A study on the structure and electrical properties of the fourth carbon allotrope: carbyne

The acetylenic and cumulenic forms of carbyne (α and β-carbyne, respectively) have been obtained simultaneously by oxidative coupling of dicopper acetylide under Glaser conditions. Carbynes having copper atoms, or phenyl groups, at the ends of the chains were successfully synthesized. At room temperature these end-groups confer an indefinite stability to this allotrope, whereas at high temperature in vacuo β-carbyne is transformed to α-carbyne, which is thermodynamically more stable. Carbyne chemical structure was studied and confirmed by FTIR spectroscopy, electronic spectroscopy, and X-ray diffraction. The chemical reactivity of carbyne was checked versus chlorine in the presence of UV light and dinitrogen tetroxide. The specific conductivity of undoped carbyne obtained by Glaser synthesis was found to be in the range 2·11×10^-6–1·41×10^-6Scm^-1, just one order of magnitude lower than the conductivity of trans-polyacetylene. Polyeneyne or ‘Straus carbyne’ was synthesized via the Straus reaction and its structure was studied by FTIR and electronic spectroscopy. ©1997 SCI     

Structural changes and crystallization kinetics of polylactide under CO2 investigated using high‐pressure Fourier transform infrared spectroscopy

The structural changes and crystallization kinetics of polylactide (PLA) during cold crystallization under CO₂ at 80 °C were studied using in situ high‐pressure Fourier transform infrared (FTIR) spectroscopy. The FTIR spectra show that PLA can crystallize under air and CO₂, and some differences are observed. In the second‐derivative spectra, the 1220 cm^?1 band is only found for PLA crystallized under CO₂, and the tt conformer of PLA crystallized under CO₂ is located at 1749 cm^?1, while that of PLA crystallized under air is located at 1751 cm^?1. From wide‐angle X‐ray diffraction, only the α′‐crystal is observed when PLA is crystallized under air, whereas the α‐crystal appears when crystallized under CO₂. The crystalline‐sensitive bands at 921 and 1458 cm^?1 were used to analyze the crystallization kinetics of PLA. When PLA crystallizes under air, the 1458 cm^?1 band changes faster than the 921 cm^?1 one; when it crystallizes under CO₂, the result reverses. This suggests that CO₂ hinders interchain interactions while promoting the helix conformation. © 2015 Society of Chemical Industry     

Chelation of chitosan derivatives with zinc ions. II. Association complexes of Zn2+ onto O,N‐carboxymethyl chitosan

The chelation of zinc ions onto O,N‐carboxymethyl chitosan (ONCMCh) was characterized using a Fourier transform infrared (FTIR) spectrophotometer and a scanning electron microscope (SEM). From the FTIR spectra, little change in the absorption intensities and frequencies at 3300–3600 cm⁻¹ of Zn²⁺ ONCMCh chelated specimens suggested that  OH and  NH₂ groups were not participating in the chelation reaction. The absence of absorption bands at 1755–1700 cm⁻¹ suggested that the carboxyl group CO was not ionized, and the ionized CO bands were observed at 1400–1600 cm⁻¹ for chelated specimens. Thus, the chelation sites took place at the carboxyl group rather than at the  OH and NH₂ groups. It also confirmed that water‐insoluble chelates, which were formed through the Zn O and Zn N bonds, presented a tetrahedral structure. The water‐soluble complexes where zinc ions connected with oxygen of CO and water molecules were only due to electron attraction. Formation of different microstructures on the surfaces, as revealed by SEM, provided evidence to distinguish different chelating mechanisms between water‐soluble and water‐insoluble complexes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1476–1485, 2001     

Raman and surface-enhanced Raman scattering of a series of size-separated polyynes

Solutions of hydrogen-capped polyynes were prepared by laser ablation of graphite powder in n-hexane and subjected to size separation by high-performance liquid chromatography. Solutions of size-selected polyynes C_nH₂ (n = 8–16) were investigated by normal Raman (NR) and surface-enhanced Raman scattering (SERS) spectroscopy. A main band appearing in the 2000–2200 cm⁻¹ region of the NR spectra showed a systematic downward shift as the chain length increased. The observed NR bands were assigned to Raman-active CC stretching vibrational modes by comparison with calculations based on density functional theory. Raman bands observed in SERS spectra were very broad and located at frequencies lower than the NR bands. A systematic band shift with increasing chain length was also observed for one of the bands. This band was thus assigned to a counterpart of the strong band in the NR spectra. These results made it possible to assign the origins of previously reported SERS bands of mixed polyyne solutions.     

Photoconductivity and photovoltaic properties of polyaniline immobilized onto metallurgical porous silicon powder

Photoactive composites comprising polyaniline and metallurgical silicon powder were prepared by an in situ two‐step procedure (pSi‐PANI). Their structures were elucidated by electronic and infrared spectroscopy and powder X‐ray diffraction (P‐XRD) techniques. The P‐XRD revealed that the acid‐doped green composites (pSi‐PANI·HCl and pSi‐PANI·HF) acquire a two‐dimensional crystalline array structure featuring nanosheet morphology. The photoconductivity and photovoltaic (PV) properties of these composites were examined as flexible microscopic films of finely dispersed composites in a dry linseed oil matrix sandwiched between two aluminium electrodes, [Al_perforated/pSi‐PANI/Al_plate]. The hybrid composites display a thermal voltage in the dark but develop a photocurrent under weak illumination (incandescent lamp, 75.4 µW cm^–2). These green composites exhibit enhanced power conversion efficiency (J_sc = 16.7–34.0 μA cm^–2, V_oc = 0.86–1.21 V, η = 5.2%–11.4%) compared with their undoped blue analogs (J_sc = 1.3–6.1 μA cm^–2, V_oc = 0.18–1.02 V, η = 0.1%–2.1%). The pSi‐PANI·HCl composite is a promising candidate for the development of a low‐cost, easily processed, flexible PV system that can be scaled up for large‐area indoor applications. © 2012 Society of Chemical Industry     

Synthesis and characterization of polypyrrole using TiO2 nanotube@poly(sodium styrene sulfonate) as dopant and template

A polypyrrole (PPy) using TiO₂ nanotube@poly(sodium styrene sulfonate) (TiO₂@PSS) as dopant and template was synthesized by chemical oxidation polymerization. The template TiO₂@PSS consisting of a TiO₂ nanotube core and PSS on the surface was prepared by a “grafting from” approach. PPy on the layer of TiO₂@PSS (TiO₂@PSS/PPy) was characterized by transmission electron microscopy, scanning electron microscopy, X‐ray photoelectron spectroscopy (XPS), Fourier‐transform infrared spectrometry (FTIR), Raman spectroscopic analysis, UV‐visible (UV‐vis) spectroscopy, thermo gravimetric analysis, and electrical conductivity analysis. Results showed that TiO₂@PSS/PPy was successfully fabricated. The electrical conductivity of the TiO₂@PSS/PPy nanocomposites at room temperature was 11.6 S cm⁻¹, which was higher than that of the PPy (4.2 S cm⁻¹). This result was consistent with those based on FTIR, UV‐vis spectroscopy, and XPS analyses. The nanocomposites have nanoparticle size and controllable morphology and thus potential applications in photoelectrochemical devices, photocatalytic devices, conductive inks, electronic printing sensors, and electrodes. POLYM. COMPOS., 37:462–467, 2016. © 2014 Society of Plastics Engineers     

Carbonaceous materials from end-capped alkynes

A series of terminally protected alkyne derivatives iPr₃Si-(CC)_n-Si iPr₃, n=2, 3, 4, 6 was prepared by the Hay oxidative coupling. The longest oligoyne chain was in 1,12-bis-(triisopropylsilyl)-1,3,5,7,9,11-dodecahexayne (V), that is a new substance exhibiting reasonable stability even in the solid state (m.p. 112.5°C). The prepared oligoynes were studied by UV-Vis, Raman, FTIR, ¹³C-NMR and mass spectroscopy. The corresponding de-protected free alkynes polymerized spontaneously in n-hexane solution at room or sub-room temperatures towards new carbonaceous materials, which were characterized analytically and spectroscopically.     

An effective method to identify the type and content of α‐olefin in polyolefine copolymer by Fourier Transform Infrared–Differential Scanning Calorimetry

A new method for identification of ethylene/α‐olefin copolymer was established by Fourier Transform Infared (FTIR)–Differential Scanning Calorimetery (DSC) in this article. DSC and FTIR spectroscopy techniques were used to analysis the type and content of α‐olefin in polyolefine copolymer. FTIR was available to identify the structures of polyethylene and copolymers of ethylene with different α‐olefins. The type of polyethylene can be determined by the peak position of 1378 and 1369 cm^?1. According to the peak location of 770, 784, and 895 cm^?1, the type of α‐olefin can also be determined. DSC method was used to decide the position of melting peaks. The quantitative investigation of the content of α‐olefin in polyethylene was calculated by the formula: ?ln(CH₂ mol fraction) = ?0.331+135.5/T_m. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of hydrogen‐bonding in the development of high‐affinity metal ion complexants: Polymer‐bound phosphorylated cyclodextrin

In a series of phosphorylated polyols bound to a polystyrene support, the position of the FTIR band assigned to hydrogen bonding between the  OH and phosphoryl oxygen correlates with the affinity of that phosphoryl oxygen for metal ions. Polymer with phosphorylated β‐cyclodextrin (pCD) ligands is now reported as a further test of this correlation. The metal ion affinity is probed with the uranyl ion. pCD is the most red‐shifted of a series of five phosphorylated polyols: the strongest polyol had been phosphorylated pentaerythritol (pPE) with a band at 873 cm⁻¹; pCD has a band at 868 cm⁻¹. Consistent with the FTIR bands, pCD has a significantly higher affinity for the uranyl ion than pPE: the percents complexed from a 10⁻⁴M uranyl solution in a background of 1.0N HNO₃, HCl, and H₂SO₄ are 94.7%, 90.5%, and 93.6%, respectively, for pCD and 68.6%, 52.1%, and 40.1%, respectively, for pPE. This further supports the hypothesis that the strong complexing ability of phosphorylated polyols is due to activation of the phosphoryl oxygen through hydrogen bonding between the PO and the  OH groups within the polyol. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Complexation of Zirconium Alkoxides with 3-Pentenoic Acid and Hydrolytic Stability of Their Products

Reactions of Zr(OPr ⁿ )₄ and Zr(OBu ⁿ )₄ with 3-pentenoic acid (PA) in 1:1 molar ratio were studied in propanol and butanol solution at room temperature by the sol–gel process. The complexations were investigated by ¹³C{¹H}, ¹H-NMR and FTIR spectroscopy. The ¹³C{¹H}, ¹H-NMR and FTIR spectra showed that PA completely reacted with Zr(OPr ⁿ )₄ and Zr(OBu ⁿ )₄. The new products were hydrolyzed by water in a ratio of 1:4 (Zr(OR ⁿ )₄/ H₂O, R = propyl, butyl). The stability of hydrolyzed products was investigated spectroscopically. After hydrolysis, it was observed that no PA was released from the complexes, [Zr(OPr ⁿ )₃(PA)] and [Zr(OBu ⁿ )₃(PA)], under the reaction conditions.     

Surface modification of bioceramics by grafting of tailored allyl phosphonic acid

Abstract

A new route to interfacial bonding between ceramic and matrix in biocomposites is identified. A tailored allyl phosphonic acid is used as a coupling agent bound to the surface of a bioceramic to form a 'grafted' calcium phosphate (CAP). The allyl phosphonic acid coupling agent is synthesised by reaction of allyl halide and trialkyl phosphite. Successful synthesis was confirmed by nuclear magnetic resonance and Fourier transform infrared spectroscopy (FTIR). The allyl phosphonic acid was incorporated onto calcium phosphate using a wet chemical coprecipitation synthesis route. The resulting 'grafted' CAP was characterised using FTIR coupled with photoacoustic sampling, and Fourier transform Raman spectroscopy (FTR). The spectroscopic data suggest an interaction between the allyl phosphonic acid and calcium phosphate resulting from observed reductions in intensity of the hydroxyl (3570 cm^?1) and phosphate ν ₃ (1030 cm^?1) peaks. The continued presence of C=C functionality on the surface of the grafted CAP was indicated by FTIR and FTR spectra (peaks at 1650 and 1635 cm^?1 respectively) and confirmed by X-ray photoelectron spectroscopy (XPS). On the basis of these results, it is concluded that grafted CAP may be used to produce a chemically bonded composite with superior mechanical properties.     

Isomerization and Decomposition of Chloromethylacetylene

The isomerization and thermal decomposition of chloromethylacetylene (CMA) has been studied with two shock tube techniques. The first experiment (Jerusalem) utilizes single-pulse shock tube methods to measure the isomerization rate of CMA to chloroallene. In addition, equilibrium constants can be estimated at ∼1200 K. The second experiment (Argonne) monitors Cl-atom formation at temperatures above ∼1150 K. Absolute yield measurements have been performed over the 1200–1700 K range and indicate that two decomposition channels contribute to CMA destruction, namely, Cl fission and HCl elimination. The results show that the branching fraction between processes is temperature dependent. Therefore, direct Cl-atom fission is accompanied by molecular elimination, undoubtedly giving HCl and one or more isomers of C₃H₂. MP2 6–31G(d,p) ab initio electronic structure calculations have been used to determine vibration frequencies and moments of inertia for three C₃H₃Cl isomers. Using these quantities, the experimental equilibrium constants required that ΔH⁰₀(CH₂Cl–C≡CH ⇌ CHCl=C=CH₂) = −;0.24 kcal mole⁻¹. A potential energy surface pertinent to the present system has been constructed, and RRKM calculations have been carried out in order to explain the isomerization rates. The isomerization data can be explained with E₀ = 52.3 kcal mole⁻¹ and 〈ΔE_down〉 = 225 cm⁻¹. Subsequent semi-empirical Troe and RRKM-Gorin modeling of the Cl atom rate data require E₀ = (67.5 ± 0.5) kcal mole⁻¹ with a 〈ΔE_down〉 = (365 ± 90) cm⁻¹. This suggests a heat of formation for propargyl radicals of (79.0 ± 2.5) kcal mole⁻¹.     

Synthesis and characterization of conducting poly(aniline‐co‐diaminodiphenylsulfone) copolymers

Polyaniline, poly(aniline‐co‐4,4′‐diaminodiphenylsulfone), and poly(4,4′‐diaminodiphenylsulfone) were synthesized by ammonium peroxydisulfate oxidation and characterized by a number of techniques, including infrared spectroscopy, ultraviolet–visible absorption spectroscopy, ¹H‐NMR, thermogravimetric analysis, and differential scanning calorimetry. These copolymers had enhanced solubility in common organic solvents in comparison with polyaniline. The conductivities of the HCl‐doped polymers ranged from 1 S cm^?1 for polyaniline to 10^?8 S cm^?1 for poly(4,4′‐diaminodiphenylsulfone). The copolymer compositions showed that block copolymers of 4,4′‐diaminodiphenylsulfone (r₁ > 1) and aniline (r₂ < 1) formed and that the reactivity of 4,4′‐diaminodiphenylsulfone was greater than that of aniline. The results were explained by the effect of the ? SO₂? group present in the polymer structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2337–2347, 2003     

Single‐stage Treatment in Selective Hydrogenation of Acetylene over CDS Type of Pd‐Ag/Al2O3 Catalyst

The (computer designed shape) CDS type of Pd‐Ag/Al₂O₃ catalyst in single‐stage reactor provides superior catalytic activity and selectivity of ethylene in comparison with those of existed two‐stage reactors packed with G‐58B catalyst under industrial operating conditions. In this research, the contents of palladium and silver of catalysts were analyzed by inductive coupling plasma (ICP). The X‐ray photoelectron spectroscopy (XPS) showed that Pd‐Ag alloy has been formed. Higher yield of ethylene may be interpreted by both geometric and electronic effect induced from silver metal. By means of Pyrolysis/GC/MS analysis of used catalysts, the components of carbonaceous deposits were found to be n‐alkenes, including n‐C8 ～ n‐C16 or n‐C18, which may result from oligomerization of acetylene.     

Study of Combustion Properties of a Solid Propellant by Highly Time‐Resolved Passive FTIR

With a time resolution of 0.125 s and a spectral resolution of 4 cm⁻¹, emission spectra of the combustion process of a solid propellant were recorded by highly time‐resolved passive FTIR. Some gaseous combustion products, such as H₂O, CO, CO₂, NO and HCl, were distinguished by the characteristic emission band of each molecule. The equation for flame temperature calculation based on the diatomic molecule emission fine structure theory was improved through judicious utilization of the spectral running number ‘m’ which makes the temperature measurement simpler and faster. Some combustion information of the solid propellant had been given including the characteristic spectral profile, the distribution of the absolute spectral energy, the distribution of the combustion flame temperature, and the concentration distributions of HCl and NO versus burning time. The results will provide theoretical and experimental bases for improving the formula and raising combustion efficiency of solid propellant, and developing the design of rocket motor, infrared guidance and antiguidance systems.     

Comparative study of corrosion inhibition by three anionic surfactants in an acidic environment

Corrosion in carbon steel units of chemical, petrochemical and oil and gas plants poses safety and economic concerns. The goal of our study is to investigate the corrosion inhibition effectiveness of an environmentally benign surfactant, namely sodium lauroyl lactylate (SLL), in comparison to sodium cocoyl glutamate (SCG) and sodium dodecyl sulfate (SDS). The corrosion of carbon steel in 1 M HCl was markedly inhibited by 0.05 and 0.1 M of the anionic surfactant SLL, as determined from weight loss over 96 h, at ambient conditions. X-ray photoelectron spectroscopy (XPS) showed that SLL adsorbed at the carbon steel surface, forming a protective film that decreased corrosion. Scanning electron microscopy (SEM) showed that carbon steel surfaces immersed in 1 M HCl for 96 h had an etched appearance without SLL, whereas they retained their smoothness with 0.1 M SLL. Electrochemical impedance spectroscopy (EIS) measurements confirmed that SLL passivated carbon steel surfaces, markedly increasing the polarization resistance R_p from ≈95 to ≈20,694 Ω cm² over a 12 h period. In contrast, without SLL, R_p decreased from ≈92 to ≈12 Ω cm². These results demonstrate for the first time that the environmentally friendly surfactant SLL is an efficient corrosion inhibitor in extreme environments such as 1 M HCl solutions. Dissimilar to SLL, SCG and SDS were not effective in inhibiting corrosion.     

One-Dimensional Coordination Polymer Assembled by Tetraaza Macrocyclic Nickel(II) Complex and trans-1,4-Cyclohexanedicarboxylate ligand

The reaction of [Ni(L)]Cl₂·2H₂O (L = 3.14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane) with trans-1,4-cyclohexanedicarboxylic acid (H₂chdc) generates a 1D coordination and 2D hydrogen-bonded polymer {[Ni(L)(chdc)₂]·2H₂O}_n (1). The polymer complex was characterized by X-ray crystallography, spectroscopy and magnetic susceptibility. Each nickel(II) ion has a distorted octahedral coordination environment with the four secondary amines of the macrocycle in which two trans carboxylate anions of the chdc²⁻ ligand have assembled around each nickel center. The electronic spectrum of 1 in the solid state exhibits a high-spin octahedral environment. The magnetic behavior of 1 reveals a weak intramolecular antiferromagnetic interaction with J values of −1.15(2) cm⁻¹.     

Improvement of the electrochemical behavior of steel surfaces using a TiN[BCN/BN]n/c-BN multilayer system

The aim of this work is to improve the electrochemical behavior of AISI 4140 steel substrates by using a TiN[BCN/BN]_n/c-BN multilayer system as a protective coating. We grew TiN[BCN/BN]_n/c-BN multilayers via reactive r.f. magnetron sputtering technique, systematically varying the length period (Λ) and the bilayer number (n), maintaining constant the total thickness of the coating and all other growth parameters. The coatings were characterized by FTIR spectroscopy that showed bands associated to h-BN bonds, and c-BN stretching vibrations centered at 1385 cm^− 1 and 1005 cm^− 1, respectively. Film composition was studied via X-ray photoelectron spectroscopy where typical signals for C1s, N1s and B1s are shown. The electrochemical properties were studied by electrochemical impedance spectroscopy and Tafel curves. In this work, the maximum corrosion resistance for the coating with (Λ) equal to 80 nm was obtained, corresponding to n = 25 bilayers. The polarization resistance and corrosion rate were around 10.1 kOhm cm² and 0.22 mm/year; these values were 83 and 15 times higher, respectively, than uncoated AISI 4140 steel substrate (0.66 kOhm cm² and 18.51 mm/year). Optical microscopy was used for surface analysis after corrosive attack. The improvement of the electrochemical behavior of the AISI 4140 coated with this TiN[BCN/BN]_n/c-BN multilayer system can be attributed to the presence of several interfaces that offer resistance to diffusion of Cl⁻ of the electrolyte toward the steel surface.     

Formation and Migration of NCO Species on Ag/SiO2 Catalyst

The adsorption of HNCO has been investigated on Ag/SiO₂ catalyst by means of FTIR spectroscopy. Adsorption of HNCO on the reduced sample at 190 K produced an absorption band at 2,170 cm⁻¹ attributed to NCO bonded to Ag. Annealing the adsorbed layer under continuous degassing, the 2,170 cm⁻¹ band gradually attenuated and at the same time a spectral feature at 2,300 cm⁻¹ due to Si–NCO developed. From these spectral changes it was inferred that NCO bonded to Ag spilt over onto silica.