and various recent investigations of functionalization of metal oxide fillers to improve compatibility with polymers.
Abstract: This review summarizes the current state of polymer composites used as dielectric materials for energy storage The particular focus is on materials: polymers serving as the matrix, inorganic fillers used to increase the effective dielectric constant, and various recent investigations of functionalization of metal oxide fillers to improve compatibility with polymers We review the recent literature focused on the dielectric characterization of composites, specifically the measurement of dielectric permittivity and breakdown field strength Special attention is given to the analysis of the energy density of polymer composite materials and how the functionalization of the inorganic filler affects the energy density of polymer composite dielectric materials

689 citations


Journal ArticleDOI
TL;DR: In this article, the authors proposed a novel nanocomposite system consisting of poly(vinylidene fluoride) and exfoliated graphite nanoplates (PVDF/xGnPs).
Abstract: Ferroelectric polymers, such as poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)), and poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) have great potential for applications in micro-electromechanical devices and high-charge storage capacitors. In order to realize these applications, it is highly desirable to substantially improve the dielectric constants of such ferroelectric polymers. Up to now, much work has focused on the preparation of 0–3-type composites based on polymers and ceramics of high dielectric constant, and the resultant composites usually possess a relatively high dielectric permittivity (about 100). Nevertheless, the high volume fraction (> 50 vol%) of ceramics, which was necessary to achieve the high dielectric constants, presents a number of limitations, in terms of high weight, low flexibility, and poor mechanical performance, as a result of the weak matrix-filler bonding and agglomeration of ceramic nanoparticles. Furthermore, most ceramics of high dielectric constant are lead-based, and potentially harmful to our health. To overcome the limitations of ferroelectric polymer/ceramic composites, very promising work has been carried out recently based on percolation theory, in which a small volume fraction of some conductive filler was added to the polymer matrix to achieve a high dielectric constant, thus preserving the mechanical flexibility of the polymer. For example, Dang et al. fabricated a new poly(vinylidene fluoride)/carbon-nanotube composite, with a percolation threshold of 8 vol%, possessing a dielectric constant of 600 (the dielectric loss value, tan d, is about 2) at 1000Hz. For a P(VDF-TrFE-CFE)/carbon-nanotube system, the dielectric constant increased from 57 to 102 (tand! 0.36) at 100Hz, by inclusion of only 2wt% (1.2 vol%) carbon nanotubes. A dielectric constant as high as 56 was observed in a PVDF/acetylene-black composite, when the acetylene-black concentration was in the neighborhood of the percolation threshold (about 1.3 vol%). Recently, Panda et al. reported that, for PVDF/Ni composites, a high effective dielectric constant of 2050 (tand1⁄4 10) at 100Hz was observed near the percolation threshold of 27 vol%. Along this line, in this communication, we propose a novel nanocomposite system consisting of poly(vinylidene fluoride) and exfoliated graphite nanoplates (PVDF/xGnPs). The xGnPs were selected as the conductive filler, because of their good electrical and thermal conductivity, high mechanical strength, and more importantly, large aspect ratio and unique layered structure with nanoscale thickness, which give advantages in the formation of a large number of parallel-board microcapacitors with low filler loading. Moreover, functional groups, such as C–O–C, C–OH, and C––O, existing on the surface of graphite nanoplates, can promote the interaction between the PVDF and the graphite nanoplates, leading to good dispersion of xGnPs in thematrix. It is well known that the homogenous dispersion of conductive fillers in a polymer matrix is a critical factor in achieving a high-performance nanocomposite. Therefore, it was expected that a much lower volume fraction of xGnP in the PVDF/xGnP nanocomposite could result in a greater increase in dielectric permittivity. xGnPs were obtained from subjecting natural graphite flakes to acidic intercalation, rapid thermal treatment, and ultrasonic powdering, in sequence (see S1 in Supporting Information). Natural graphite flakes (see S2 in Supporting Information), a naturally abundant and low-cost carbon-based material, are composed of parallel carbon layers. Carbon atoms within the graphite layers connect to each other to form six-member rings through strong covalent bonds, while the parallel carbon layers are joined together by weak van der Waals force. Such a structure makes it possible to intercalate some small molecules into the interlayer space of graphite. In the present study, natural graphite flakes were first converted to graphite intercalation compounds (GICs), through intercalation and chemical oxidation in the presence of concentrated H2SO4 andHNO3.When heated at high temperatures, because of the volatilization of the mixed acid, the GICs could be expanded up to a few hundred times along the direction perpendicular to the carbon-layer plane of the intercalated graphite, so that expanded graphite (EG), which is a worm-like material (see the scanning electron microscopy (SEM) image, shown in Fig. 1a), could be obtained. It is also important to note that some functional groups could be introduced to the graphite during the preparation of the GICs and EG. After ultrasonic treatment, the graphite worms were fragmented into exfoliated graphite nanoplates with diameters of 0.5–25mm and thicknesses of 20–60 nm (see S3 in Supporting Information), as shown by the SEM image in Figure 1b. C O M M U N IC A TI O N www.advmat.de

Journal ArticleDOI
TL;DR: A review of the most recent accomplishments and trends in the field of nanocomposite polymer hydrogels with a focus on creative approaches to generate structures, properties, and function within mostly biotechnological applications is given in this article.
Abstract: The technological need for new and better soft materials as well as the drive for new knowledge and fundamental understanding has led to significant advances in the field of nanocomposite gels. A variety of complex gel structures with unique chemical, physical, and biological properties have been engineered or discovered at the nanoscale. The possibility to form self-assembled and supramolecular morphologies makes organic polymers and inorganic nanoparticles desirable building blocks for the design of water based gels. In this review, we highlight the most recent (2004–2008) accomplishments and trends in the field of nanocomposite polymer hydrogels with a focus on creative approaches to generating structures, properties, and function within mostly biotechnological applications. We examine the impact of published work and conclude with an outline on future directions and challenges that come with the design and engineering of new nanocomposite gels.

Journal ArticleDOI
TL;DR: In this paper, high conducting polyaniline (PANI)-multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by in situ polymerization.

Journal ArticleDOI
TL;DR: In this paper, a general strategy has been demonstrated to achieve optimum electrochemical performance by constructing 3D nanocomposite architecture with the combination of nanosize Sn particles and graphene nanosheets.
Abstract: A general strategy has been demonstrated to achieve optimum electrochemical performance by constructing 3D nanocomposite architecture with the combination of nanosize Sn particles and graphene nanosheets. In the first step, the lithium storage properties of graphene have been investigated by first principles calculations. The results show that lithium can be stably stored on both sides of graphene sheets (LiC3), inducing in a theoretical capacity of 744 mAh/g. In the second step, a synthetic approach has been designed to prepare Sn/graphene nanocomposite with 3D architecture, in which Sn nanoparticles act as a spacer to effectively separate graphene nanosheets. FESEM and TEM analysis revealed the homogeneous distribution of Sn nanoparticles (2–5 nm) in graphene nanosheet matrix. Cyclic voltammetry measurement has proved the highly reversible nature of the reaction between Li+ and Sn/graphene nanocomposite. The 3D nanoarchitecture gives the Sn/graphene nanocomposite electrode an enhanced electrochemical performance. This strategy can be extended to prepare other anode and cathode materials for advanced energy storage and conversion devices such as lithium ion batteries, supercapacitors, and fuel cells.


Journal ArticleDOI
TL;DR: This nanocomposite shows not only a high reversible capacity of approximately 250 mA h g(-1) but also good cycling and rate capability.
Abstract: Double-shelled nanocapsules of V2O5−SnO2 composites were chemically assembled via a one-pot solution method. These hollow nanocapsules are composed of a double-shelled V2O5 matrix that includes a low weight ratio of SnO2 (e.g., 10 or 15%). In these double shells, open-structured V2O5 acts as not only a supporting matrix but also an active electrode component. The gap between the two shells and the hollow cavity provide sufficient space for volume variation during conversion reactions and lithium alloying/dealloying processes. As a promising anode electrode, this nanocomposite shows a large, reversible capacity of 947 mA h g−1 at a rate of 250 mA g−1 and retains a high capacity of 673 mA h g−1 after 50 cycles. Even at a high rate of 2500 mA g−1, the current nanocomposite electrode can still deliver a reversible capacity of 505 mA h g−1. As a cathode electrode, our nanocomposite shows not only a high reversible capacity of ∼250 mA h g−1 but also good cycling and rate capability.

Journal ArticleDOI
Jane Yao1, Xiaoping Shen1, Bei Wang1, Hua-Kun Liu1, Guoxiu Wang1 
TL;DR: In this article, an in situ chemical synthesis approach has been developed to prepare SnO 2 -graphene nanocomposite, which exhibited a reversible lithium storage capacity of 765 ǫ/g in the first cycle and an enhanced cyclability.

Journal ArticleDOI
16 Oct 2009-Small
TL;DR: The silver–graphene nanocomposite film shows a 109-fold increase in electrical conductivity as compared to the graphite oxide film.
Abstract: Nanospacers for graphene: A facile and scalable process for the synthesis of aqueous solutions of isolated silver-decorated graphene sheets (see image) is presented. The silver–graphene nanocomposite film shows a 109-fold increase in electrical conductivity as compared to the graphite oxide film.

Journal ArticleDOI
10 Sep 2009-Polymer
TL;DR: In this article, the surface of ramie cellulose whiskers has been chemically modified by grafting organic acid chlorides presenting different lengths of the aliphatic chain by an esterification reaction.


Journal ArticleDOI
TL;DR: Durability of the nanocomposite film was at least 11 times higher than the Ag/a-TiO(2) film and the main mechanism for silver ion releasing was inter-diffusion of water and silver nanoparticles through pores of the TiO( 2) layer.

Journal ArticleDOI
TL;DR: In this article, the authors compared the performance of FGS-PVDF composites and EG-pVDF nanocomposites and found that FGS remains well dispersed in the composites as evidenced by the lack of the characteristic graphite reflection in composites.
Abstract: PVDF nanocomposites based on functionalized graphene sheets, FGS prepared from graphite oxide, and exfoliated graphite, EG, were prepared by solution processing and compression molding. FGS remains well dispersed in the PVDF composites as evidenced by the lack of the characteristic graphite reflection in the composites. Although the α-phase of PVDF is seen in the EG-based composites, a mixture of α- and β-phases is present in the FGS analogs. SEM and TEM imaging show smooth fractured surfaces with oriented platelets of graphite stacks and obvious debonding from the matrix in the EG-PVDF composites. In contrast, the FGS-PVDF composites show a wrinkled topography of relatively thin graphene sheets bonded well to the matrix. Storage modulus of the composites was increased with FGS and EG concentration. A lower percolation threshold (2 wt %) was obtained for FGS-PVDF composites compared to EG-PVDF composites (above 5 wt %). Lastly, the FGS-PVDF composites show an unusual resistance/temperature behavior. The resistance decreases with temperature, indicating an NTC behavior, whereas EG-PVDF composites show a PTC behavior (e.g., the resistance increases with temperature). We attribute the NTC behavior of the FGS based composites to the higher aspect ratio of FGS which leads to contact resistance predominating over tunneling resistance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 888–897, 2009

Journal ArticleDOI
TL;DR: In this paper, the synthesis of conducting polyaniline-functionalized multi-walled carbon nanotubes (MWCNTs-f-PANI) containing noble metal (Au and Ag) nanoparticles composites was reported.

Journal ArticleDOI
15 Jun 2009-Langmuir
TL;DR: The data presented offer additional support for the hypothesis that zeolite crystals alter polyamide thin film structure when they are present during the interfacial polymerization reaction.
Abstract: Zeolite-polyamide thin film nanocomposite membranes were coated onto polysulfone ultrafiltration membranes by interfacial polymerization of amine and acid chloride monomers in the presence of Linde type A zeolite nanocrystals. A matrix of three different interfacial polymerization chemistries and three different-sized zeolite crystals produced nanocomposite thin films with widely varying structure, morphology, charge, hydrophilicity, and separation performance (evaluated as reverse osmosis membranes). Pure polyamide film properties were tuned by changing polymerization chemistry, but addition of zeolite nanoparticles produced even greater changes in separation performance, surface chemistry, and film morphology. For fixed polymer chemistry, addition of zeolite nanoparticles formed more permeable, negatively charged, and thicker polyamide films. Smaller zeolites produced greater permeability enhancements, but larger zeolites produced more favorable surface properties; hence, nanoparticle size may be considered an additional "degree of freedom" in designing thin film nanocomposite reverse osmosis membranes. The data presented offer additional support for the hypothesis that zeolite crystals alter polyamide thin film structure when they are present during the interfacial polymerization reaction.

Journal ArticleDOI
01 Oct 2009-Carbon
TL;DR: In this article, carbon nanotubes (CNTs) were incorporated in an epoxy matrix that was then reinforced with carbon fibers, and a fixed amount of different types of CNTs (functionalized and non-functionalized) were dispersed in the epoxy matrices, and unidirectional prepregs are produced.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate a new dimension to this 2D nanoscale material by showing the excellent light-triggered acutation of its thermoplastic polyurethane nanocomposites with significantly enhanced mechanical properties.
Abstract: The emerging field of optical-triggered actuators based on polymeric nanocomposite continues to be the focus of considerable research in recent years because of their scientific and technological significance. In principle, dispersing nanofiller with unique characteristics in polymer matrix can not only provide superb enhancement of performance but also afford novel actuation schemes to the systems. Graphene, combining its unusual electrical, thermal, mechanical, and optical properties, can provide the ability to act as “energy transfer” and trigger unit in the realm of nanocomposite actuators. Herein, we demonstrate a new dimension to this 2D nanoscale material by showing the excellent light-triggered acutation of its thermoplastic polyurethane nanocomposites with significantly enhanced mechanical properties. These nanocomposite actuators with 1 wt % loading of sulfonated functionalized graphene sheets (sulfonated-graphene) exhibit repeatable infrared-triggered actuation performance which can strikingly ...

Journal Article
TL;DR: In this paper, the authors compared the performance of FGS-PVDF composites and EG-pVDF nanocomposites and found that FGS remains well dispersed in the composites as evidenced by the lack of the characteristic graphite reflection in composites.
Abstract: PVDF nanocomposites based on functionalized graphene sheets, FGS prepared from graphite oxide, and exfoliated graphite, EG, were prepared by solution processing and compression molding. FGS remains well dispersed in the PVDF composites as evidenced by the lack of the characteristic graphite reflection in the composites. Although the α-phase of PVDF is seen in the EG-based composites, a mixture of α- and β-phases is present in the FGS analogs. SEM and TEM imaging show smooth fractured surfaces with oriented platelets of graphite stacks and obvious debonding from the matrix in the EG-PVDF composites. In contrast, the FGS-PVDF composites show a wrinkled topography of relatively thin graphene sheets bonded well to the matrix. Storage modulus of the composites was increased with FGS and EG concentration. A lower percolation threshold (2 wt %) was obtained for FGS-PVDF composites compared to EG-PVDF composites (above 5 wt %). Lastly, the FGS-PVDF composites show an unusual resistance/temperature behavior. The resistance decreases with temperature, indicating an NTC behavior, whereas EG-PVDF composites show a PTC behavior (e.g., the resistance increases with temperature). We attribute the NTC behavior of the FGS based composites to the higher aspect ratio of FGS which leads to contact resistance predominating over tunneling resistance.

Journal ArticleDOI
TL;DR: In this article, the interfacial shear strength of carbon nanotube (CNT) coated carbon fibers in epoxy was studied using the single-fiber composite fragmentation test.

Journal ArticleDOI
TL;DR: A "nanoparticle-in-alloy" material approach with silicide and germanide fillers leading to a potential 5-fold increase in the thermoelectric figure of merit of SiGe alloys at room temperature and 2.5 times increase at 900 K is presented.
Abstract: We present a "nanoparticle-in-alloy" material approach with silicide and germanide fillers leading to a potential 5-fold increase in the thermoelectric figure of merit of SiGe alloys at room temperature and 2.5 times increase at 900 K. Strong reductions in computed thermal conductivity are obtained for 17 different types of silicide nanoparticles. We predict the existence of an optimal nanoparticle size that minimizes the nanocomposite's thermal conductivity. This thermal conductivity reduction is much stronger and strikingly less sensitive to nanoparticle size for an alloy matrix than for a single crystal one. At the same time, nanoparticles do not negatively affect the electronic conduction properties of the alloy. The proposed material can be monolithically integrated into Si technology, enabling an unprecedented potential for micro refrigeration on a chip. High figure-of-merit at high temperatures (ZT approximately 1.7 at 900 K) opens up new opportunities for thermoelectric power generation and waste heat recovery at large scale.

Journal ArticleDOI
TL;DR: In this paper, the effects of sonication time on the mechanical properties of multiscale composites, which contain reinforcements at varying scales, were studied, and a combination of Halpin-Tsai equations and woven fiber micromechanics was used in hierarchy to predict the structural properties of multi-scale composites.