Chains In Solid State Research Articles

LIPAc RF power system: design and main practical implementation issues

The Linear IFMIF (International Fusion Materials Irradiation Facility) Prototype Accelerator (LIPAc) is a 9 MeV, 125 mA, continuous wave (CW) deuteron accelerator aimed to validate the technology for the IFMIF accelerators. The construction of LIPAc, which is currently the most powerful deuteron accelerator in the world, has been carried out under the Broader Approach (BA) Agreement between EU and Japan, and it is located at Rokkasho (Japan). CIEMAT is one of the five European Institutions that has participated in the design, manufacturing and commissioning/operation of the main accelerator components, among them, the Radio Frequency Power System (RFPS). The RFPS contains all the equipment necessary to generate the required RF power to feed the LIPAc cavities. These cavities demand eighteen RF power chains at 175 MHz being distributed as follows: eight 200 kW tetrode-based chains for the Radiofrequency Quadrupole (RFQ), two 16 kW solid-state chains for the re-buncher cavities, and eight 105 kW tetrode-based chains for the Superconducting RF Linac Half-Wave Resonators. The design of the RFPS main components is presented in this paper, including the tetrode-based chains, the Solid-State Power Amplifier (SSPA) for the re-buncher cavities, the High Voltage Power Supplies (HVPSs) for the final amplifiers anodes and the RF water cooling system. Additionally, the main difficulties encountered during the first months of the RFPS commissioning and operation will be described, together with the applied improvements.

Conversion among photo-oxidative products of polypropylene in solid, liquid and gaseous states

During aging of polymers, oxidized species on macromolecular chains in solid state, volatile degradation products in liquid state and gaseous degradation products in gaseous state are often investigated separately. The conversion among these products is not especially concerned and biased results may be obtained based on the products in a single state. In this paper, photo-oxidative products of commercial polypropylene (PP) and unstabilized PP in solid, liquid and gaseous states were investigated by using Fourier transform infrared spectroscopy (FTIR), pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) and gas chromatography (GC). By comparing the formation profiles, conversion among the photo-oxidative products in three states was traced. During photo-oxidative aging, the main chains of PP were first oxidized to form carbonyl species in solid state, or fractured to form volatile alkenes as liquid. With the proceeding of aging, the oxidized main chains fractured to form small molecules, resulting in the conversion of oxidized species from solid state to liquid and gaseous states. When the aging degree was extremely high, the accumulation of liquid oxidized products was limited due to migration and condensation. Therefore, both the carbonyl index (CI) and the concentrations of volatile oxidized products were increased first and then decreased, while the concentrations of gaseous products kept increasing all along.

Synthesis and Characterization of Poly(3‐Hexylthiophene) for Organic Solar Cells

Poly(3‐hexylthiophene) (P3HT) has been successfully synthesized through McCullough route. The influence of nickel catalyst content on molar mass (Mn and Mw), dispersity (Đ), regioregularity (rr), as well as optical, thermal, and morphological properties is systematically investigated. The results evidence that polymer dispersities are narrow, Mn and rr values decrease with the augmentation of catalyst content. Polymer solution in different solvents (chloroform and dichlorobenzene) show similar optical band gaps. Solid state band gap of obtained material is lower than in solution, which confirms the reorganization of polymer chains in solid state. Both polymers show good thermal stability and their morphologies are tightly influenced by the monomer/catalyst ratio in the synthesis. Two main morphologies are obtained, for the higher molar mass P3HT it is nodule‐like, while the lower Mn presented rod form. The fore polymer combined with PCMB results in lower root mean square (RMS) indicating smoother morphology, which is more appropriate for solar cells application.

The unusual improvement of normal alkyl alcohol on solid-state cationic photopolymerization of octadecyl vinyl ether

The solid-state photopolymerization of octadecyl vinyl ether was verified occur in rotator phase, and the stability of octadecyl vinyl ether in rotator phases was explained through the study of its electrostatic surface potential. Four binary systems were constructed by mixing the octadecyl vinyl ether with four normal alcohols (the carbon numbers are 12, 14, 16 and 18). The phase behaviors and the kinetics of photopolymerization of four binary systems were studied by using differential scanning calorimeter and real-time Fourier transform infrared spectroscopy. Alcohols are usually regarded as a kind of inhibitor for cationic polymerization in liquid state. However, in rotator phase photopolymerization, the conversions of octadecyl vinyl ether that mixed with octadecyl alcohol (83%) or hexadecyl alcohol (81%) were higher than that of pure octadecyl vinyl ether (47%). This phenomenon was explained from the aspect of two-dimensional solid-state chain propagation.

Synthesis and characterization of novel polyhalogenaromatic polyimide material for electro-optic applications

New highly fluorinated aromatic polyimide based on 4-chloro-2,5,6-trifluoro-1,3-phenylenediamine and 2,2-bis(3′,4′-dicarboxyphenyl)hexafluoropropane dianhydride was prepared by the two methods condensation in a solution followed by a high-temperature solid-state chain extension and one-pot high temperature polycondensation in a benzoic acid melt. The polyimide is soluble in polar amide- and ketone-type solvents, has good thermal stability and a high glass transition temperature. The polyimide films exhibit a low cut-off wavelength and excellent transparency in the UV-vis-near IR range. Low molecular weight prepolymer, formed by the solution condensation, was used to obtain the guest-host electro-optic polymer having a high glass transition temperature. The prepolymer layer doped with azochromophore DR1 (25wt%) was subjected to a combined poling+curing procedure upon a two-stepped heating in a corona discharge field. Nonlinear optical coefficient d33 of the prepared chromophore-doped highly halogenated polyimide film measured by the Maker fringes method is 70pm/V at the fundamental wavelength of 1064nm and remains stable up to 85°C.

Synthesis of Dipyridyl Ketone Isonicotinoyl Hydrazone Copper(II) Complex: Structure, Anticancer Activity and Anticancer Mechanism.

In an effort to better understand the biological efficacy of the tridentate aroyl hydrazone Cu(II) complexes, the Cu(II) complex of di-2-pyridyl ketone isonicotinoyl hydrazone ligand (HL), {[Cu(L)(H2O)]·H2O·NO3}n (C1) was synthesized and characterized. Single crystal X-ray study reveals that complex C1 forms 1D zigzag chains in solid state. In water, the hydrolysis of the 1D zigzag chains was observed, and finally formation of monomeric species. In vitro studies revealed that complex C1 showed significantly more anticancer activity than the ligand alone. Investigation of the anticancer mechanisms of C1, confirmed that the Cu(II) complex exhibit a strong capacity to promote productions of reactive oxygen species (ROS), leading to caspase-dependent apoptotic cell death.

Ethylene/1‐heptene copolymers as interesting alternatives to 1‐octene‐based LLDPE: Molecular structure and physical properties

ABSTRACTClassical linear low density polyethylenes (LLDPEs) are copolymers of ethylene and 1‐octene or 1‐hexene, respectively. In the past, other 1‐olefins have been tested as comonomers but the resulting LLDPEs were never commercialized as large scale products. The present study focuses on the use of 1‐heptene as an interesting comonomer for the synthesis of LLDPE. For a comparison of the molecular structure and the physical properties of 1‐heptene‐ and 1‐octene‐based LLDPEs, five Ziegler–Natta LLDPEs of varying comonomer contents based on 1‐heptene and 1‐octene, respectively, were acquired and analysed using advanced methods. The comonomer contents of the resins were between 0.35 and 6.4 mol %. Crystallization‐based techniques revealed similar bimodal distributions that are due to the formation of copolymer and polyethylene homopolymer fractions. The compositional distribution of the copolymers was studied by high‐temperature (HT) HPLC and HT‐2D‐LC. The analytical results indicate similar chemical heterogeneities and molar mass distributions of the two sets of LLDPE up to a comonomer content of 3 mol %. Similar to the molecular structure, the physical properties of the materials are quite similar. At comonomer contents of ≥3 mol % differences between the two sets of samples are seen that are attributed to differences in the abilities of 1‐heptene and 1‐octene in disrupting the crystal arrangements of the polymer chains in solid state. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 962–975

Atomistic Monte Carlo and molecular dynamics simulation of the bulk phase self-assembly of semifluorinated alkanes

Results are presented for the conformational, thermodynamic, structural and solid-state chain organization properties of the semifluorinated alkane F(CF2)12(CH2)12H (termed perfluorododecyldodecane and abbreviated as F12H12) from detailed, atomistic-level Molecular Dynamics and Monte Carlo simulations in the isothermal–isobaric ensemble using large simulation cells containing up to 144,000 atomistic units. To cope with the large requirements in CPU time accompanying the use of super-cells in our simulations, we identified the Monte Carlo subroutines with the largest demand in computational resources and took advantage of parallelization by multithreading on NVIDIA graphics processing units (GPUs) to improve code performance by almost one order of magnitude. Consistent simulation results for the most important properties of the system have been obtained from the two methods, especially at the higher temperatures where their predictions for the density, average square chain-end-to-end distance and dihedral angle distributions are indistinguishable (practically identical). Driven by experimental data that provide evidence for two first-order phase transitions in F12H12, we have further investigated its bulk-phase assembly by carrying out gradual cooling runs from an initial configuration of randomly distributed chains. For both methods, the study of the average-squared end-to-end molecular distance indicates that F12H12 molecules prefer to be aligned in ordered zones (lamellae), whereas the dihedral distributions exhibit a favorable trans state with decreasing temperature and/or increasing pressure, verifying the tendency of perfluorododecyldodecane to undergo a structural transition at these conditions. Our simulations support a spontaneous transition of F12H12 from an isotropic phase to a smectic-like phase at a low enough temperature (close to T=315K based on cooling experiments), at a pressure P=100atm. Intermolecular pair distribution functions and atomistic configurational snapshots show that the simulated smectic phase consists of bilayer lamellae with a variety of directions, involving tilted and non-interdigitated chains. Experimentally, two solid phases are proposed for F12H12: a high-temperature one consisting of monolayer lamellae and a low temperature one consisting of bilayer lamellae with interdigitated hydrocarbon and fluorocarbon blocks. Despite that our simulations cannot unambiguously predict a second (solid-solid) phase transition, they provide convincing evidence for the co-existence of many ordered lamellae in F12H12 below its melting point Tm both in monolayer and bilayer arrangements, with the relative population of bilayer ones increasing with decreasing temperature.

Linear Coordination Polymers Assembled from Dinuclear Cu(I) Units: Interchain π–π and CH–π Interactions in Controlling Alignments of Polymeric Chains in Solid State

An axial substitution of the coordinated acetonitrile molecules in dinuclear Cu(I) compound, [Cu2(μ-PhPPy2)2(CH3CN)2](ClO4)2 (1) (PhPPy2 = bis(2-pyridyl)phenylphosphine) by various dicarboxylates (isophthalate, terephthalate and naphthalene-2,6-dicarboxylate) led to a class of new linear coordination polymers, {[Cu2(μ-PhPPy2)2](μ-1,3-C6H4(CO2)2)}∞ (2), {[Cu2(μ-PhPPy2)2](μ-1,4-C6H4(CO2)2)}∞ (3) and {[Cu2(μ-PhPPy2)2](μ-2,6-C12H6(CO2)2)}∞ (4). X-ray crystallographic studies reveals that all the polymers adopt almost linear structures, where the dicarboxylate groups connect dinuclear Cu(I) units as linkers. In 2 and 4, polymeric chains are parallel to each other. However the chains in 3 are arranged layer by layer, where polymeric chains are parallel in one layer, but chains in the neighboring layers are aligned with the angle (42°). The detailed structural analyses demonstrate that in solid state, the polymeric chains display different orientations which are controlled by interchain π–π and CH–π interactions. In solid state, all the coordination polymers are highly emissive at room temperature, which exhibit phosphorescence characteristics and are assigned as metal to ligand charge transfer.

Determination of spatial characteristics of the chain reaction wave in silver azide

The paper presents the methodology and results of determination of the spatiotemporal characteristics of the solid-state chain reaction wave in silver azide, initiated by a neodymium laser pulsed. The wave’s leading front width at half maximum is l1 = (110 ± 10) μm, the wave’s rear front width at half maximum is l2 = (120 ± 20) μm. The spatiotemporal parameters of the reaction wave in silver azide whiskers are calculated using a phenomenological model of the process previously proposed by the authors. It is shown that the calculated values of the velocity and the wave front width are consistent with the available experimental data.

Chain Conformational Study on Underwater Silk Proteins from Caddisfly, <i>Stenopsyche marmorata - </i>Implication of a Fiber-Forming Mechanism

Larval silk/cement proteins from a caddisfly, Stenopsyche marmorata, were isolated as a protein mixture of Smsp-1, 2, 3 and 4. Smsp-1 is a giant phosphorylated protein, which occupies ca. 45%-mass of the silk gland content, and composed of a long-range periodic amino acid sequences, involving 8 kinds of characteristic segments. The silk protein film was prepared and drawn in water up to 9-folds of the initial axis length, then the drawn film was subjected to polarized FT-IR and WAXD. The results implied that the Smsp-1 backbone adopts two different conformations, one of which was the β-turn-like conformers. The molecular mechanic studies were separately performed to evaluate the solid-state chain structures of the hydrophobic/Pro-rich segments 3 and 4, which are enriched in the primary sequence of Smsp-1, and the results were coincident with those from the vibration spectra and WAXD. The molecular dynamic (MD) studies were also carried out in order to estimate their preferred chain conformations in a solution state. The MD trajectory suggests that the segments 3 and 4 tend to adopt a turn-like conformation, which is a potential precursor of the β-turn-like conformers. In conclusion, the underwater silk proteins have a fiber-forming mechanism, which is substantially different from a silkworm, Bombyx mori.

Effect of the metal⋯metal interactions on the absorption properties of Pt(II) and Pd(II) complexes of glyoxilic acid oxime in solution and solid state: Theoretical and experimental study

Abstract The electronic structures and vertical excitation energies of square-planar complexes of Pt(II) and Pd(II) with glyoxilic acid oxime (H2GAO) (cis-K[Pt/Pd(GAO)(HGAO)]) were investigated in gas phase, aqueous solution and solid state by combination of DFT/TD-DFT methods, experimental UV–vis measurement in solution and diffuse UV–vis study in solid state. The solid-state chain structures were simulated by means of dimer and trimer clusters modeling. The absorption properties of the complexes predicted for gas phase are slightly changed by the solvent and small bathochromic band shifts are found. The formation of chain structure of Pt(II) and Pd(II) complexes is discussed in relation with M⋯M dz2 orbitals interaction. According to the calculations complex aggregation due to M⋯M interactions occurs even in concentrate aqueous solution of Pt(II) complex producing change in the complex color: from yellow to orange-red. Upon aggregation the dz2 orbital interactions increase and the occupied MO involved in the first singlet excitation destabilizes due to the antibonding combination of the Pt/Pd dz2 contributions. As a result, the transition energies decrease producing bathochromic shift of the MLCT bands. For the Pt(II) complex the destabilization of HOMO is larger and produces larger bathochromic shift of the low-lying band (140 nm) as compared to that observed for the Pd(II) complex (90 nm). The larger bathochromic shift for the Pt(II) complex leads to absorption at ∼500 nm and color change from yellow (in diluted solution) to red for the crystalline Pt(II) complex. For Pd(II) trimer complex the low-lying excitation of MLCT character is below 500 nm in keeping with the yellow complex in the solid as it is in solution. It is established that the M⋯M orbital interaction strength is determined mainly by the M⋯M distances, the A(M⋯M⋯M) angle and the decisive role of the sum of VDW radii.

Detection and investigation of oscillations of the rate of radiation-induced solid-state chain reactions at low temperatures

The data on the detection and investigation of rate oscillations of radiation-induced (60Co γ-radiation) cryochemical solid-state chain reactions are reviewed. Self oscillation regimes were observed for various reactions (ethylene hydrobromination, polymerization, and copolymerization) in the crystalline and glassy states both in the field of γ-radiation and as the post-effect recorded when the samples were warmed. The recent experimental data on the unusual oscillations of the polymerization rate of crystalline formaldehyde at 5–30 K are discussed. The mechanical factor (brittle disintegration) is proposed to be responsible for these oscillations.

ChemInform Abstract: Solid-State Chain Photochlorination in Recrystallized Mixtures of Ethene and Chlorine at 30 K.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and characterization of polyimides based on novel isomeric perfluorinated naphthylenediamines

Novel highly fluorinated polyimides containing hexafluoronaphthylene fragment in the main chain were prepared by the two-stage polymerization of 2,7- and 2,6-diaminohexafluoronaphthalenes with 4,4′-oxydiphthalic anhydride: polycondensation in a solution at 80 °C followed by high-temperature solid-state chain extension. The influence of hexafluoronaphthylene fragment isomerism on the key polyimide features – molecular weight, thermal stability, solubility, optical properties – was characterized. Polyimides based on 2,7-diaminohexafluoronaphthalene or easily accessible mixture of isomeric diamines formed the flexible, transparent, and thermostable films.

Cold crystallization and postmelting crystallization of PLA plasticized by compressed carbon dioxide

AbstractThe cold crystallization at temperature Tcc (melting > Tcc > glass transition) and the postmelting crystallization of polylactic acid plasticized by compressed carbon dioxide (CO2) were studied using a high‐pressure differential scanning calorimeter. The kinetics of the two kinds of crystallization were evaluated by the Avrami equation as a function of pressure at certain temperatures. The effects of using talc as a nucleation agent on the two types of crystallization under pressure were also investigated. The results show that compressed CO2 increased the mobility of the polymer chains in solid state, resulting in an increased rate of cold crystallization. The decreased rate of postmelting crystallization was mainly in the nucleation‐controlled region, which indicates that the number of nuclei was decreased by the compressed CO2. The growth rate of the two crystallization types followed the Avrami equation, but the kinetics of each depended upon temperature and pressure. The inclusion of talc accelerated postmelting crystallization but had little effect on cold crystallization. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2630–2636, 2008

Direct spectroscopic evidence of field-induced solid-state chain conformation transformation in a ferroelectric relaxor polymer

Ferroelectric relaxor P(VDF-TrFE-CFE) terpolymer can generate a hysteresis-free polarization of 47mC∕m2 at an electric field of 100MV∕m and is attractive for many potential actuating and sensing applications. Fourier transform infrared spectra under electric field reveal that this large polarization originates from the field-induced crystalline phase transformation. The nonpolar TGTG′ chain conformation in P(VDF-TrFE-CFE) can be converted into polar trans (Tm>4 and T3G) conformation under high electric field and the latter can be effectively aligned to the applied field direction. Furthermore, this conformation transformation is completely reversible and no hysteresis can be observed during the switching of applied electric field. In contrast, normal ferroelectric polymer P(VDF-TrFE) exhibits square polarization loop with very small reversible polarization.

Non-dispersive hole transport in a novel trifluoromethylbiphenylyl substituted PPV derivative

We have studied the optical and electrical properties of a novel electroluminescent polymer, poly[2−(2'-p−trifluoromethyl-phenyl-4',5'-bis(3’’-methylbutoxy))phenyl-1,4- phenylene vinylene], using absorption, photoluminescence (PL), photoluminescent quantum yield (ηPL) and time of flight (TOF) photoconductivity techniques. The absorption spectrum in chloroform shows a broad absorption band peaked at 2.92 eV and the PL spectrum shows a maximum at 2.52 eV with vibronic shoulders at 2.38 eV and 2.24 eV. The film state absorption and PL spectra shifted towards the low energy region and the vibronic features are more pronounced compared to that in dilute solution. This is due to the increase of effective conjugation length in the solid state compared to that in solution. The PL quantum yield of the polymer was found to be 44 % in chloroform and 52 % in solid state. The increase of ηPL in solid state compared to liquid state is due to the constraint on the twisting or bending motion of the polymer chains in solid state. The room temperature TOF transients for positive charges showed non-dispersive nature of transport with a mobility of 3.83 × 10−6 cm2/Vs at an electric field of 2 × 105 V/cm. The variation of hole mobility with applied electric field has been studied and analyzed according to disorder formalism.

Synthesis, Structural and Chemical Characterization of Unsaturated C4- and C10-Bridged Group-4 ansa-Metallocenes Obtained Through a Ring-Closing Olefin Metathesis Reaction

Bis[(5-hexenyl)cyclopentadienyl]zirconium dichloride (3) underwent ring-closure olefin metathesis with loss of ethylene when treated with 10 mol % of the [Cl2(PCy3)2Ru=CHPh] catalyst in refluxing dichloromethane, to yield the large ansa-zirconocene complex [dec-5-ene-1,10-diylbis(η5-cyclopentadienyl)]ZrCl2 (trans-4). Characterization by NMR and by X-ray diffraction revealed that the isolated complex contained a trans-C=C double bond inside the ansa bridge. Similarly, bis[(allyl)cyclopentadienyl]ZrCl2 (7) gave the ansa-metallocene [but-2-ene-1,4-diylbis(η5-cyclopentadienyl)]zirconium dichloride (cis-8) when treated with the same ruthenium metathesis catalysts (10 mol %) under similar conditions, except that a cis-C=C double bond was now found to be present (shown by NMR and X-ray diffraction). The cis-8 complex was used as a homogeneous Ziegler−Natta catalyst for ethylene polymerization [after activation of the metallocene dichloride 8 with MAO (methylalumoxane) or treatment of the corresponding dimethylmetallocene complex 9 with B(C6F5)3]. Complex 8 was also converted into a mixture of (s-cis- and s-trans-η4-butadiene)-ansa-metallocene complexes (s-cis-15/s-trans-15 = 4:5) by treatment with (butadiene)magnesium. The C=C double bond of cis-8 could be hydroborated with 9-BBN or with the H−B(C6F5)2 reagent. Li+[B(C6F5)4−] added to cis-8 to yield an interesting solid-state chain structure in which the [Zr]Cl2 unit and the o-/m-F pairs of two −C6F5 groups were found to be in contact with the central lithium cation in a distorted octahedral coordination environment (as shown by X-ray diffraction). (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Chain Diffusion in Ultralong n-Alkane Crystals Studied by 13C NMR

13C NMR progressive saturation measurements were used to investigate longitudinal relaxation in the crystal phase of semicrystalline alkanes. Novel monodisperse, ultralong n-alkanes were melt crystallized in such a way that they comprised crystals containing extended chains or once-folded chains. The crystalline morphology was confirmed using DSC, SAXS, and WAXS. Quantifying the longitudinal relaxation is critically dependent on an accurate measure of the crystallinity of the sample. Crystallinities were measured using X-ray scattering, calorimetric, and 1H broadline NMR techniques. The longitudinal relaxation is interpreted via a solid-state chain diffusion process. Very high crystallinity was shown to suppress the diffusion. A one-dimensional diffusion model with a single reptation time was shown to represent successfully the relaxation of crystals comprising extended chains. The addition of chain folds was shown to result in a decrease in the diffusion coefficient, although the addition of branches at ...