Variation of optical properties,rheology, and microstructure in fullerene/poly(vinyl pyrrolidone) nanofluids with fullerene content in n-butanol

In this study, we report non-linear variation of optical and rheology properties in fullerene (C₆₀)/poly(vinyl pyrrolidone) (PVP) nanofluids (NFs) with C₆₀-content (C) in an alcoholic medium. From the absorption spectra, we found that the absorbance maximum (α_max) follows a non-linear path with C-value due to a donor–acceptor PVP → C₆₀ charge transfer in a C₆₀/PVP complex. The α_max value reaches maximum at a specific C₆₀-content of 13.9 μM due to percolation effect and then starts decreasing with a further increase in C-value over the subsequent region covered in this experiment. Models were proposed to show donor–acceptor interaction between C₆₀ and PVP. The molar extinction coefficient also drops through a peak maximum at 13.9-µM C₆₀. Regardless of the C-values, shear-thinning behavior was found in all NFs. The shear viscosity (η) value, which decreases with shear rate value over 5 to 100 s^?1, is shown to be increasing non-linearly against the C-value. The η-value varies non-linearly with C₆₀-content and shows a dip at a point near 13.9-µM C₆₀. High-resolution transmission electron microscope images reveal that the size of C₆₀/PVP nano-assemblies increases with C-value as PVP is anchoring C₆₀ molecules in specific structures.     

Synthesis and Complex Study of Water‐Soluble Polymer Derivatives of C60 Fullerene

Abstract

The water‐soluble composites with fullerene content up to 5 wt% based on poly‐(N‐vinylpyrrolydone) (PVP) were obtained. The higher fullerene content is achieved by means of introducing tetraphenylporphyrine (TPP) and KBr into composites. The synthesis includes the formation of C₆₀–TPP complex and its further interaction with polymer. The formation of C₆₀–TPP complex was confirmed by ¹³C NMR, SANS, and translational diffusion. The hydrodynamic and electrooptical studies of C₆₀–TPP–PVP complexes indicate the higher symmetry of the polymer coil in the complex as compared to PVP. The C₆₀–PVP–KBr composites were also obtained by the solid state interaction under vacuum, KBr promoting the destruction of fullerene aggregates.     

Morphological,optical, structural and photoelectrochemical properties of TiO2 nanoflower prepared via PVP surfactant assisted liquid phase deposition technique

This paper reports the synthesis of TiO₂ nanoflowers as photovoltaic materials of the photoelectrochemical cell (PEC) via the phase liquid deposition technique assisted with a polyvinylpyrrolidone (PVP) surfactant. This work investigates the influence of the surfactant concentration on the morphological, optical, phase structure and PEC properties of the TiO₂ PEC cell. The grain size of the TiO₂ sample decreases with increase in PVP concentration. The smallest grain size of 16 ± 2 nm is obtained at 8 mM PVP. The thickness of the sample increases with PVP concentration. The concentration of PVP does not influence the optical absorption and band gap of the sample. The phase structure and crystallinity degree of the sample are not influenced by PVP concentration. The crystallite size is around 20 nm. The short-circuit current density, J_sc, of the PEC cell utilising these TiO₂ samples increases with decrease in grain size which is due to the increase in PVP concentration. The best J_sc was 0.068 mA cm^?2 obtained at 8 mM PVP.     

Light scattering in water solutions of fullerene-containing polymers: Part 2. Effect of the molecular weight of the carrier polymer

The effect of the molecular mass M _PVP of linear polyvinylpyrrolidone macromolecules on the structures of domains formed in water solutions of PVP/fullerene (C₆₀) complexes is investigated. For constant C₆₀ concentration in a complex, the values of M _dom, starting at M _PVP=20×10³, increase as M _PVP ^1.7 , attesting to the formation of a fluctuation network whose nodes are C₆₀ molecules. Pis’ma Zh. Tekh. Fiz. 25, 45–49 (October 12, 1999)     

New Molecular Complex of Fullerene C60 with Porphyrin Dimer [FeTPP]2O: Synthesis and Crystal Structure

Abstract

New molecular complex of C₆₀ with covalently linked (Fe^IIITPP)₂O · C₆₀ dimer has been obtained. The complex has isolated packing of fullerenes in which fullerene molecule is embraced in a pocket built by porphyrins. (Fe^IIITPP)₂O preserves its initial geometry in the complex. The Fe···C(C₆₀) contacts are in the 3.239–3.513 Å range indicating the absence of Fe–C₆₀ coordination. This results in the similarity of the EPR spectra of the complex and parent (Fe^IIITPP)₂O.     

Superstructures of Polymeric Stars with Fullerene Core in Solutions

Abstract

Poly(styrene) stars (PS)₆C₆₀, twin‐cores (PS)₆C₆₀‐[Si‐(CH₃)₂]‐C₆₀(PS)₆ and hybrids (PS)₆C₆₀(PTBMA)₆ with paired arms of PS + poly(tertbutylmethacrylate) have been studied in toluene (20°C, concentration C = 1–6 wt.%) by small‐angle neutron scattering (SANS) at momentum transfer q = 0.001–5 nm^?1. The C₆₀ stabilize arms' stretched conformation and intensify stars' ordering. While the (PS)₆C₆₀ and hybrids formed tiny clusters (particles' number N ～ 10–80, size R _C ～ 50–100 nm), the dimers created massive structures (N ～ 1 · 10³–2 · 10³, R _C ～ 300 nm) that can be induced by dipolar interaction of C₆₀ twin‐cores.     

Ion–Ion Collisions Involving Fullerene Ions

Abstract

Fullerenes are a direct link between atoms with discrete electronic energy levels and solids with a band structure and a well defined surface. In collision experiments, both between energetic ions or electrons and neutral C₆₀ molecules [Walch, B.; Cocke, C.L.; Voelpel, R.; Salzborn, E. Electron capture from C₆₀ by slow multiply charged ions. Phys. Rev. Lett. 1994, 72, 1439–1442; Scheier, P.; Hathiramani, D.; Arnold, W.; Huber, K.; Salzborn, E. Multiple ionization and fragmentation of negatively charged fullerene ions by electron impact. Phys. Rev. Lett. 2000, 84, 55–58; Hathiramani, D.; Aichele, K.; Arnold, W.; Huber, K.; Salzborn, E.; Scheier, P. Electron‐impact induced fragmentation of fullerene ions. Phys. Rev. Lett. 2000, 85, 3604–3607], as well as between charged fullerene ions and neutral targets [Hvelplund, P.; Andersen, L.; Haugen, H.; Lindhard, L.; Lorents, D.C.; Malhotra, R.; Rouff, R. Dynamical fragmentation of C₆₀ ions. Phys. Rev. Lett. 1992, 69, 1915–1918; Hvelplund, P.; Andersen, L.; Brink, C.; Yu, D.; Lorents, D.C.; Rouff, R. Charge transfer in collisions involving multiply charged C₆₀ molecules. Z. Phys. D 1994, 30, 323; Rohmund, F.; Campbell, E.E.B. Resonant and non‐resonant charge transfer in C₆₀ ⁺ + C₆₀ and C₇₀ ⁺ and C₆₀ collisions. J. Phys. B: At. Mol. Opt. Phys. 1997, 30, 5293–5304; Shen, H.; Hvelplund, P.; Mathur, D.; Barany, A.; Cederquist, H.; Selberg, N.; Lorents, D.C. Fullerene–fullerene collisions: fragmentation and electron capture. Phys. Rev. A 1995, 52, 3847–3851], the fundamental processes of electron transfer, ionization, and fragmentation have been studied extensively. Here we report on our experiments on electron transfer in the collision systems C₆₀ ⁺ + ³He²⁺ → C₆₀ ²⁺ + ³He⁺ and C₆₀ ⁺ + C₆₀ ²⁺ → C₆₀ ²⁺ + C₆₀ ⁺. For the latter system we also report on an upper level for the fragmentation probability.     

Flexible Janus nanofiber to acquire tuned and enhanced simultaneous magnetism-luminescence bifunctionality

A novel nanostructure of [CoFe₂O₄/PVP]//[YAG:7 % Tb³⁺/PVP] magnetic-luminescent bifunctional Janus nanofibers has been successfully fabricated via electrospinning technology using a homemade parallel spinneret. Electrospun YAG:7 % Tb³⁺ luminescent nanofibers and CoFe₂O₄ magnetic nanofibers were respectively incorporated into polyvinyl pyrrolidone (PVP) matrix and electrospun into Janus nanofibers with CoFe₂O₄ magnetic nanofibers/PVP as one strand nanofiber and YAG:7 % Tb³⁺ luminescent nanofibers/PVP as another strand nanofiber. [CoFe₂O₄/PVP]//[YAG:7 % Tb³⁺/PVP] magnetic-luminescent bifunctional Janus nanofibers possess superior magnetic and luminescent properties due to their peculiar nanostructure, and the luminescent characteristics and saturation magnetizations of the Janus nanofibers can be tuned by adding various amounts of YAG:7 % Tb³⁺ luminescent nanofibers and CoFe₂O₄ magnetic nanofibers. Compared with CoFe₂O₄/YAG:7 % Tb³⁺/PVP composite nanofibers, the magnetic-luminescent bifunctional Janus nanofibers provide higher performances due to isolating YAG:7 %Tb³⁺ luminescent nanofibers from CoFe₂O₄ magnetic nanofibers. Formation mechanism of [CoFe₂O₄/PVP]//[YAG:7 % Tb³⁺/PVP] Janus nanofibers is also presented. The design conception and construction technology are of universal significance to fabricate other bifunctional Janus nanofibers.     

C60 and C70 pressure-and-temperature transformations into fullerene-related forms

A two-stage pressure-and-temperature treatment of the C₆₀ and C₇₀ fullerites was carried out. C₆₀ and C₇₀ molecules collapsed at the first-stage hot-isostatic-pressing (HIP; 220 MPa, argon) and transformed into some fullerene-related form in the 900–1750°C temperature range. These materials were used at the second stage of the high-pressure-high-temperature (HPHT; 7.7 GPa/1400°C) treatment to produce the bulk samples that had: a specific weight of about 2.0 g/cm³, 40/110 GPa Young modulus, 6.0/12.5 GPa, and elastic recovery above 81%. Transformations under the treatments were investigated with the X-ray and transmission electron microscopy techniques. The mechanism of the pressure-and-temperature transformations is discussed.     

Singlet‐Triplet Transition in the C60 2− Dianion

Abstract

The C₆₀ complexes with decamethylcobaltocene: (Cp*₂Co)₂C₆₀(C₆H₄Cl₂, C₆H₅CN)₂ (1) and [K · (18‐crown‐6)]₂ · C₆₀ · (DMF)₄ (2) have been obtained as single crystals by the diffusion method. The IR‐ and UV‐VIS‐NIR‐spectra justify the formation of the C₆₀ ^2? dianions in these salts. EPR measurements show that the low temperature signals of 1 in the 4–140 K range and 2 in the 4–60 K range have intensity corresponding only to 0.4% and 3.5% from total C₆₀. Because of this, most of the complexes are EPR silent, and, consequently, C₆₀ ^2? has a diamagnetic singlet (S = 0) state in these temperature ranges. The appearance of a broad EPR signal in the spectum of 1 above 140 K and 2 above ～60 K is assigned to a thermal population of a close lying excited triplet (S = 1) state. The singlet–triplet energy gap for C₆₀ ^2? in solid 1 and 2 was estimated to be 730 ± 10 and 300 ± 10 cm^?1.     

Lithium ion conducting solid polymer blend electrolyte based on bio-degradable polymers

Lithium ion conducting polymer blend electrolyte films based on poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) with different Mwt% of lithium nitrate (LiNO₃) salt, using a solution cast technique, have been prepared. The polymer blend electrolyte has been characterized by XRD, FTIR, DSC and impedance analyses. The XRD study reveals the amorphous nature of the polymer electrolyte. The FTIR study confirms the complex formation between the polymer and salt. The shifts in T _g values of 70 PVA–30 PVP blend and 70 PVA–30 PVP with different Mwt% of LiNO₃ electrolytes shown by DSC thermograms indicate an interaction between the polymer and the salt. The dependence of T _g and conductivity upon salt concentration has been discussed. The ion conductivity of the prepared polymer electrolyte has been found by a.c. impedance spectroscopic analysis. The PVA–PVP blend system with a composition of 70 wt% PVA: 30 wt% PVP exhibits the highest conductivity of 1·58 × 10^???6 Scm^???1 at room temperature. Polymer samples of 70 wt% PVA–30 wt% PVP blend with different molecular weight percentage of lithium nitrate with DMSO as solvent have been prepared and studied. High conductivity of 6·828 × 10^???4 Scm^???1 has been observed for the composition of 70 PVA:30 PVP:25 Mwt% of LiNO₃ with low activation energy 0·2673 eV. The conductivity is found to increase with increase in temperature. The temperature dependent conductivity of the polymer electrolyte follows the Arrhenius relationship which shows hopping of ions in the polymer matrix. The relaxation parameters (ω) and (τ) of the complexes have been calculated by using loss tangent spectra. The mechanical properties of polymer blend electrolyte such as tensile strength, elongation and degree of swelling have been measured and the results are presented.     

Luminescent electrospun composite nanofibers of [Eu(TFI)3(Phen)]·CHCl3/polyvinylpyrrolidone

The luminescent europium complex [Eu(TFI)₃(Phen)]·CHCl₃ (TFI = 2-(2,2,2-trifluoroethyl)-1-indone, Phen = 1,10-phenanthroline) was incorporated into poly(vinylpyrrolidone) (PVP) matrixes and electrospun into nanofibers. The effect of [Eu(TFI)₃(Phen)]·CHCl₃ on the morphology and luminescence of composite nanofibers has been studied. FT-IR and TGA analyses of the composite nanofibers have been conducted and discussed. Further, the Judd–Ofelt theory is employed to study the effect of the dispersion of [Eu(TFI)₃(Phen)]·CHCl₃ and the interactions between the [Eu(TFI)₃(Phen)]·CHCl₃ molecules and neighboring chain segments of PVP. The results suggest that PVP led to the increased polarization degree of Eu³⁺ ions and significantly enhanced the electronic dipole-allowed transitions of Eu³⁺ ions, resulting in the enhancement of luminescent efficiency.     

Parallel spinnerets electrospinning construct and properties of electrical-luminescent bifunctional bistrand-aligned nanobundles

A structure of electrical-luminescent bifunctional bistrand-aligned nanobundles has been successfully fabricated by specially designed parallel spinnerets electrospinning technology. Eu(BA)₃phen (BA = benzoic acid, phen = 1,10-phenanthroline) and polyaniline (PANI) were respectively incorporated into polyvinyl pyrrolidone (PVP) and electrospun into bistrand-aligned nanobundles with PANI/PVP as one strand nanofiber and Eu(BA)₃phen/PVP as another strand nanofiber. The morphologies and properties of the final products were investigated in detail by scanning electron microscopy, transmission electron microscopy, fluorescence spectroscopy, Hall effect measurement system, and UV–Vis-NIR spectrophotometer. It is found that the as-prepared samples exhibit the nanostructures of bistrand-aligned nanobundles. The mean diameter for individual nanofiber of the bistrand-aligned nanobundles is 180 nm. The [PANI/PVP]//[Eu(BA)₃phen/PVP] bistrand-aligned nanobundles possess excellent electrical conduction and luminescent properties. Fluorescence emission peaks of Eu³⁺ are observed in the [PANI/PVP]//[Eu(BA)₃phen/PVP] electrical-luminescent bifunctional bistrand-aligned nanobundles and assigned to ⁵D₀ → ⁷F₀ (581 nm), ⁵D₀ → ⁷F₁ (592 nm), ⁵D₀ → ⁷F₂ (615 nm) energy levels transitions of Eu³⁺ ions, and the ⁵D₀ → ⁷F₂ hypersensitive transition at 615 nm is the predominant emission peak. The electrical conductivity reaches up to the order of 10^?3 S/cm. The electrical conductivity and luminescent intensity of the bistrand-aligned nanobundles can be tunable by adding various amounts of PANI and rare earth complex. The novel [PANI/PVP]//[Eu(BA)₃phen/PVP] electrical-luminescent bifunctional bistrand-aligned nanobundles have potential applications in display devices and nanomechanics, etc. owing to their excellent electrical conduction and fluorescence.     

Light Scattering Study of Aqueous Poly(Vinyl)pyrrolidone–Fullerene C70 Solutions

Abstract

It was shown by static and dynamic light scattering that poly(vinyl)pyrrolidone (PVP) molecules form large intermolecular complexes (clusters) with C₇₀ in aqueous solutions. The molecular weights and dimensions of PVP–C₇₀ clusters increase both with the increase of fullerene content and the molecular weight of the matrix PVP. However, two different diffusion coefficients were detected by dynamic light scattering. The slow mode was explained as diffusion of large PVP–C₇₀ clusters. The fast mode represents free PVP molecules in solution. Dimensions of clusters revealed in aqueous PVP–C₇₀ solutions are less than that for PVP–C₆₀ by factor of 2.5–3.     

Effect of dimethyl borate composition on the performance of boron doped ZnO dye-sensitized solar cell (DSSC)

Effect of dimethyl borate (C₃H₉BO₃) composition on the structure, morphology, thickness, elemental composition, optical absorption, photoluminescence of ZnO nanotubes and the performance of the DSSC has been studied. It was found that the structure, diameter, thickness, elemental composition, optical absorption and morphology of ZnO nanostructure are significantly influenced by the composition of dimethyl borate. The diameter and thickness of ZnO nanotubes decrease with the increase in the composition of C₃H₉BO₃. The photoluminescence increases with the composition of C₃H₉BO₃. The DSSC utilizing ZnO nanotubes synthesized at 1 wt% C₃H₉BO₃ yields the J _SC and η of 1.9 mA cm^?2 and 0.222 %, respectively.     

High refractive index films of ZnS/PVP nanocomposite by in situ thermolysis

A simple and rapid process for deposition of high refractive index films of ZnS/PVP nanocomposite (NC) is described. Precursor films are dip-coated on glass/quartz substrates from methanolic solution of polyvinylpyrrolidone (PVP) containing Zn⁺²–thiourea (TU) complex. ZnS/PVP nanocomposite films are produced by heating the solid precursor at 200°C for 10 min in air. Heat treatment converts the Zn⁺²–TU complex to ZnS by thermolysis in situ PVP. The transmission spectra of the films (typically 700 nm thickness) in the wavelength range of 200–1000 nm showed an absorption edge near 300 nm due to ZnS nanoparticles and high transmission of 97% beyond 400 nm. ZnS nanoparticles are uniformly dispersed in PVP matrix having sizes of about 3–4 nm. For ZnS loading of 45% by weight, the refractive index of ZnS/PVP is 1.65 which is in between that of PVP (1.48) and ZnS (2.36). Fourier Transform Infrared (FTIR) spectroscopy of the composite showed that there is a strong interaction between ZnS nanocrystals and PVP. The root mean square (RMS) roughness of the films is about 3 nm as determined by atomic force microscope (AFM).     

Crystal and Molecular Structure of a New Complex of [60]Fullerene, 2(C60)·2(TMTSF)·(C6H6)

Abstract

A new molecular complex of [60]fullerene with composition 2(C₆₀)·2(TMTSF)·(C₆H₆) was synthesized. The structure and composition of the complex were found by an x-ray study. Crystal data: 2(C₆₀)2(C₁₀H₁₂Se₄)(C₆H₆), M = 2415.4, monoclinic, a = 19.388(4), b = 13.410(2), c = 32.467(6) A, β = 92.71(2)°, V = 8432(3) [Adot]³, space group P2₁/n, Z = 4, d_calc = 1.903 g/cm³, R = 0.0606. The crystal structure was shown to be layered with the alternating layers of three types. Two of them have the same composition (C₆₀, TMTSF) but different interorientation of molecules in a layer and different number of shortened contacts C…C and C…Se. The third layer consists of benzene molecules. The energy of intermolecular interactions C₆₀…. TMTSF was estimated by ab initio calculations. The TMTSF molecule has a “boat” conformation.     

A new strategy to assemble enhanced magnetic–photoluminescent bifunction into a flexible nanofiber

A new type of magnetic–photoluminescent bifunctional [Fe₃O₄@Y₂O₃:Eu³⁺]/polyvinyl pyrrolidone (PVP) flexible composite nanofibers were successfully prepared via electrospinning through dispersing Fe₃O₄@Y₂O₃:Eu³⁺ core–shell structured nanoparticles (NPs) into the PVP matrix. The structure, morphology, and properties of the flexible composite nanofibers were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), and fluorescence spectroscopy. The diameter of [Fe₃O₄@Y₂O₃:Eu³⁺]/PVP nanofibers is ca. 128.57 ± 36.72 nm. Fluorescence emission peaks of Eu³⁺ in both Fe₃O₄@Y₂O₃:Eu³⁺ NPs and [Fe₃O₄@Y₂O₃:Eu³⁺]/PVP nanofibers are observed and assigned to the energy levels transitions of ⁵D₀ → ⁷F₀ (580 nm), ⁵D₀ → ⁷F₁ (533, 586, 592, 599 nm), ⁵D₀ → ⁷F₂ (612 nm), and ⁵D₀ → ⁷F₃ (629 nm) of Eu³⁺ ions. Compared with Fe₃O₄/Y₂O₃:Eu³⁺/PVP nanofibers, [Fe₃O₄@Y₂O₃:Eu³⁺]/PVP nanofibers possess much stronger luminescence. The as-prepared [Fe₃O₄@Y₂O₃:Eu³⁺]/PVP flexible composite nanofibers simultaneously exhibit excellent magnetism and photoluminescent performance. The intensities of magnetism and luminescence of the composite nanofibers can be simultaneously tuned by adjusting the amount of Fe₃O₄@Y₂O₃:Eu³⁺ NPs introduced into the nanofibers. The high performance [Fe₃O₄@Y₂O₃:Eu³⁺]/PVP flexible composite nanofibers have potential applications in bioimaging, cell separation, and future nanomechanics.     

Transformation of the electronic structure of fullerene C60 caused by complex formation in N-methylpyrrolidone solutions

Evolution of the electronic absorption and photoluminescence spectra of the fullerene C₆₀ solutions with various concentrations in a polar solvent (N-methylpyrrolidone) was studied. Comparison with the electrooptical properties of these solutions shows that a slow (associative) fullerene-solvent interaction mechanism is operative at large (nearly saturating) concentrations (1×10^?3 g/cm³), whereas the solutions of relatively low concentration (less than 5×10^?4 g/cm³) exhibit fast complex formation between fullerene and the solvent molecules. The latter interaction significantly changes the electronic structure of fullerene.     

Application of poly(3,4-ethylenedioxythiophene):polystyrenesulfonate in polymer heterojunction solar cells

In this study, p-type semiconducting polymer of acid, poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), has been employed as a hole-transporting electrode to fabricate organic polymer heterojunction photovoltaic cells. The results showed that the resultant poly(3-hexylthiophene): C₆₀ derivatives [6]-phenyl-C₆₁-butyric acid methyl ester (P3HT:PCBM)/PEDOT:PSS can significantly expand the light absorption range which was expected to enhance the sunlight excitation. The influences of annealing conditions and barrier layer on the photoelectric performances were investigated in detail, giving an optimized synthesis conditions: annealed temperature was at 120 °C for 90 min, the thickness of PEDOT:PSS film was approximately 3–4 μm, and the ratio of PCBM and P3HT was 1:2. The blended heterojunction consisting of PCBM and P3HT was used as charge carrier-transferring medium to replace I₃ ^?/I^? redox electrolyte, showing a short-circuit current of 4.30 mA cm^?2, an open-circuit voltage of 0.83 V, and a light-to-electric energy conversion efficiency of 2.37 % under a simulated solar light irradiation of 100 mW cm^?2. In addition, a solid-state polymer heterojunction photovoltaic cells with a short-circuit current of 3.59 mA cm^?2, an open-circuit voltage of 0.80 V, and a light-to-electric energy conversion efficiency of 1.9 % was successfully fabricated by simplifying the process.