Molecular dynamics study of nano mass transfer in a vibrating cantilevered carbon-nanotube

We investigate the nano mass transfer in an ultrahigh frequency carbon-nanotube-resonator encapsulating a nanocluster via classical molecular dynamics simulations. When the carbon-nanotube-resonator vibrated, the encapsulated copper nanocluster more rapidly approached the end of the cantilevered carbon-nanotube-resonator. Such phenomena were due to the migration of the encapsulated copper nanocluster due to the centrifugal force induced by the vibrating nanotube resonator. So the resonance frequency change could be time-dependently found. For the movable copper nanocluster in carbon nanotube resonator, the vibrational spectra when the copper nanocluster inside the carbon nanotube resonator rapidly settled at the capped edge were different from those obtained when the copper nanocluster continuously oscillated inside the carbon nanotube resonator. Such results showed that the frequency of the carbon-nanotube-resonator encapsulating the movable copper nanocluster could be adjusted by controlling the mean position of the oscillating copper nanocluster. The movable nanocluster inside a carbon-nanotube can be applied to a nanotube-based data storage media by sensing the position of the nanocluster.     

Molecular dynamics modeling and simulations of a single-walled carbon-nanotube-resonator encapsulating a finite nanoparticle

In this paper, we investigate a cantilevered (3,3) carbon-nanotube-resonator encapsulating finite-length nanoparticle via classical molecular dynamics simulations. We address a modeling technique to perform the effective molecular dynamics simulations to simply obtain the fundamental frequency shifts of the cantilevered single-walled carbon-nanotube-resonator encapsulating a finite nanoparticle. The possible frequency-shift-ranges could be changed with controlling the mass and the position of the encapsulated nanoparticle, and reached 18–55% of the fundamental resonance frequency of bare CNT-resonator. We found an important calibrating single parameter to estimate the possible frequency-shift-ranges, which could be regressed by a quadratic function.     

Hierarchical Fullerene Assembly: Seeded Coprecipitation and Electric Field Directed Assembly

Hierarchical C₆₀ colloidal films are assembled from nanoscale to macroscale. Fullerene molecular crystals are grown via seeded cosolvent precipitation with mixed solvent [tetrahydronaphthalene (THN)/trimethylpyridine (TMP)] and antisolvent 2‐propanol. The fullerene solutions are aged under illumination, which due to the presence of TMP reduces the free monomer concentration through fullerene aggregation into nanoparticles. The nanoparticles seed the growth of monodisperse fullerene colloids on injection into the antisolvent. Diverse colloidal morphologies are prepared as a function of injection volume and fullerene solution concentration. The high fullerene solubility of THN enables C₆₀ colloids to be prepared in quantities sufficient for assembly (5 × 10⁸). Electric fields are applied to colloidal C₆₀ platelets confined to two dimensions. The particles assemble under dipolar forces, dielectrophoretic forces, and electrohydrodynamic flows. Frequency‐dependent phase transitions occur at the critical Maxwell–Wagner crossover frequency, where the effective polarizability of the particles in the medium is substantially reduced. Structures form as a function of field strength, frequency, and confinement including hexagonal, oblique, string fluid, coexistent hexagonal‐rhombic, and tetratic.     

Molecular dynamics investigations on the interfacial energy and adhesive strength between C60-filled carbon nanotubes and metallic surface

The mechanical and adhesive properties of C₆₀@(10,10) carbon nanopeapods (CNPs) adhering to gold surfaces are investigated by atomistic simulations. The effects of C₆₀ fill density, tube length, surrounding temperature, and peeling velocity on the adhesion behavior are studied. Results show that the interfacial binding energy of CNPs (which depends on the C₆₀ fill density and temperature) is 2.0∼4.4% higher than that of (10,10) single-walled CNTs and 3.4∼4.7% lower than that of (5,5)@(10,10) double-walled CNTs (DWCNTs). Despite their lower interfacial binding energy, CNPs have a higher adhesive strength than that of DWCNTs (1.53 nN vs. 1.4 nN). Distinct from the inner tubes of DWCNTs, which have continuum mechanical properties, the discrete C₆₀ molecules that fill CNPs exhibit unique composite mechanical properties, with high flexibility and bend-buckling resistance. The bend-buckling forces for CNPs filled with a low/medium fill density of C₆₀ are approximately constant. When the fill density is 1 C₆₀ molecule per nanometer length, the bend-buckling force dramatically increases.     

[60]Fullerene as a Novel Photoinduced Antibiotic

Abstract

The antibacterial activity of [60]fullerene (C₆₀), dissolved with poly(vinylpyrrolidone) K30 (PVP), was studied. Under photo‐irradiation, C₆₀/PVP aqueous solutions showed antibacterial activity, whereas PVP solution alone or fullerene solutions in the absence of light showed no activity. These results reveal that C₆₀ is a potentially good device as a photoinduced antibacterial agent.     

Design and analysis of sandwiched fullerene-graphene composites using molecular dynamics simulations

Computational design of a novel carbon based hybrid material that is composed of fullerene units covalently sandwiched between parallel graphene sheets is presented. In this regard, atomistic models for the proposed novel material structure are generated via a systematic approach by employing different fullerene types (i.e. C₁₈₀, C₃₂₀, C₅₄₀ and C₇₂₀) as sandwich cores. Then, thermodynamic stability of the atomistic structures is checked by monitoring free energy profiles and junctional bond configurations which are obtained through classical molecular dynamics (MD) simulations. Thermodynamic feasibility of all atomistic specimens with different fullerene types is suggested by the energy profiles, because total configuration energies for all systems are minimized and remained stable over a long period of time. Furthermore, mechanical behavior of the nano-sandwiched material system is investigated by performing compression tests via MD simulations and basic deformation mechanisms underlying the compressive response are determined. By detailed examination, it is shown that proposed nano-sandwiched material can be identified as quasi-foam material due to comparable energy absorbing characteristics. Furthermore, regarding the effect of fullerene size on the compressive response, it is found that for a given stress level, specimens with larger fullerenes exhibit higher energy absorbing capacity.     

Catalytic activity of hybrid platinum nanoparticle-[C60]fullerene nanowhisker composites for 4-nitrophenol reduction

Abstract

Composites comprising platinum nanoparticles loaded on [C₆₀]fullerene nanowhiskers were prepared by a liquid-liquid interfacial precipitation method. The synthesized platinum nanoparticle-[C₆₀]fullerene nanowhisker composites were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. The catalytic activity of the platinum nanoparticle-[C₆₀]fullerene nanowhisker composites was confirmed for the reduction of 4-nitrophenol by UV–vis spectroscopy. The reduction of 4-nitrophenol catalyzed by the platinum nanoparticle-[C₆₀]fullerene nanowhisker composites followed the pseudo-first-order reaction rate law.     

Intercalation of C<Subscript>60</Subscript> fullerene crystals with calcium and barium via self-propagating high-temperature synthesis

We report a process for rapid intercalation of C₆₀ fullerene crystals using self-propagating high-temperature synthesis. The process has been used to intercalate C₆₀ fullerene crystals with calcium and barium. The superconducting transition temperatures of the intercalated fullerites have been measured, and the calcium-intercalated C₆₀ fullerene crystals have been characterized by X-ray diffraction.     

Kinetics of Fullerene Formation in a Contact Arc Generator

Abstract

A kinetic model of the fullerene growth process in a contact arc generator is developed. On the basis of the kinetic model, the yield of the magic fullerenes C₆₀ and C₇₀ is calculated. The fullerene yield is determined by the temperature gradient in the fullerene formation zone, the carbon vapor concentration and the helium jet velocity in the interelectrode space. We found that the upper boundary value of the magic fullerene yield was about 20%.     

Extraction equilibria in a fullerene-containing C<Subscript>60</Subscript>-C<Subscript>70</Subscript>-<Emphasis Type="Italic">o</Emphasis>-Xylene-<Emphasis Type="Italic">i</Emphasis>-butylamine-water system

Extraction equilibria of the liquid(I)-liquid(II) type have been studied for the first time in a system containing light fullerenes C₆₀ and C₇₀. The experiments were performed with a five-component mixture of fullerene C₆₀, fullerene C₇₀, o-xylene, ibutylamine, and water at 25°C. Isothermal diagrams describing the distribution of fullerene components between separating liquid phases have been obtained. The distribution coefficients of fullerenes (C₆₀ and C₇₀ concentrations in the xylene phase relative to those in the amine phase) are found to be almost constant and approximately equal to ～16.1 for both C₆₀ and C₇₀.     

A STUDY ON THE THERMAL STABILITY TO 1000°C OF VARIOUS CARBON ALLOTROPES AND CARBONACEOUS MATTER BOTH UNDER NITROGEN AND IN AIR

ABSTRACT

The thermal behavior of graphite, C₆₀ fullerene, fullerene black (carbon soot containing fullerenes), extracted fullerene black and diamond has been analyzed to 1000°C by TGA–DTA (thermogravimetric analysis and differential thermal analysis) under a nitrogen flow at a heating rate of 20°C/min. Very small weight losses have been recorded in the case of graphite and diamond. Furthermore no diamond graphitization has been observed. The sublimation of pure C₆₀ and the fullerene fraction of fullerene black (both pristine and extracted) has been observed and discussed.

The combustion reaction in air flow of graphite, C₆₀ and C₇₀ fullerenes, fullerene black (both unextracted and extracted), carbon nanotubes and diamond has been studied by TGA–DTA at a heating rate of 20°C/min. C₇₀ fullerene and fullerene black have been found to be the most reactive carbon materials with O₂. The role played by C₇₀ in the degradation of fullerites has been discussed. Among the carbon materials examined, the best resistance to O₂ attack has been shown by diamond and carbon nanotubes. The behavior of graphite is intermediate between diamond and fullerene blacks. The behavior of C₆₀ fullerene appears closer to that of graphite although it appears to be more reactive with O₂. Samples of graphite and carbon blacks N375 and N234 have been studied by TGA–DTA in air flow before and after a radiation treatment with neutrons or γ radiation. The effect of the radiation damage in the combustion reaction of these carbon materials has been discussed.     

Search for C60 Fullerene in Char Produced on a Norway Spruce by Lightning

Abstract

A search was made for C₆₀ fullerene by High Performance Liquid Chromatography in char formed on a Norway Spruce struck by lightning. Firm proof that C₆₀ occurs in the char was not obtained. However, the evidence showed the possible presence of 1 ppb C₆₀.     

Fullerene Research in Poland

Abstract

Main results of the investigations of fullerene and its derivatives are briefly reviewed. Such topics as plasma spectroscopy, fullerenes and nanotubes formation, C₆₀ carbyne knots, fullerene reduction and doping, charge transfer states and electroabsorption of C₆₀, electrical conductivity, superconductivity, ESR properties, fullerene clathrates, C₆₀/C₇₀ complexes with organic donors, fullerene adducts, hydrogenated fullerenes, metallofullerenes and carbon nanotubes are discussed.     

Fullerene C<Subscript>60</Subscript> diffusion in thin layers of amorphous polymers: Polystyrene and poly(α-methylstyrene)

The outdiffusion of fullerene C₆₀ from submicron films of polymer-fullerene blends has been studied by thermodesorption mass spectrometry (TDMS). The energy parameters of C₆₀ diffusion in polystyrene and poly(α-methylstyrene) were determined and compared to the parameters of desorption of C₆₀ molecules from a multilayer film of pure fullerene deposited onto a substrate from toluene solution.     

On Some Complexes of Allyl Derivatives of C60 Fullerene: Simulation of Molecular and Electron Structure by DFT

Abstract

The problem of existence of η³–π‐complexes of transition metal atoms with the allyl type derivatives C₆₀X₃ of C₆₀ fullerene is discussed. It is shown that complexes C₆₀X₃Co(CO)₃ (X = H, F, Cl, Br), C₆₀H₃NiC₅H₅, C₆₀H₃Fe(CO)C₅H₅, where three atoms X are bound to the C atoms of fullerene in the α‐positions relative to the same five‐membered ring in the C₆₀ fullerene, must be sufficiently stable. In these complexes the metal atoms are η³–π‐bound to the fullerene cage. In contrast to this, the metal atoms with the same allyl type C₆₀H₃ derivative of C₆₀ fullerene in the C₆₀H₃Li and C₆₀H₃FeC₅H₅ complexes are η⁵–π‐coordinated to the carbon cage. Calculations were carried out by the DFT with the exchange‐correlation potential by Perdew–Burke–Ernzerhow.     

Controlling the Number of Arms of Polymer Stars with a Fullerene C60 Core

Abstract

Pure di‐ and tetra‐adducts can be obtained by grafting polystyrene (PS) chains onto C₆₀ via an atom transfer radical addition. Stars with a C₆₀ core and exactly six PS arms of molar mass ranging from 1000 to several 100,000 are easily produced by adding an excess of PSLi to the fullerene. Tri‐ to penta‐adducts can be prepared by controlling the stoichiometry PSLi/C₆₀. The number of grafts on the fullerene can be extended to seven or eight by initiation of the anionic polymerization of an adequate monomer with a “living” hexa‐adduct or by grafting onto this latter an halogen terminated polymer.     

Temperature-dependent Thermodynamic Behaviors of Carbon Fullerene Molecules at Atmospheric Pressure

The study aims at investigating the linear and volumetric thermal expansion coefficients (CTEs) at temperature below the Debye temperature and phase transformation behaviors at atmospheric pressure of carbon fullerenes, i.e., C₆₀, C₇₀ and C₈₀, through a modified Nosé-Hoover (NH) thermostat method incorporated with molecular dynamics (MD) simulation. The calculated results are compared with those obtained from the standard NH and "massive" NHC (MNHC) thermostats and also with the literature experimental and theoretical data. Results show that at temperature below the Debye temperature, the CTEs of the fullerene molecules would significantly decrease with a decreasing temperature and tend to become negative at temperature below 5K. The present results are much more consistent with the literature experimental and theoretical data, in contrast to the other two thermostat algorithms. Besides, it is found that C₆₀ fullerene directly undergoes a solid-vapor phase transformation, instead of a solid-liquid phase transition, implying that the molecule will sublimate when heated rather than melt under atmospheric pressure. This phenomenon is coincident with that of graphite at pressures below 10MPa. The sublimation point of C₆₀ fullerene is about 4350±20K, comparable to that of graphite in the range of about 4000-4500K at pressures below 10 MPa.     

FORMATION OF FULLERENES AND CARBON CLUSTERS BY LASER IRRADIATION OF POLYMERIC FULLERENE OXIDE (FULLERENE OZOPOLYMER)

ABSTRACT

Polymeric fullerene oxide (PFO) prepared by prolonged ozonation of C₆₀ fullerene has been laser irradiated and the resulting products formed have been studied by ion cyclotron resonance mass spectrometry. It has been found that PFO produces a complete set of carbon clusters from C₆₀ up to C₁₆₄. The mechanism of formation of this set of fullerenic clusters implies necessarily a laser-induced carbonization step of the PFO substrate. Once the PFO target has been changed into the opportune carbon nanostructure by the laser radiation, the sequence of fullerene carbon clusters has been produced.     

Thermodesorption states of fullerene C60 in the polyimide-fullerene system

The data of thermodesorption mass spectrometry indicate that fullerene C₆₀ molecules are desorbed from a polyimide (PI) surface at temperatures below the PI decomposition onset temperature, while the desorption of C₆₀ from the bulk begins in the temperature region of the polymer decomposition. It is suggested that strong chemical bonds between C₆₀ and PI macromolecules are formed in the bulk in the stage of the polyamic acid preparation and are broken upon destruction of the polymer macromolecules. The character of C₆₀ thermodesorption from the PI surface depends on thickness of the surface film of fullerene C₆₀.     

Determination of C60 and/or C70 Concentrations

Abstract

Two methods of quantitative analyses of the fullerenes C₆₀ and C₇₀ are described. Quantitative Infrared Spectroscopy permits the determination of the concentrations of pure and mixed compositions of C₆₀ and C₇₀ in carbondisulfide solutions. Alternatively, the ratio of C₆₀/C₇₀ is analyzed by evaluating the lattice parameters of a solid solution of the fullerene species and cyclohexane according to Vegard's Law. Both methods show high accuracy and are suited for calibration of mass spectrometric analyses of fullerene samples.