Addition Of C60 Research Articles

Studying electronic transport in polyazulene–ionic liquid systems using infrared vibrational spectroscopy

This paper presents an in situ spectroelectrochemical characterization of polyazulene (PAz) and PAz-C(60) composite films using Fourier Transform Infrared Attenuated Total Reflection (FTIR-ATR) spectroscopy. In situ FTIR-ATR spectra were recorded simultaneously as the films were charged and discharged electrochemically. The aim was to clarify how the use of ILs and the addition of C(60) affected the electronic transport and structural changes occurring in PAz during electrochemical charging. We found that electrosynthesis of PAz in an IL lowered the oxidation potential of the film and improved its electroactivity. The FTIR-ATR data also suggest that PAz with a longer effective conjugation length is obtained during electrosynthesis when using ILs. With in situ FTIR-ATR it is possible to quite accurately determine the onset potential for oxidation/reduction. These values are important since they determine the suitability of the polymer for a specific application. Our experiments indicate that two types of charge carriers are formed during electrochemical oxidation of PAz in an IL. Furthermore, their formation is strongly affected by the addition of C(60) into the film. The type of charge carrier formed affects the electronic and possibly also ionic transport within the film. The inclusion of C(60) into PAz influenced the optical and structural properties considerably. In situ FTIR-ATR is also an extremely useful method for studying the potential stability of an IL during electrochemical cycling. We showed that cathodic decomposition of N,N-butyl-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMP][Tf(2)N]) occurs at less negative potentials than those determined electrochemically.

ExTTF-capped gold nanoparticles as multivalent receptors for C60

We report the synthesis and C60 binding abilities of gold nanoparticles capped with π-extended tetrathiafulvalene (exTTFAuNPs). The exTTFAuNPs show a strong tendency to aggregate both in solution and in the solid state through multiple weak exTTF-exTTF interactions. A thorough collection of experiments demonstrates that upon addition of C60, stable noncovalent exTTFAuNP·C60 associates are formed, with concomitant partial disaggregation of the nanoparticles.

Improvement of the critical current density of spark plasma sinteredMgB2 byC60 addition

We investigated the influence of fullerene (C60) addition on the superconducting parameters ofMgB2 bulk samples obtained by spark plasma sintering (SPS). It was found that 1.5 wt%C60 addition leads to the reduction of the critical temperature by a few K,whereas the magnetically determined critical current density increasesby approximately one order of magnitude in an applied magnetic fieldH = 70 kOe attemperature T = 10 K. This indicates substitution of B by C inC60 addedMgB2 processed by SPS, contrary to some data reported in the literatureobtained using conventional methods. For our relatively large specimens,the occurrence of macroscale flux jumps was observed over a wide (H, T) domain. The relaxation of the irreversible magnetization suggests that themacroscale flux jumps transform into microscale flux jumps with increasingH andT.

Effect of C60 on the Photocatalytic Activity of TiO2 Nanorods

C60-incorporated TiO2 nanorods were prepared in a hydrothermal process. Rhodamine B (RhB) as a model pollutant was used to probe the photocatalytic activity of products. The results showed that the photocatalytic activity of TiO2 nanorods incorporated with C60 under visible light irradiation markedly increased by a factor of approximately 3.3 when compared with pure TiO2 nanorods and approximately 2.7 when compared with Degussa P25, respectively. The enhanced photocatalytic activity under visible light irradiation may be ascribed to an effective separation of the photoexcited electrons due to the addition of C60.

English

The influence of fullerene additives on the combustion behaviour of cyclotrimethylene trinitramine/ammonium perchlorate composite modified double-base (RDX/AP-CMDB) propellants are investigated by thermogravimetricdifferential thermogravimetric (TG-DTG) analysis, burning rate tests, and scanning electron microscopy observations. The difference between lead salicylate (F-Pb) and bismuth citrate acid (CP-Bi) as combustion modifiers has also been examined. TG-DTG investigations show that the addition of all additives advanced and accelerated the evaporation of nitroglycerin (NG). The addition of Extracted Fullerene Soot (EFS), C60 and carbon black (CB) additives obviously accelerated the liquid phase decomposition of NG. Also, the solid phasedecomposition of nitrocellulose (NC) and the liquid phase decomposition of RDX were accelerated by 0.5 per cent Fullerene Soot (FS)/2.5 per cent CP-Bi/0.5 per cent copper adipic acid (J-Cu) composite catalyst. The addition of all composite catalysts promoted the decomposition of ammonium perchlorate (AP) except 0.5 per cent EFS/2.5 per cent CP-Bi/0.5 per cent J-Cu composite catalysts. It is well known that there exists dark zone in the flame structure of RDX-CMDB propellant, but in our observation, the dark zone vanished with the addition of 10 per cent AP to the forenamed propellant. The burning rates were increased at low pressure but reduced at high pressure by all catalysts except 0.5 per cent EFS/2.5 per cent CP-Bi/0.5 per cent J-Cu and 0.5 per cent C60/2.5 per cent CP-Bi/0.5 per cent J-Cu which reduced the burning rates at every tested pressure. The pressure exponents of tested propellants were reduced by 0.5 per cent FS/2.5 per cent CP-Bi/0.5 per cent J-Cu with a factor of 17 per cent . The quenched surface observations significantly differed with the additions of diverse composite catalysts, which were consistent with the burning rate results.Defence Science Journal, 2009, 59(3), pp.284-293, DOI:http://dx.doi.org/10.14429/dsj.59.1522

Dielectric Spectroscopy Investigation of Relaxation in C60−Polyisoprene Nanocomposites

We investigate the influence of adding C60 nanoparticles on the dielectric relaxation spectra of both unentangled and entangled polyisoprene (PIP). Relaxation modes corresponding to both the segmental and chain relaxation were analyzed over a broad temperature and frequency range. Regardless of whether the chains were entangled or not, both relaxation processes slowed down with the addition of C60, reflecting an increase of the nanocomposite glass transition temperature. However, C60 affects the segmental relaxation more strongly than the large-scale chain relaxation, both in terms of the relaxation time and strength, suggesting that the effect of the nanoparticles on the polymer dynamics is scale dependent. This effect is attributed to a difference in packing frustration at different length scales, a phenomenon also relevant to understanding the difference between the temperature dependence of the segmental and chain relaxation processes in neat polymer materials. Further evidence of this scale dependence is indicated by the observation that the secondary relaxation time of the high molecular mass PIP decreases with an addition of C60. These observations indicate that C60 has an effect opposite to antiplasticizing additives that slow down the secondary relaxation (stiffening the material) in the glass state, while at the same time reducing the alpha relaxation time associated with cooperative segmental and chain motions. Recent incoherent neutron scattering measurements have indicated that C60 can have a similar effect on polystyrene.

C60 Modification of Al Anode for Efficient Hole Injection in Organic Light-Emitting Diodes

An Al:C60 composite anode structure was developed to improve hole injection in organic light-emitting diodes. Work function of Al was shifted from 4.3 eV to 5.2 eV by the addition of C60 because of complex formation between C60 and Al. The current density in the device was improved by 10 times by using a composite anode structure because of low hole injection energy barrier between the composite anode and hole transport layer.

Structure and Transport Properties of Fullerene–Polyamide Membranes

Poly‐(phenylene‐iso‐phtalamide) was modified by fullerene C60 and other nanocarbon additives such as nanotubes and soot. These compositions were used for ultrafiltration membranes formation. To estimate the fullerene effect on polyamide properties, intrinsic viscosity and density of compositions containing up to 10 wt% C60 were measured. In addition, overall porosity of asymmetric membranes and contact angle of water on membranes surface were determined. Membranes structure rigidity and resistance to different solvents were estimated by filtration of liquids with different viscosities through membranes modified by 5 wt% fullerene, soot or nanotubes. All nanocomposite membranes were tested in dynamic (ultrafiltration) and static sorption experiments with solution of proteins mixture with different molecular weights to study proteins sorption. Membranes modified by fullerene and nanotubes demonstrated the best values of flux reduced recovery after contact with proteins solution.

Plasticization effect of C60 on the fast dynamics of polystyrene and related polymers: an incoherent neutron scatteringstudy

We utilize inelastic incoherent neutron scattering (INS) to quantify how fullerenes affectthe ‘fast’ molecular dynamics of a family of polystyrene related macromolecules. Inparticular, we prepared bulk nanocomposites of (hydrogenous and ring-deuterated)polystyrene and poly(4-methyl styrene) using a rapid precipitation method where theC60 relative mass fraction ranged from 0% to 4%. Elastic window scan measurements, using a high resolution(0.9 µeV) backscattering spectrometer, are reported over a wide temperature range (2–450 K).Apparent Debye–Waller (DW) factors , characterizing the mean-square amplitude of proton displacements, are determined as a function of temperature,T. We find thatthe addition of C60 to these polymers leads to a progressive increase in relative to the pure polymer value over the entire temperature range investigated, where theeffect is larger for larger nanoparticle concentration. This general trend seems to indicate that theC60 nanoparticlesplasticize the fast (≈10−15 s) local (≈1 Å) dynamics of these polymer glasses. Generally, we expect nanoparticle additives to affectpolymer dynamics in a similar fashion to thin films in the sense that the high interfacialarea may cause both a speeding up and slowing down of the glass state dynamicsdepending on the polymer–surface interaction.

Inhibition of DNA restrictive endonucleases and Taq DNA polymerase by trimalonic acid C60

Activities of trimalonic acid fullerene (TMA C60) on DNA restrictive enzymatic reaction were investigated by using two restrictive endonucleases Hind III and EcoR I and plasmid pEGFP-N1 with single restrictive site for both enzymes. Meanwhile, TMA C60 was also tested to clarify its effects on polymerase chain reaction (PCR) with the catalyst of Taq DNA polymerase and the template of plasmid pEGFP-N1. The products from restrictive reactions or PCR were detected by agarose gel electrophoresis. It was found that the product amounts from restrictive reactions or PCR decreased significantly with addition of TMA C60. The inhibition by TMA C60 was dose-dependent and IC50 values for reactions of Hind III, EcoR I and PCR were 16.3, 6.0 and 6.0 μmol/L, respectively. Addition of two scavengers of reactive oxygen species (ROS), L-ascorbic acid-2-phosphate ester magnesium and sodium azide at the concentrations of 2–10 mmol/L did not antagonize the activities of TMA C60 against PCR and two restrictive reactions. However, increase of Taq DNA polymerase amounts in PCR system antagonized the activities of TMA C60. These data implied that TMA C60 was able to inhibit the activities of the three above-mentioned enzymes involved in DNA metabolism, and that this inhibition probably did not correlate to ROS.

Poly(L‐lactide)/C60 nanocomposites: Effects of C60 on crystallization of poly(L‐lactide)

AbstractThe effects of solvent type and concentration of C60 on the crystallization of poly(L‐lactide) (PLLA) during solvent evaporation, heating from room temperature, and cooling from the melt were investigated by polarized optical microscopy and differential scanning calorimetry. The addition of C60 enhanced the PLLA crystallization during solvent evaporation, during heating of the melt‐quenched films, and during cooling from the melt of As‐cast films, except for heating and cooling of the PLLA film with 1 wt % of C60 prepared with dichloromethane. In the case of solvent evaporation, the difference in crystallinity between the PLLA films with and without C60 became higher for the solvent with a lower boiling point. In the case of heating of melt‐quenched films, the addition of C60 had a small effect on the crystallinity of PLLA, whereas significantly lowered the peak top and ending temperatures of cold crystallization, except for melt‐quenched PLLA film with 1 wt % of C60 prepared with dichloromethane. The crystallinity of PLLA was determined by the solvent type, rather than by the C60 concentration. In the case of cooling from the melt of As‐cast films, the addition of C60 elevated the crystallinity and cold crystallization temperature values of PLLA films, except for PLLA films prepared with dichloromethane. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2167–2176, 2007

Inhibition of M-MuLV reverse transcriptase activity by fullerene derivatives

Influence of fullerene (C60) derivatives on M-MuLV reverse transcriptase activity is investigated. Two water-soluble fullerene derivatives, fullerol (C60(OH)23–24) and trimalonic acid C60 (TMA C60, C63(COOH)6) are used in the experiments and their effects on in vitro reverse transcription-polymerase chain reaction (RT-PCR) of β-actin mRNA in HeLa cells are determined. PCR products are detected by agarose gel electrophoresis. It is found that the amounts of PCR products decrease with addition of either of two fullerene derivatives to RT reaction mixture. The inhibition of fullerene derivatives is dose-dependent, and IC50 values of fullerol and TMA C60 are 0.089 and 0.039 mmol/L, respectively. The amount of PCR products obtained by direct addition of fullerol or TMA C60 to PCR are greater than those obtained by addition of the equivalent amount of fullerol or TMA C60 to RT, indicating an inhibitory effect of fullerol or TMA C60 on RT. The compensative experiment of M-MuLV reverse transcriptase shows that increasing enzyme amounts can antagonize the activity of fullerol or TMA C60. These results imply that fullerenes can inhibit M-MuLV reverse transcriptase activity, with the inhibition of TMA C60 slightly stronger than fullerol, and that their potential in treatment of diseases induced by RNA viruses such as leukemia virus needs further investigation.

Enhanced hole transport in C60-doped hole transport layer

The carrier mobility of C60-doped hole transport layer was investigated according to the C60 content. The addition of C60 in the 1, 3, 5-tris (N, N-bis-(4, 5-methoxyphenyl)-aminophenyl) benzol (TDAPB) hole transport material resulted in the increase of hole mobility of TDAPB. The C60 molecule acted as a p-type dopant in the hole transport layer, resulting in the improved hole transport in TDAPB. The hole mobility of C60-doped TDAPB was 9.0×10−4cm2∕Vs compared with 1.0×10−4cm2∕Vs for nondoped TDAPB.

Effect of carbon nanomaterials on calcium carbonate crystallization

The addition of the water-soluble carbon nanomaterials, fullerenol (C60(OH)n), hydroxylated single walled carbon nanotubes (HO-SWNTs) and isophthalic acid functionalized-SWNTs (IPA-SWNTs), alter the morphology and crystal phase of CaCO3 precipitates form aqueous solution. CaCO3 precipitation in the presence of C60(OH)n results in the formation of spherical features, 5-pointed flower shaped clusters, and triangular crystals as opposed to the usual rhombic crystals. In addition, the meta-stable vaterite phase is observed with the addition of C60(OH)n. The effect on crystal growth of the C60(OH)n is not a simple function of the pH of the solution, although it may be due to reactivity of the hydroxyl groups. Precipitation with water-soluble HO-SWNT and IPA-SWNTs produces CaCO3 coated SWNTs with the CaCO3 being amorphous rather than crystalline.

Inertness of C60 fullerene toward RO2 · peroxy radicals

The reactivity of fullerene C60 toward peroxy radicals RO2· was tested by the chemiluminescence method. A comparison of the influence of C60 and known inhibitors on the kinetics of liquid-phase chemiluminescence (CL) during oxidation of a series of hydrocarbons (ethyl-benzene, cyclohexane, n-dodecane, and oleic acid) shows that the fullerene does not react with the RO2· radicals. A sharp decrease in the CL intensity observed upon C60 addition is caused by the quenching of CL emitters with fullerene but not by inhibition of hydrocarbon oxidation.

Effects of carbon nanosolids on the electro-optical properties of a twisted nematic liquid-crystal host

We present results of the electro-optical effect in 90° twisted nematic cells of pristine and doped liquid crystals under an applied dc voltage. The doped cells were fabricated with a minute addition of either buckminsterfullerene C60 or multiwalled carbon nanotubes (CNTs). Investigated were the switching behaviors as well as the hystereses and time evolutions of both the optical transmittance and electrical capacitance of the display samples. It is shown that doping with nanotubes can effectively reduce the dc driving voltage and improve the switching behavior.

Ab initio study of C60–silicon clusters

We report on the energetics of C60–Si clusters. By means of ab initio calculations based on the local density approximation to the density functional theory, we have investigated stable and metastable structures of C60–Si, C60–Si–C60, and (C60–Si)2 clusters. In each case, we show that silicon preferentially binds to C60 over a carbon–carbon double bond, in accordance with calculations on the interaction of C60 with silicon surfaces. This bonding is characterized by a partial charge transfer from silicon to C60. We show that the interaction between C60 and silicon is local and not perturbed by the addition of more C60–Si clusters or C60 molecules. The binding energy for stable and metastable (C60–Si)n⩽2 systems is high enough (several eV) to open the prospect of synthesizing nanostructured films from the C60–Si unit. Furthermore, in all three cases, the silicon position on a fivefold symmetry axis is found to be a metastable position. The nature and structure of nanostructured films resulting from the deposition of these clusters is qualitatively discussed.

Antiwear Effect of Fullerene C60 Additives to Lubricating Oils

The protective film (≤1000 A thick) formed on the copper foil surface upon friction of a steel roller lubricated with industrial oil containing 5% fullerene C60 was studied by optical and electron microscopy, X-ray diffraction (XRD) analysis, hardness measurements, and mass spectrometry. This protective film is probably a fullerene-polymer network formed by fullerene C60 and covalently bound fragments of hydrocarbon chains released in the course of mechanochemical degradation of the lubricating oil. The film exhibits elevated hardness and antiwear properties, and increases the load-carrying power of the tribotechnical unit. Chemical mechanisms of tribopolymerization were analyzed.

An electron microscopy study of a copper surface during the sliding boundary friction in the presence of fullerene C60

The structure of a protective film formed on the copper counterbody surface during the sliding boundary friction in the presence of fullerene C60 additives in a lubricant oil was studied by transmission electron microscopy and electron diffraction.

Investigation of the Stabilizing Action of Mixtures of Fullerene C60 with Known Antioxidants in the Thermo-oxidative Degradation of Polystyrene

Investigations have been made on the effects of double mixtures of C60 with well-known antioxidants (amines, phenols, S- and P-containing compounds, Ph3Sb) on the thermo-oxidative degradation of PS by DSC method under oxygen. The influence of mixtures on the temperature of the onset of polymer degradation, T 0, has been studied. The effects of concentration of C60 on the value of the temperature limit of inhibition of PS thermo-oxidative degradation by known antioxidants, T 0 max, have been investigated. It has been shown that mixtures of C60 with Ph3Sb and phenyl-β-naphthylamine have a synergistic effect upon T 0. At a total concentration of 1.4 × 10−2mol/kg, the maximum value of T 0 is observed at a molar C60: compound ratio of 3:4 and 1:2.5 for the mixtures of C60 with Ph3Sb and phenyl-β-naphthylamine, respectively. Addition of C60 to these compounds leads to an increase in T 0 max for Ph3Sb and phenyl-β-naphthylamine. The suggestion was made that in the case of mixtures of C60 with Ph3Sb, the synergistic effect is Associated with different mechanisms of stabilizing action of the components on PS degradation, namely C60 reacts with alkyl and oxygen-containing radicals with the formation of more stable compounds while Ph3Sb decomposes polymeric and fullerene-containing peroxides and hydroperoxides. The decomposition of Ph3Sb was investigated by DSC method under oxygen. The temperature of the onset of Ph3Sb degradation was shown to be 362.5°C. It was concluded that further investigations are necessary for understanding the synergistic action of mixture of C60 with phenyl-β-naphthylamine in the thermo-oxidative degradation of PS.