Morphology linked to miscibility in highly amorphous semi-conducting polymer/fullerene blends

Molecular miscibility is a defining property of mixtures of electron-donating polymers and electron-accepting fullerenes used in the photoactive layer of bulk heterojunction (BHJ) organic solar cells. Even though miscibility of fullerene in the polymer is a commonly observed property, quantitative measurements have unknown connections with other morphological properties such as domain size and domain purity. By varying the amount of fullerene loading in BHJ thin films, we show that morphological properties are related to miscibility via straightforward relationships. In particular, miscibility influences the sensitivity of domain spacing to fullerene loading and determines the domain volume fractions and the residual fullerene content in the mixed polymer-rich phase in devices. Not only does this work show the relationships between miscibility and morphology, but it also highlights the general importance in determining miscibility levels in BHJ systems in order to target optimum morphologies and domain purities.     

Experimental study of industrial scale fullerene production by combustion synthesis

Fullerenes are expected to be one of the first carbon nanomaterials to be widely employed for various commercial applications. However, one critical factor that has limited the development of such applications is the high cost and limited availability of fullerenes. Much of this problem is due to the small-scale, batch nature of fullerene production using carbon arcs. In contrast, the combustion method generates soot with a very high yield of fullerenes using a continuous and easily scalable process. We have developed a combustion system that can produce fullerenes at the tons per year scale. Using this system, a laminar premixed flat sooting low-pressure toluene/oxygen flame that produced fullerenes was investigated, and we report the relation of the fullerene content and the combustion conditions such as the atomic C/O ratio, the cold burner gas velocity. When the atomic C/O ratio was higher, the fullerene content declined even though the fuel, pressure, and other combustion conditions were same. On the other hand, the fullerene content remained constant when the cold gas velocity was increased from 0.78 m/s to 1.7 m/s. We also discuss the data from a thermodynamic and equilibrium analysis point of view to gain insight into the fullerene formation process.     

Fullerene formation in an arc discharge

The unique properties of fullerenes have stimulated intensive research on fullerene-based materials for a wide range of applications, the hydrogen power industry being among them. However the high cost of fullerenes prevents their use for hydrogen storage. The only industrial method of fullerene production is arc discharge with graphite electrodes, but its optimum efficiency is far too low. Transformation of a chaotic carbon vapor into fullerenes is not well understood. It is known that carbon in the arc discharge region can only exist in the form of atoms or atomic ions. On the other hand, the location of the region, where the fullerenes arise, is also determined. No experimental research on the intermediate products, as applied to the arc discharge conditions, has been undertaken. The paper contains an attempt to develop a theory of fullerene formation, covering all the aspects of the problem, starting with arc discharge calculations, to the immediate fullerene molecule assembly.     

Electrochemical quartz crystal microbalance studies of thin-solid films of higher fullerenes: C76, C78 and C84

Thin-solid films of higher fullerenes, viz. C₇₆, C₇₈ and C₈₄, were prepared by the drop coating technique and characterized by simultaneous cyclic voltammetry and piezoelectric microgravimetry with the use of an electrochemical quartz crystal microbalance. Properties of the films were compared with those reported earlier for the C₆₀ and C₇₀ thin-solid films. The effect of nature of the counter cation on electrochemical properties of the films has been probed by employing acetonitrile solutions of two different 0.1 M supporting electrolytes, namely tetra(n-butyl)ammonium (TBA⁺) hexafluorophosphate and potassium hexafluorophosphate. Stability of the films with respect to dissolution depends on the fullerene oxidation state as well as on the nature of both the fullerene in the film and the counter cation in the supporting electrolyte. The TBA⁺ counter cation ingress to the film for compensation of the negative charge of the reduced fullerene is accompanied by the acetonitrile solvent intake. The number of acetonitrile molecules per TBA⁺ counter cation entering the film is higher the higher the fullerene. Also, the Langmuir films of higher fullerenes were prepared at the air-water interface and the film morphology was characterized by the Brewster angle microscopy.     

Fullerene Rosette: Two-Dimensional Interactive Nanoarchitectonics and Selective Vapor Sensing

The simplicity of fullerenes as assembled components provides attractive opportunities for basic understanding in self-assembly research. We applied in situ reactive methods to the self-assembly process of C₆₀ molecules with melamine/ethylenediamine components in solution, resulting in a novel type of fullerene assemblies, micron-sized two-dimensional, amorphous shape-regular objects, fullerene rosettes. ATR–FTIR spectra, XPS, and TGA results suggest that the melamine/ethylenediamine components strongly interact and/or are covalently linked with fullerenes in the fullerene rosettes. The broad peak for layer spacing in the XRD patterns of the fullerene rosettes corresponds roughly to the interdigitated fullerene bilayer or monolayer of modified fullerene molecules. The fullerene rosettes are made from the accumulation of bilayer/monolayer assemblies of hybridized fullerenes in low crystallinity. Prototype sensor systems were fabricated upon immobilization of the fullerene rosettes onto surfaces of a quartz crystal microbalance (QCM), and selective sensing of formic acid was demonstrated as preliminary results for social-demanded toxic material sensing. The QCM sensor with fullerene rosette is categorized as one of the large-response sensors among reported examples. In selectivity to formic acids against basic guests (formic acid/pyridine >30) or aromatic guests (formic acid/toluene >110), the fullerene rosette-based QCM sensor also showed superior performance.     

Inflammogenic effect of well-characterized fullerenes in inhalation and intratracheal instillation studies

Background

We used fullerenes, whose dispersion at the nano-level was stabilized by grinding in nitrogen gas in an agitation mill, to conduct an intratracheal instillation study and an inhalation exposure study. Fullerenes were individually dispersed in distilled water including 0.1% Tween 80, and the diameter of the fullerenes was 33 nm. These suspensions were directly injected as a solution in the intratracheal instillation study. The reference material was nickel oxide in distilled water. Wistar male rats intratracheally received a dose of 0.1 mg, 0.2 mg, or 1 mg of fullerenes and were sacrificed after 3 days, 1 week, 1 month, 3 months, and 6 months. In the inhalation study, Wistar rats were exposed to fullerene agglomerates (diameter: 96 ± 5 nm; 0.12 ± 0.03 mg/m³; 6 hours/days for 5 days/week) for 4 weeks and were sacrificed at 3 days, 1 month, and 3 months after the end of exposure. The inflammatory responses and gene expression of cytokine-induced neutrophil chemoattractants (CINCs) were examined in rat lungs in both studies.

Results

In the intratracheal instillation study, both the 0.1 mg and 0.2 mg fullerene groups did not show a significant increase of the total cell and neutrophil count in BALF or in the expression of CINC-1,-2αβ and-3 in the lung, while the high-dose, 1 mg group only showed a transient significant increase of neutrophils and expression of CINC-1,-2αβ and -3. In the inhalation study, there were no increases of total cell and neutrophil count in BALF, CINC-1,-2αβ and-3 in the fullerene group.

Conclusion

These data in intratracheal instillation and inhalation studies suggested that well-dispersed fullerenes do not have strong potential of neutrophil inflammation.     

Thermal and thermo‐oxidative stability of thermoplastic polymer nanocomposites with arylated [60]fullerene derivatives

Nanocomposite films of polystyrene (PS) and poly(methyl methacrylate) (PMMA) were prepared by loading four variations of fullerenes such as pristine C₆₀, multiarylated [60]fullerenes with tolyl (tolyl‐C₆₀) and phenol groups (phenol‐C₆₀), and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM). The TGA analysis showed no appreciable change in their thermal and thermo‐oxidative stabilities for PS/tolyl‐C₆₀ and PS/phenol‐C₆₀ films, but significant improvement up to +45°C for PS/C₆₀ and PS/PCBM films even under air. The thermo‐oxidative stability of PMMA/phenol‐C₆₀ and PMMA/PCBM, however, exhibited slightly larger improvements over that of PMMA/C₆₀. We believe that the radical‐scavenging ability of π‐conjugative fullerenes and the dispersibility of fullerene–polymer combinations play key roles in these enhancements. We also found that optimal loading occurred at a relatively low content of fullerenes (0.4–0.8 wt%) probably because larger amounts may interfere with the morphological interaction of polymer chains which is essential for the thermal persistency of polymer. POLYM. COMPOS. 37:1143–1151, 2016. © 2014 Society of Plastics Engineers     

由脱灰煤制备富勒烯

以 3种高变质程度的中国煤为原料 ,用电弧等离子体蒸发法制备富勒烯 .富勒烯产品的表征采用质谱、紫外光谱和红外光谱等技术 .采用碱法脱灰技术对 3种煤进行脱灰处理 ,考察了脱灰前后煤样的灰分和相应炭棒中碳含量对富勒烯产率的影响 .结果表明 ,由实验所用煤种均可制得富勒烯 .原料煤本身的化学结构和组成对富勒烯的产率有明显影响 ,表现为富勒烯的产率随炭棒中碳含量的增加而增大 .煤中的矿物质对富勒烯的形成有很强的抑制作用 ,表现为富勒烯的产率随原料煤中灰分的增加而降低 ,这一变化趋势通过对介休焦煤进行不同程度的脱灰处理而得到进一步证实.     

Chemical redox recovery of giant, small-gap and other fullerenes

A simple method for extracting otherwise insoluble fullerenes into organic solvents is presented. The fullerenes are reduced to anionic charge states by contact with zinc in the presence of an alkylphosphonium salt in tetrahydrofuran. The anionic fullerenes become soluble, and the non-fullerene carbon matrix is separated by filtration. The anionic fullerenes can then be precipitated from solution by the action of a chemical oxidant such as iodine. It is also shown that there are approximately as many fullerenes left behind in carbon arc soot after solvent extraction as are extracted by the solvent. In contrast, more than twice as many fullerenes are left behind in combustion-produced fullerene soot as are solvent-extracted. Thus, approximately 70% of the total recovered carbon product from large-scale combustion synthesis is fullerenes. Conversely, no detectable amount of fullerenes can be recovered from conventional carbon blacks under the same conditions. Analysis by single photon ionization mass spectrometry suggests that C₆₀ and C₇₀ account for almost half of the fullerenes that were not solvent-extractable, suggesting that they are readily incorporated into toluene-insoluble fullerene polymers. The redox process presented here is easily up-scaled, and we routinely recover 100 g of heretofore insoluble fullerenes in 8 h.     

Polyether-modified fullerenes

Summary Polyether-modified fullerenes have been prepared under mild conditions by reacting C₆₀ or C₇₀ in toluene with a precursor poly(oxyethylene) or poly(oxypropylene) polymer possessing amino end-groups. In the early stages of the interaction, soluble products are formed. Later, cross-linking proceeds between the polyfunctional fullerenes and the bifunctional polyethers. The non-crosslinked fullerene derivatives are soluble both in toluene and water; by evaporation of toluene, very adhesive films are formed.     

Symmetrical features of the structure of C<Subscript>24</Subscript> and C<Subscript>48</Subscript> fullerenes

Structural features of the C₂₄ fullerene and two C₄₈ fullerene isomers with the noncrystallographic point symmetry group D _6d have been considered. The fundamental domains, Schlegel diagrams, and adjacency graphs of structural elements of the fundamental domains have been constructed. It has been revealed that all fullerene faces are pentagons or hexagons but not all of these polygons are regular. The number of pentagonal faces in all fullerenes under consideration is 12, the number of hexagonal faces in the C₂₄ fullerene is 2, and the number of hexagonal faces in the C₄₈ fullerenes is 14. The fundamental domains for all the fullerenes under investigation are not closed because they include the twofold axis of rotation.     

Syntheses and properties of macromolecular fullerenes,a review

The recent progress and prospects of macromolecular fullerenes with respect to their syntheses and properties are compiled and discussed. The variety of macrofullerenes with emphasis on C₆₀ and C₇₀ is presented and synthetic concepts of polymer derivatives of fullerenes are outlined. After a concise consideration of the fundamentals of fullerene reactivity, both major types of fullerene-containing polymers, main-chain and side-chain polymers, together with special types, such as telechelic, macrocyclic, dendrimeric and star-shaped fullerene materials, are covered. Also, the synthesis of fullerene-containing copolymers via radical polyreactions and preparative aspects of surface-attached fullerenes are described. The properties of the macromolecular fullerene derivatives are discussed in view of their structure and application. Finally, the role of macrofullerenes for new materials or their precursors is elucidated. © 1999 Society of Chemical Industry     

Study of the Desensitizing Effect of Different [60]Fullerene Crystals on Cyclotetramethylenetetranitramine (HMX)

Three types of [60]fullerene crystals were obtained. The first one was the direct commercial [60]fullerene, and the other two were recrystallized from the first one in carbon bisulfide and in carbon bisulfide/petroleum ether, respectively. Scanning electron microscopy (SEM), X‐ray powder diffractometry (XRD), and FT‐IR spectrometry were used to study the physical characteristics of the crystals. The thermal stability of the three [60]fullerene crystals was studied by differential thermal analysis (DTA), and the effects of the three [60]fullerenes on the mechanical sensitivity and friction sensitivity of HMX were tested and analyzed. It was found that the three types of [60]fullerenes have different thermal stabilities, and the friction and impact sensitivities of HMX are reduced from 100% to 70% and to 60%, respectively when 1% [60]fullerene 3 was added in HMX.     

Genotoxic Anti-Cancer Agents and Their Relationship to DNA Damage,Mitosis, and Checkpoint Adaptation in Proliferating Cancer Cells

When a human cell detects damaged DNA, it initiates the DNA damage response (DDR) that permits it to repair the damage and avoid transmitting it to daughter cells. Despite this response, changes to the genome occur and some cells, such as proliferating cancer cells, are prone to genome instability. The cellular processes that lead to genomic changes after a genotoxic event are not well understood. Our research focuses on the relationship between genotoxic cancer drugs and checkpoint adaptation, which is the process of mitosis with damaged DNA. We examine the types of DNA damage induced by widely used cancer drugs and describe their effects upon proliferating cancer cells. There is evidence that cell death caused by genotoxic cancer drugs in some cases includes exiting a DNA damage cell cycle arrest and entry into mitosis. Furthermore, some cells are able to survive this process at a time when the genome is most susceptible to change or rearrangement. Checkpoint adaptation is poorly characterised in human cells; we predict that increasing our understanding of this pathway may help to understand genomic instability in cancer cells and provide insight into methods to improve the efficacy of current cancer therapies.     

Effects of fullerene addition on the carbonization of synthetic naphthalene isotropic pitch

The toluene soluble fraction of fullerene soot, consisting of C₆₀ and C₇₀ and other fullerenes, was co-carbonized with synthesized isotropic pitch derived from naphthalene. Mixtures of fullerene and pitch gave carbons in higher yield than expected from their single carbonizations at fullerene contents <30 wt%. The fullerenes suppressed the expansion of the pitch during carbonizations, and changed the optical textures of resultant carbons. At levels of addition of fullerenes <30 wt%, no fullerenes could be detected in resultant carbons by spectroscopy, but were detected as spheres of ca. 10–20 nm diameter in the carbons by TEM. It is considered that fullerenes remove hydrogen from the naphthenic structures of the pitch and so alter carbonization characteristics. Hydrogenation breaks the spheroidal fullerene framework.     

Reaction rate coefficient of fullerene (C60) consumption by soot

The reaction of fullerene molecules with soot was studied by contacting sublimed C₆₀ fullerenes with commercially available carbon black particles at different temperatures in the range 1023-1273 K. Fullerene mass data collected both pre- and post-reaction were fit to a simple first-order kinetic model and yielded a temperature-dependent reaction rate expression. The calculated collision efficiency of the reaction is of the order 10⁻⁸ and the activation energy is ∼9.8 kcal mol⁻¹, which would be consistent with a surface diffusion reaction or a heterogeneous reaction. Simple extrapolation of the observed rate to the conditions of a fullerene forming flame would give a consumption rate six orders of magnitude too small to account for the rate of fullerene consumption observed in the post-flame zone of a fullerene-forming benzene/oxygen/argon flame. Extrapolation of the reaction rate to flame conditions also shows that the rate of consumption calculated here is too small to account for observed oscillations in the fullerene concentration profile which can be related to changes in the relative rates of consumption and formation. Calculation of activation energies required for the extrapolation of rates observed here to match those observed in flames yields significantly larger values than those obtained in the present study and are so large as to suggest that mechanisms other than those studied here control fullerenes consumption in flames. Other mechanistic possibilities for the consumption of fullerenes in flames include reactions of fullerenes with other flame species and fullerene-soot reactions in which soot reactivity depends on soot reactions with other flame species.     

5-Fu对人结肠癌细胞凋亡过程中DNA损伤修复基因表达的影响

目的探讨5-Fu对人结肠癌细胞(HCT/8)凋亡过程中DNA损伤修复相关基因表达的影响。方法通过形态学、基因组电泳、吖啶橙染色及流式细胞仪,观察大肠癌细胞凋亡情况,同时应用基因芯片分析5-Fu作用后DNA损伤修复相关基因表达的变化。结果经流式细胞仪检测发现,5-Fu作用于HCT/8细胞48h与对照组相比,凋亡细胞数明显增加,基因组电泳出现典型的梯形条带,基因芯片分析显示,12个与DNA损伤修复相关的基因中,上调基因3个,下调基因9个。结论5-Fu作用于结肠癌细胞,导致多种DNA损伤修复基因发生改变,综合作用使细胞不能及时对损伤DNA进行修复,最终导致细胞发生凋亡。     

The relationship of biochemical and morphological information in the central nervous system: The problem of sampling

The histology of the central nervous system (CNS) is complex, consisting of membranes derived from a number of cell types as well as specialized membranes associated with structural modifications of the neuron. The cell structure, and thus the membrane content, of the CNS varies with age and from area to area; in no instance is it possible to isolate a single cell type without special microdissection techniques. Neurological disease often involves specific areas of the CNS attacking one or all of the cellular elements in that region. In other instances, damage may be wide-spread, but at the histological level it may be restricted to a single cell type or even to a single membrane. The latter situation is particularly applicable to diseases that attack the myelin sheath. The biochemical investigation of changes in the lipid content of the brain resulting from neurological disease is hampered not only by the morphological complexity of nervous tissue, but by the tendency of destructive processes to be accompanied by proliferation of other cellular elements, both during the acute phase of disease and during the process of repair, which may mask significant abnormalities. Thus, in order to decide which changes in the structural lipids of the diseased brain are meaningful, a knowledge of the histopathology of the disorder is essential. When the morphological changes that accompany a neurological disorder are known, one may choose an appropriate tissue sample for study. Isolation of specific structural or functional subunits of the CNS, dissection of small groups of cells, isolation of single cells and separation of specific membranes are techniques available to sample nervous tissue. These are discussed, and their applicability to the biochemical study of specific neurological diseases is evaluated.     

C60 encapsulation inside single-walled carbon nanotubes using alkali-fullerene plasma method

It is reported that alkali-fullerene plasmas consisting of positive alkali-metal ions, negative fullerene ions, and residual electrons are effective in encapsulating fullerenes inside single-walled carbon nanotubes (SWNTs). When positive or negative bias-voltages are applied to SWNTs in plasmas, accelerated negative fullerene or positive alkali-metal ions are irradiated to the SWNTs through the plasma sheath, respectively. Field emission gun transmission electron microscopy (FEG-TEM) clearly shows that drastic structural modifications such as severe bending of SWNT bundles, tube dislocation, and tube tip termination take place after the ion irradiation. Energy dispersive X-ray spectrometry (EDS) confirms the existence of the alkali-metal elements in the sample after the alkali-metal irradiation. In addition to this, the SWNTs encapsulating fullerene molecules are directly observed after only 1 h fullerene-ion irradiation. These results suggest that our experimental system could permit us to intercalate not only fullerenes but also other elements inside the SWNTs by the applied-bias control. Raman scattering spectroscopy is also adopted for the purpose of evaluating pure SWNTs and fullerene encapsulated SWNTs.     

Magnetic properties of nanocarbon

Our experimental results provide the evidence that ferromagnetic properties of polymerized fullerenes are of non-trivial origin. Comparison of magnetic measurements, impurity analysis and Raman spectroscopy proves that in certain cases the sample structure affects the magnetic ordering. We provide the explanation of the results obtained of fullerenes within the model of charged fullerenes, where the charge comes from various defects and impurities. It is important that the impurities do not have to be magnetic: even carbon impurity in the all-carbon fullerene network can act as a magnetic trigger.