Vibrational properties of composites based on single-walled carbon nanotubes (SWNTs) and conducting polymers of the type polyaniline (PANI) and poly (3,4-ethylene dioxythiophene) (PEDOT) are reported. For PANI-functionalized SWNTs, the intensity increase of the Raman band at 178 cm-1, associated with radial breathing modes of SWNTs bundles, indicates an additional roping of nanotubes due to the presence of the polymer. The interaction of this composite with NH4OH solution involves an internal redox reaction between PANI and SWNTs. Thus, the polymer chain undergoes a transition from the semi-oxidized state into a reduced one. The functionalization of SWNT side walls with PEDOT is invoked as well.
Carboxylic functionalization (-COOH groups) of carbon nanotubes is known to improve their dispersion properties and increase the electrical conductivity of carbon-nanotube - polymer nanocomposites. We have studied experimentally the effects of this type of functionalization on the thermal conductivity of the nanocomposites. It was found that while even small quantities of carbon nanotubes (~1 wt%) can increase the electrical conductivity, a larger loading fraction (~3 wt%) is required to enhance the thermal conductivity of nanocomposites. Functionalized multi-wall carbon nanotubes performed th…
The weak-chemisorption/charge-transfer picture for adsorption of aromatic molecules over carbon nanotubes, proposed in the commented paper, is criticized.
The influence of carbon multi-walled nanotubes (MWCNTs) and halloysite nanotubes (HNTs) on the physical, thermal, mechanical, and electrical properties of EVA (ethylene vinyl acetate) copolymer was investigated. EVA-based nanocomposites containing MWCNTs or HNTs, as well as hybrid nanocomposites containing both nanofillers were prepared by melt blending. Scanning electron microcopy (SEM) images revealed the presence of good dispersion of both kinds of nanotubes throughout the EVA matrix. The incorporation of nanotubes into the EVA copolymer matrix did not significantly affect the crystallizati…
A spectroscopic study of the amino functionalization of double-walled carbon nanotube (DWCNT) is performed. Original experimental investigations by near edge X-ray absorption fine structure spectroscopy at the C and O K-edges allow one to follow the efficiency of the chemistry during the different steps of covalent functionalization. Combined with Raman spectroscopy, the characterization gives a direct evidence of the grafting of amino-terminated molecules on the structural defects of the DWCNT external wall, whereas the internal wall does not undergo any change. Structural and mechanical inve…
An electrospun membrane for vascular stent coating made of 2-methacryloyloxyethyl phosphorylcholine and butyl methacrylate copolymer (MPC-co-BMA), also known as (PMB), reinforced with functionalized and nitrogen doped reduced graphene oxide (f-NrGO) is presented. This membrane due to the nitrogen doped reduced graphene oxide (NrGO) negative electric charge has the capacity to repeal low density lipoproteins (LDL), which under specific conditions are the main cause of atherosclerotic disease. The NrGO functionalization process is detailed, as it creates strong bonds between NrGO and PMB, avoidi…
For single-walled carbon nanotube (SWNT) field effect transistors, vertical scaling of high k dielectrics by atomic layer deposition (ALD) currently stands at ~8nm with subthreshold swing S~70-90 mV/decade at room temperature. ALD on as-grown pristine SWNTs is incapable of producing a uniform and conformal dielectric layer due to the lack of functional groups on nanotubes and that nucleation of an oxide dielectric layer in the ALD process hinges upon covalent chemisorption on reactive groups on surfaces. Here, we show that by non-covalent functionalization of SWNTs with ploy-T DNA molecules (d…
The results of a study on the evolution of HiPco single-walled carbon nanotubes during the oxidizing action of H2SO4 and HNO3 are presented. The process conditions used have been chosen so as to avoid any significant damage to the nanotube structure. The type and level of functionalization, the location of the grafted functions on the surface of the nanotube and the changes in morphological characteristics of the samples were examined by using a wide and complementary range of analytical techniques. We propose an explanation for the differences in the oxidizing action of sulfuric and nitric ac…
We present a near IR photoresponse study of large area multi-walled carbon nanotube/poly(3-hexylthiophene)-block-polystyrene polymer (MWNT/P3HT-b-PS) nanocomposite films for different loading ratio of MWNT into the polymer matrix. We show that the photocurrent strongly depends on the position of the laser spot with maxiumum photocurrent occurring at the metal - film interface. In addition, compared to the pure MWNT film, the photoresponse is much larger in the MWNT/polymer composite films. The time constant for the photoresponse is slow and varies between 0.6 and 1.2 seconds. We explain the ph…
We identify a class of covalent functionalizations that preserves or controls the conductance of single-walled metallic carbon nanotubes. [2+1] cycloadditions can induce bond cleaving between adjacent sidewall carbons, recovering in the process the $sp^2$ hybridization and the ideal conductance of the pristine tubes. This is radically at variance with the damage permanently induced by other common ligands, where a single covalent bond is formed with a sidewall carbon. Chirality, curvature, and chemistry determine bond cleaving, and in turn the electrical transport properties of a functionalize…
Boron nitride nanotubes (BNNTs) are of intense scientific interests due to their unique physiochemical properties and prospective applications in various nanotechnologies. A critical problem hampering the application processing of BNNTs is the outer sidewall functionalization, which is primarily acquired to lead BNNTs dispersible in various solvents. Furthermore, the surface of BNNTs should be intelligently designed and precisely controlled to satisfy the specific demands of different applications. For these purposes, covalent and noncovalent approaches have been factually developed for openin…
The assembly of aligned carbon nanotubes (CNT) into fibers (CNTF) is a convenient approach to exploit and apply the unique physico-chemical properties of CNTs in many fields. CNT functionalization has been extensively used for their implementation into composites and devices. However, CNTF functionalization is still in its infancy, due to the challenges associated with preservation of CNTF morphology. Here, we report a thorough study of the gas-phase functionalization of CNTF fabrics using ozone that was generated in situ from a UV-source. By contrast with liquid-based oxidation methods, this …
To achieve high thermal conductivity (k) of polymer graphene nanocomposites, it is critically important to achieve efficient thermal coupling between graphene and its surrounding polymers through effective functionalization schemes. In this work, we demonstrate that edge-functionalization of graphene nanoplatelets (GnPs) can enable a larger enhancement of effective thermal conductivity in polymer-graphene nanocomposites, relative to basal plane functionalization. Effective thermal conductivity for edge case is predicted, through molecular dynamics simulations, to be up to 48% higher relative t…
We have combined large-scale, $Γ$-point electronic-structure calculations with the maximally-localized Wannier functions approach to calculate efficiently the band structure and the quantum conductance of complex systems containing thousands of atoms while maintaining full first-principles accuracy. We have applied this approach to study covalent functionalizations in metallic single-walled carbon nanotubes. We find that the band structure around the Fermi energy is much less dependent on the chemical nature of the ligands than on the $sp^3$ functionalization pattern disrupting the conjugation…
Bulk samples of carbon multilayer nanotubes with the structure of nested cones (fishbone structure) suitable for transport measurements, were prepared by compressing under high pressure (~25 kbar) a nanotube precursor synthesized through thermal decomposition of polyethylene catalyzed by nickel. The structure of the initial nanotube material was studied using high-resolution transmission electron microscopy. In the low-temperature range (4.2 - 100 K) the electric resistance of the samples changes according to the law ln ρ~ (T_0/T)^{1/3}, where T_0 ~ 7 K. The measured magnetoresistance is quadr…
We report the functionalization of carbon nanotubes with two azobenzene-based chromophores with large internal dipole moments and opposite dipole orientations. The molecules are attached to the nanotubes non-covalently via a pyrene tether. A combination of characterization techniques shows uniform molecular coverage on the nanotubes, with minimal aggregation of excess chromophores on the substrate. The large on/off ratios and the sub-threshold swings of the nanotube-based field-effect transistors (FETs) are preserved after functionalization, and different shifts in threshold voltage are observ…
The stability, electronic and optical properties of single-walled carbon nanotubes (CNTs) and graphene noncovalently functionalized with free-base tetraphenylporphyrin (TPP) molecules is addressed by density functional theory calculations, including corrections to dispersive interactions. We study the TPP physisorption on 42 CNT species, particularly those with chiral indices ($n$,$m$), where $5 \leq n \leq 12$ and $0\leq m\leq n$. Our results show a quite strong $π$-$π$ interaction between TPP and the CNT surface, with binding energies ranging from 1.1 to 1.8 eV, where higher energies can be …
Polydimethylsiloxane (PDMS) is an insulator and it is commonly used in fabrication of micro-structures but there is a need of electrical conductive PDMS. Therefore, this research is mainly focused on producing PDMS nanocomposites with high electrical conductivity. Thus, we produced highly conductive PDMS nanocomposites which were filled with multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs). Due to the synergistic effect between CNTs and GNPs inside a polymeric matrix, we expected to obtain more conductive nanocomposites than PDMS nanocomposite filled with only CNTs. Addi…
Biomedical applications of carbon nanotubes have attracted much attention in recent years. Here, we summarize our previously developed protocols for functionalization and bioconjugation of single wall carbon nanotubes (SWNTs) for various biomedical applications including biological imaging, sensing and drug delivery. Sonication of SWNTs in solutions of phospholipid-polyethylene glycol (PL-PEG) is our most commonly used protocol of SWNT functionalization. Compared to other frequently used covalent strategies, our non-covalent functionalization protocol largely retains the intrinsic optical prop…
The electrical conductivity of the polyimide R-BAPB polymer filled with single-wall carbon nanotubes (CNT) with chirality (5,5) is modeled using a multi-scale approach. The modeling starts with molecular dynamics simulations of time-dependent fluctuating atomic configurations of polymer filled CNTs junctions. Then the atomic positions obtained in the first step are used to perform fully first-principles microscopic calculations of the CNTs junctions contact resistances using the Green's function based quantum transport technique. And finally, those contact resistances are supplied as an input …
Materials comprising carbon nanotube (CNT) aligned nanowire (NW) polymer nanocomposites (A-PNCs) are emerging as next-generation materials for use in aerospace structures. Enhanced operating regimes, such as operating temperatures, motivate the study of CNT aligned NW ceramic matrix nanocomposites (A-CMNCs). Here we report the synthesis of CNT A-CMNCs through the pyrolysis of CNT A-PNC precursors, thereby creating carbon matrix CNT A-CMNCs. Characterization reveals that the fabrication of high strength, high temperature, lightweight next-generation aerospace materials is possible using this me…
Micromechanical modeling and mechanical properties of polyurethane (PU) hybrid nanocomposite foams with multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) were investigated by mean of tensile strength, hardness, impact strength and modified Halpin-Tsai equation. Three types of graphene, with varied flake sizes and specific surface areas (SSA), were utilized to study the effect of graphene types on the synergistic effect of MWCNT/GNP hybrid nanofillers. The results indicate a remarkable synergetic effect between MWCNTs and GNP-1.5 (1:1) with a flake size of 1.5 μm and a hi…
Since solid-state heat transport in a highly porous nanocomposite strongly depends on the thermal boundary conductance (TBC) between constituent nanomaterials, further suppression of the TBC is important for improving performance of thermal insulators. Here, targeting a nanocomposite fabricated by stamping fumed silica nanoparticles, we perform a wide variety of surface functionalization on fumed silica nanoparticles by silane coupling method and investigate the impact on the thermal conductivity (Km). The Km of the silica nanocomposite is approximately 20 and 9 mW/m/K under atmospheric and va…
Hollow carbon spheres (HCS) covered with metal oxide nanoparticles (SnO2 and MnO2, respectively) were successfully synthesized and investigated regarding their potential as anode materials for lithium-ion batteries. Raman spectroscopy shows a high degree of graphitization for the HCS host structure. The mesoporous nature of the nanocomposites is confirmed by Brunauer-Emmett-Teller analysis. For both metal oxides under study, the metal oxide functionalization of HCS yields a significant increase of electrochemical performance. The charge capacity of HCS/SnO2 is 370 mAh/g after 45 cycles (266 mA…
In this work, a novel electrospun conductive polymer nanocomposite made of polycaprolactone with an exohedral complex made of multiwalled carbon nanotubes and fullerene C60 was prepared and characterized. The preparation was straightforward and the complexes self-assembled within the nanocomposite fibers. The nanocomposite showed electrical switching behavior due to charge accumulation of fullerene C60 upon electrical stimulation. Write-once read-many memory devices were fabricated by electrospinning a nanocomposite with 0.8%wt. fullerene C60 onto interdigitated coplanar electrodes. The device…
Nanomaterials hold much promise for biological applications, but they require appropriate functionalization to provide biocompatibility in biological environments. For non-covalent functionalization with biocompatible polymers, the polymer must also remain attached to the nanomaterial after removal of its excess to mimic the high dilution conditions of administration in vivo. Reported here are the synthesis and utilization singly-substituted conjugates of dextran and a phospholipid (Dextran-DSPE) as stable coatings for nanomaterials. Suspensions of single walled carbon nanotubes were found not…
The hollow inside of single-wall carbon nanotubes (SWCNT) provides a unique degree of freedom to investigate chemical reactions inside this confined environment and to study the tube properties. It is reviewed herein, how encapsulating fullerenes, magnetic fullerenes, $^{13}$C isotope enriched fullerenes and organic solvents inside SWCNTs enables to yield unprecedented insight into their electronic, optical, and interfacial properties and to study their growth. Encapsulated C$_{60}$ fullerenes are transformed to inner tubes by a high temperature annealing. The unique, low defect concentration …
We have fabricated field effect transistors from carbon nanotubes using a novel selective placement scheme. We use carbon nanotubes that are covalently bound to molecules containing hydroxamic acid functionality. The functionalized nanotubes bind strongly to basic metal oxide surfaces, but not to silicon dioxide. Upon annealing, the functionalization is removed, restoring the electronic properties of the nanotubes. The devices we have fabricated show excellent electrical characteristics.
We present results of extensive theoretical studies concerning stability, morphology, and band structure of single wall carbon nanotubes (CNTs) covalently functionalized by -CHn(for n=2,3,4),-NHn(for n=1,2,3,4),-COOH and -OH groups. Our studies are based on ab initio calculations in the framework of the density functional theory. We determine the dependence of the binding energies on the concentration of the adsorbed molecules, critical densities of adsorbed molecules, global and local changes in the morphology, and electronic structure paying particular attention to the functionalization indu…
Nanocomposites based on graphene and carbon nanotubes dispersed in polypyrrole or poly(3,4ethylenedioxy)thiophene have been prepared and their performance as cold cathodes for field emission has been evaluated. It was found that the polymer matrix will degrade during the field emission process and result in unstable performance. Electropolymerization of the composites results in significantly better field emission performance, but the stability is still a major problem. Deposition of composites onto a stable membrane was proposed as a strategy for improving the performance of electrodes. The f…
Electronic and optoelectronic devices based on thin films of carbon nanotubes are currently limited by the presence of metallic nanotubes. Here we present a novel approach based on nanotube alkyl functionalization to physically remove the metallic nanotubes from such network devices. The process relies on preferential thermal desorption of the alkyls from the semiconducting nanotubes and the subsequent dissolution and selective removal of the metallic nanotubes in chloroform. The approach is versatile and is applied to devices post-fabrication.
We use ab initio density functional calculations to study the chemical functionalization of single-wall carbon nanotubes and graphene monolayers by silyl (SiH3) radicals and hydrogen. We find that silyl radicals form strong covalent bonds with graphene and nanotube walls, causing local structural relaxations that enhance the sp3 character of these graphitic nanostructures. Silylation transforms all carbon nanotubes into semiconductors, independent of their chirality. Calculated vibrational spectra suggest that specific frequency shifts can be used as a signature of successful silylation.
The functionalization of single-walled carbon nanotubes (SWCNTs) with luminescent sp$^{3}$ defects has greatly improved their performance in applications such as quantum light sources and bioimaging. Here, we report the covalent functionalization of purified semiconducting SWCNTs with stable organic radicals (perchlorotriphenylmethyl, PTM) carrying a net spin. This model system allows us to use the near-infrared photoluminescence arising from the defect-localized exciton as a highly sensitive probe for the short-range interaction between the PTM radical and the SWCNT. Our results point toward …
pH-Responsive Glyphosate Adsorption on Hydroxylated Carbon Nanotubes: From Electronic Structure to Molecular Dynamics
Universidade Federal de Alfenas - UNIFAL-MG（阿尔芬纳斯联邦大学）；Instituto de Ciências Exatas - ICEx（理学院）；Laboratório de Modelagem Computacional - La Model（计算建模实验室）；Institute of Science and Tecnology - ICT（科学技术研究所）
The work presents a comprehensive methodology to determine the Shielding Effectiveness (SE) of single-walled carbon nanotubes (SWCNTs)/polymer nanocomposites. Here, an algorithm based on Ant Colony Optimization (ACO) was employed to determine the electrical conductivity (σ) of these nanocomposites as a function of SWCNT concentration. Then, these σ values were used to compute the SE values as a function of frequency and concentration. Specifically, a pseudo three-dimensional (3D) percolation model was developed to study the effects of random connectivity of SWCNTs to one another on the σ value…
The controlled functionalization of single-walled carbon nanotubes with luminescent sp3-defects has created the potential to employ them as quantum-light sources in the near-infrared. For that, it is crucial to control their spectral diversity. The emission wavelength is determined by the binding configuration of the defects rather than the molecular structure of the attached groups. However, current functionalization methods produce a variety of binding configurations and thus emission wavelengths. We introduce a simple reaction protocol for the creation of only one type of luminescent defect…
Carbon nanotubes exhibit many unique intrinsic physical and chemical properties and have been intensively explored for biological and biomedical applications. In this review, we summarize the main results of our and other groups in this field and clarify that surface functionalization is critical to the behaviors of carbon nanotubes in biological systems. Ultra-sensitive detection of biological species with carbon nanotubes can be realized after surface passivation to inhibit the non-specific binding of bio-molecules on the hydrophobic nanotube surface. Electrical nanosensors based on nanotube…
Gold nanospheres, single wall carbon nanotubes (SWNT), and diamonoids were phyically incorporated into the negative photoresist SU-8. the mixtures were spin cast onto silicon or aluminium coated silicon wafers. ASTM standard D638 tensile specimens were lithographically patterned in the materials and then released from the substrate using Microchem'Omnicoat or an anodic metal dissolution process. the residual stresses, elastic moduli, and viscosity of the SU-8. Resistivity measurements of SU-8/SWNT nanocomposites were also investigates. We found the effective modulus and viscosity of the SU-8 t…
Nanomaterials have been actively pursued for biological and medical applications in recent years. Here, we report the synthesis of several new poly(ethylene glycol) grafted branched-polymers for functionalization of various nanomaterials including carbon nanotubes, gold nanoparticles (NP) and gold nanorods (NRs), affording high aqueous solubility and stability for these materials. We synthesize different surfactant polymers based upon poly-(g-glutamic acid) (gPGA) and poly(maleic anhydride-alt-1-octadecene) (PMHC18). We use the abundant free carboxylic acid groups of gPGA for attaching lipophi…
The promise of enhanced performance has motivated the study of one dimensional nanomaterials, especially aligned carbon nanotubes (A-CNTs), for the reinforcement of polymeric materials. While early work has shown that CNTs have remarkable theoretical properties, more recent work on aligned CNT polymer matrix nanocomposites (A-PNCs) have reported mechanical properties that are orders of magnitude lower than those predicted by rule of mixtures. This large difference primarily originates from the morphology of the CNTs that reinforce the A-PNCs, which have significant local curvature commonly ref…
High performance nanocomposites require well dispersion and high alignment of the nanometer-sized components, at a high mass or volume fraction as well. However, the road towards such composite structure is severely hindered due to the easy aggregation of these nanometer-sized components. Here we demonstrate a big step to approach the ideal composite structure for carbon nanotube (CNT) where all the CNTs were highly packed, aligned, and unaggregated, with the impregnated polymers acting as interfacial adhesions and mortars to build up the composite structure. The strategy was based on a bio-in…
We report on a model of polymer nanocomposites with fibrous fillers which explicitly considers the microscopic filler features and replicates the composites as random distributions of particles interconnected via electron tunneling. By exploiting the critical path method, we are able to obtain simple formulas, applicable to most nanotube and nanofiber composites, which allow to infer the overall composite conductivity starting from few parameters like filler volume fraction, size, and aspect-ratio. The validity of our formulation is assessed by reinterpreting existing experimental results and …
The paper aims at the development of a digital twin modelling the electrical conductivity of multi-wall carbon nanotube (MWCNT)/polymer nanocomposite. A comparative analysis is conducted for various formulations of boundary conditions in the representative volume element (RVE) with uniform and isotropic distribution of CNTs. Three types of boundary conditions studied: uniform boundary potentials for an RVE, uniform boundary potentials for a chain of two RVEs, and periodic boundary potentials. It is demonstrated that to calculate the electrical conductivity of the material correctly, the implem…
An extensive first-principles study of fully exo-hydrogenated zigzag (n,0) and armchair (n,n) single wall carbon nanotubes (C$_n$H$_n$), polyhedral molecules including cubane, dodecahedrane, and C$_{60}$H$_{60}$ points to crucial differences in the electronic and atomic structures relevant to hydrogen storage and device applications. C$_n$H$_n$'s are estimated to be stable up to the radius of a (8,8) nanotube, with binding energies proportional to 1/R. Attaching a single hydrogen to any nanotube is always exothermic. Hydrogenation of zigzag nanotubes is found to be more likely than armchair na…
We present a general approach to the computational design of nanostructured chemical sensors. The scheme is based on identification and calculation of microscopic descriptors (design parameters) which are used as input to a thermodynamic model to obtain the relevant macroscopic properties. In particular, we consider the functionalization of a (6,6) metallic armchair single-walled carbon nanotube (SWNT) by nine different 3d transition metal (TM) atoms occupying three types of vacancies. For six gas molecules (N_{2}, O_{2}, H_{2}O, CO, NH_{3}, H_{2}S) we calculate the binding energy and change i…
In recent years, the immiscible polymer blend system has attracted much attention as the matrix of nanocomposites. Herein, from the perspective of dynamics, the control of the carbon nanotubes (CNTs) migration aided with the interface of polystyrene (PS) and poly(methyl methacrylate) (PMMA) blends was achieved through a facile melt mixing method. Thus, we revealed a comprehensive relationship between several typical CNTs migrating scenarios and the microwave dielectric properties of their nanocomposites. Based on the unique morphologies and phase domain structures of the immiscible matrix, we …
DFT calculation of various atomic species on graphene sheet is investigated as prototypes for formation of nano-structures on carbon nanotube (CNT) wall. We investigate computationally adsorption energies and adsorption sites on graphene sheet for a lot of atomic species including transition metals, noble metals, nitrogen and oxygen, using the DFT calculation as a prototype for CNT. The suitable atomic species can be chosen as each application from those results. The calculated results show us that Mo and Ru are bounded strongly on graphene sheet with large diffusion barrier energy. On the oth…
The controlled covalent functionalization of semiconducting single-walled carbon nanotubes (SWCNTs) with luminescent sp$^{3}$ defects leads to additional narrow and tunable photoluminescence features in the near-infrared and even enables single-photon emission at room temperature, thus strongly expanding their application potential. However, the successful integration of sp$^{3}$-functionalized SWCNTs in optoelectronic devices with efficient defect state electroluminescence not only requires control over their emission properties but also a detailed understanding of the impact of functionaliza…
Carbon nanotubes (CTNs) with large aspect-ratios are extensively used to establish electrical connectedness in polymer melts at very low CNT loadings. However, the CNT size polydispersity and the quality of the dispersion are still not fully understood factors that can substantially alter the desired characteristics of CNT nanocomposites. Here we demonstrate that the electrical conductivity of polydisperse CNT-epoxy composites with purposely-tailored distributions of the nanotube length L is a quasiuniversal function of the first moment of L. This finding challenges the current understanding t…
Nanoparticles can influence the properties of polymer materials by a variety of mechanisms. With fullerene, carbon nanotube, and clay or graphene sheet nanocomposites in mind, we investigate how particle shape influences the melt shear viscosity $η$ and the tensile strength $τ$, which we determine via molecular dynamics simulations. Our simulations of compact (icosahedral), tube or rod-like, and sheet-like model nanoparticles indicate an order of magnitude increase in the viscosity $η$ relative to the pure melt. This finding evidently can not be explained by continuum hydrodynamics and we prov…
We investigate the nitrogen substitutional impurity in semiconducting zigzag and metallic armchair single-wall carbon nanotubes using ab initio density functional theory. At low concentrations (less than 1 atomic %), the defect state in a semiconducting tube becomes spatially localized and develops a flat energy level in the band gap. Such a localized state makes the impurity site chemically and electronically active. We find that if two neighboring tubes have their impurities facing one another, an intertube covalent bond forms. This finding opens an intriguing possibility for tunnel junction…
Different types of graphene-related materials (GRM) are industrially available and have been exploited for thermal conductivity enhancement in polymers. These include materials with very different features, in terms of thickness, lateral size and composition, especially concerning the oxygen to carbon ratio and the possible presence of surface functionalization. Due to the variability of GRM properties, the differences in polymer nanocomposites preparation methods and the microstructures obtained, a large scatter of thermal conductivity performance is found in literature. However, detailed cor…
The covalent functionalization of carbon allotropes represents a main topic in the growing field of nano materials. However, the development of functional architectures is impeded by the intrinsic polydispersibility of the respective starting material, the unequivocal characterization of the introduced functional moieties and the exact determination of the degree of functionalization. Based on a novel carbon allotrope functionalization reaction, utilizing λ^3-iodanes as radical precursor systems, we were able to demonstrate the feasibility to separate and to quantify thermally detached functio…
Interfaces remain one of the major issues in limiting the understanding and designing polymer nanocomposites due to their complexity and pivotal role in determining the ultimate composites properties. In this study, we take multi-walled carbon nanotubes/silicone rubber nanocomposites as a representative example, and have for the first time studied the correlation between high-frequency dielectric dispersion and static/dynamic interfacial characteristics. We have found that the interface together with other meso-structural parameters (volume fraction, dispersion, agglomeration) play decisive ro…
PMMA and Poly carbonate (PC) are wonderful low cost materials which can be easily tailored and shaped. However they have poor mechanical, thermal and electrical properties which are required to be enhanced in several applications where along with high strength, a quick heat transfer becomes a necessity. Carbon nanotubes (CNT) are excellent new materials having extraordinary mechanical and transport properties. In this paper we report results of fabricating composites of varying concentrations of CNTs with PMMA and PC and measurements of thermal conductivity data by a simple transient heat flow…
