A new fluorocarbon adhesive:Inhibiting agglomeration during combustion of propellant via efficient F-Al_(2)O_(3) preignition reaction

Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structured fluorinated alcohol compound(PFD)was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization(HTPE)binder;that is,a unique fluorinated polyether(FTPE)binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking curing.The FTPE was applied in aluminum-based propellants for the first time.Due to the complete release of fluorinated organic active segments in the range of 300℃to 400℃,the burning rate of FTPEbased propellant increased from 4.07(0%PFD)to 6.36 mm/s(5%PFD),increased by 56.27%under 1 MPa.The reaction heat of FTPE propellants increased from 5.95(0%PFD)to 7.18 MJ/kg(5%PFD)under 3.0 MPa,indicating that HTPE binder modified with PFD would be conducive to inhibiting the D90 of condensed combustion products(CCPs)dropped by 81.84%from 75.46(0%PFD)to 13.71μm(5%PFD)under 3.0 MPa,in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the propellants.Those results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments,which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion,and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.

Simultaneous Determination of Halogen Compounds and Sulfur Oxides in Flue Gas by Ion Chromatography

Ion chromatography （IC） is a suitable analytical method for the determination of anions. As analytical methods for the halogen compounds in flue gas, those of bromine compound, fluorine compound, chlorine （Cl2） and hydrogen chloride （HCI） are listed in JIS. However, IC has not been adopted in JIS except for HCI and C12. Because the carbon dioxide in flue gas is absorbed in a 0.1 M sodium hydroxide solution as an absorber, it is interfered with the measurement of F^- and Cl^- ions. This paper describes the development of the pretreatment equipment for the flue gas analysis by IC, and its applications to real flue gas analysis. The F^-, Cl^-, Br^- and SO4^2- in the absorbing solution can be clearly separated by IC using the pretreatment equipment. The halogen compounds and sulfur oxides in flue gas can be simultaneously determined by IC.

Substitution Process and Valent State of Samarium Ion in Perovskite Binary Fluorides

The lattice sites occupied by samarium ions in KMgF3 were ascertained. The relationship between valent state of samarium ion in hosts and substituted lattice sites was investigated using fluorescent spectra. It is found that the valent state of samarium in different cationic lattice sites is different. The internal relation between the valent state of samarium ion and occupied lattice site was discussed.

Hydrogen Sensing Property of Lanthanum Complex Fluoride

Four potentiometer sensor cells have been prepared by using La0.95Pb0.05F2.95 as solid electrolyte(SE) and various materials as electrodes. The sensor cell `Bi(BiF3)|SE|Pt' exhibits the best performance with its 90% response time as short as 75 s to 100 Pa H2 in air at room temperature and with its linear decrease of electromotive force (EMF) with an increase of the logarithm of hydrogen partial pressure in the experimental range. The sensor cell shows weaker response to CO.

Synthesis and Single-crystal X-ray Studies of (E)-ethyl 2-fluoro-2-(3-oxoisobenzofuran-1(3H)-ylidene) Acetate

The title compound （E）-ethyl 2-fluoro-2-（3-oxoisobenzofuran-1（3H）-ylidene） aceta- te was synthesized as an unexpected product by the reaction ofphthalyl dichloride with bis-silylenol ether, which is not in accordance with our previous studies. The title compound was characterized by single-crystal X-ray diffraction, 1H NMR, 13C NMR, 19F NMR, GCMS, HRMS and IR. The crystal （C12HgFO4, Mr = 236.19） belongs to the monoclinic system, space group P21/c, a = 19.1609（8）, b = 7.9831（3）, c = 13.7715（6） A, V= 2106.13（15） A3, Z= 8, Dx = 1.490 Mg m-3, MoKa radiation, 2 = 0.71073 A,μ = 0.12 mm-1, F（000） = 976, the final R = 0.025 and wR = 0.1300 for 4505 observed reflections with I〉 2σ（I）.

Synthesis and Bioactivity of Novel Fluorinated Heteroaromatic Ureas

In order to find new urea cytokinins, a series of novel fluorinated heteroaromatic ureas have been designed and synthesized, The crystal structure of 3g was further determined by single crystal X-ray diffraction to obtain the structural feature of this class of urea compounds. The preliminary bioassay showed that some title compounds have good cytokinin activity.

Recent Advances in the Electrochemical Defluorinative Transformations of C-F Bonds

Organic fluorine compounds are ubiquitous and pivotally important organic molecules,yet their activation and transformation have long been a formidable challenge due to the high energy and low reactivity of C-F bonds.Organic electrosynthesis,an environmentally benign synthetic method in organic chemistry,enables a myriad of chemical transformations without the need for external redox reagents.In recent years,organic electrochemistry has emerged as a powerful tool for achieving the activation and transformation of C-F bonds in fluorine-containing compounds.This review aims to succinctly recapitulate the latest advancements in the electrochemical defluorinative transformations of C-F bonds and to delve into the reaction design,mechanistic insights,and developmental prospects ofthese methods.

Facile Preparation of Fluoroalkyl End-Capped Vinyltrimethoxysilane Oligomer/Sand Composites Possessing Superoleophilic/Superhydrophobic Characteristic: Application to Oil/Water Separation and Selective Removal of Fluorinated Aromatic Compounds from Aqueous Methanol Solution

Fluoroalkyl end-capped vinyltrimethoxysilane oligomer [RF-(CH2-CHSi(OMe)3)n-RF: n = 2, 3, RF = CF(CF3)OC3F7: RF-(VM)n-RF], was applied to the facile preparation of the corresponding oligomer/sand (Ottawa sand: OS) composites [RF-(VM-SiO3/2)n-RF/OS] through the sol-gel reaction of the oligomer in the presence of micro-sized OS particles (590 - 840 μm) under alkaline conditions at room temperature. FE-SEM (Field Emission Scanning Electron Micrograph) images showed that the obtained composites consist of the RF-(VM-SiO3/2)n-RF oligomeric nanoparticles and the micro-sized OS particles. Interestingly, the RF-(VM-SiO3/2)n-RF/OS composites thus obtained can provide the superoleophilic/superhydrophobic characteristic on the composite surface, applying to the separation of not only the mixture of oil/water but also the W/O emulsion to isolate the transparent colorless oil. The fluorinated oligomeric OS composites were also found to be applicable to the selective removal of fluorinated aromatic compounds from an aqueous methanol solution. Especially, it was demonstrated that the fluorinated OS composites can supply a higher efficient and smooth separation ability for the separation of the mixture of oil and water than that of the corresponding fluorinated micro-sized controlled silica gel (μ-SiO2) composites (average particle size: 9.5 μm), which were prepared under similar conditions. In addition to the separation of oil/water, the fluorinated OS composites provided higher and more selective removal ability for the fluorinated aromatic compounds from aqueous solutions than that of the μ-SiO2 composites.

Fluorine-containing pharmaceuticals approved by the FDA in 2020:Synthesis and biological activity

Thirteen new fluorine-containing drugs,which have been granted approval by the US Food and Drug Administration(FDA)in 2020,are profiled in this review.Therapeutic areas of these new fluorinated pharmaceuticals include medicines and diagnostic agents for Cushing's disease,neurofibromatosis,migraine,Alzheimer's disease,myelodysplastic syndromes,hereditary angioedema attacks,and various cancers.Molecules of these approved drugs feature aromatic fluorine(Ar-F)(11 compounds),aromatic Ar-CF_(3)(1),aliphatic CHF(1)and CF_(2)(1)groups.For each compound,we provide a spectrum of biological activity,medicinal chemistry discovery,and synthetic approaches.

Michael Addition Reaction of Fluorinated Nitro Compounds

The Michael addition reactions of fluorinated nitro compounds with electron deficient olefins to give γ-fiuoro-γ-nitro-esters, nitriles and ketones which bear a fluorinated quaternary carbon center were reported. The reactions were promoted by TMG, affording the desired adducts in acceptable to good yields.

Combustion mechanism of fluorinated organic compound-modified nano-aluminum composite particles:Towards experimental and theoretical investigations

Fluorinated Organic Compounds(FOCs)are commonly used as modifiers for Aluminum(Al)powder to improve its ignition,combustion,and agglomeration characteristics.However,the effects of FOCs on combustion and inhibition mechanisms of agglomeration of Al powder are not well understood.In this paper,based on the experimental study of Fluorinated Graphite(FG)-modified Al matrix composite particles,the combustion and aggregation inhibition mechanisms of FOCs on Al particles were studied by the quantum chemical calculation at B3LYP/6-311+G(d,P)and G3//B3LYP/6-311+G(d,p)levels.The flame behavior and single particle burning behavior of FG-modified samples were compared through ignition experiments,and the characteristic spectra of Al related oxides of different samples in the initial ignition stage were captured.It is found that FG increases the burning intensity of Al composite samples significantly,while it decreases the emission intensity of Al secondary oxides.Quantum chemical calculation results show that the thermal decomposition intermediates of FOCs,namely C_(2)F_(4),can react with AlO and Al_(2)O,which weakens the characteristic emission intensity of AlO and Al_(2)O in the sample,and thus inhibits the formation of Al_(2)O_(3)in the combustion process.These results contribute to enriching the combustion dynamics model of Al-FOCs reaction system.

Bridgman growth of LiYF_4 single crystal in nonvacuum atmosphere

Using LiF and YF3 as starting materials,we prepare feed material from fluorides according to the molar ratio of LiF：YF3=51.5：48.5.The anhydrous LiYF4 polycrystalline material is synthesized via the fluoridation process with a dried HF flow at elevated temperature.By charging the feed material and adding a small amount of active carbon powder in a sealed platinum crucible,the crystal can be grown via the vertical Bridgman method in a nonvacuum atmosphere.This is possible because the oxidization and volatilization of the melt is avoided.Using optimum conditions,that is,a growth rate of 0.5-0.6 mm/h and a temperature gradient of 25-30℃/cm across the solid-liquid interface under a furnace temperature of 920-930℃,the colorless crystal LiYF 4 with the size of φ25 × 50 （mm） is successfully grown.The optical transmittance of the crystal is as high as 85% above the absorption edge at 190 nm.The induced absorption bands are observed below 700 nm in the transmission spectrum after the crystal is subjected to a high dose of γ-ray irradiation.

Polymeric 32-channel arrayed waveguide grating multiplexer using fluorinated poly (ether ether ketone)

In wavelength division multiplexing (WDM) systems, arrayed waveguide grating (AWG) multiplexer is a key component. Polymeric AWG multiplexer has recently attracted much attention due to its low cost processing and a potential of integration with other devices. Fluorinated polyether ether ketone (FPEEK) is excellent material for fabrication of optical waveguides due to its low absorption loss at 1.55-μm wavelength and high thermal stability. A 32-channel AWG multiplexer has been designed based on the grating diffraction theory and fabricated using newly synthesized FPEEK. During the fabrication process of the polymer/Si AWG device, spin coating, vaporizing, photolithographic patterning and reactive ion etching (RIE) are used. The AWG multiplexer measurement system is based on a tunable semiconductor laser, an infrared camera and a Peltier-type heater. The device exhibits a wavelength channel spacing of 0.8 nm and a center wavelength of 1548 nm at room temperature.

Simulation study of the NA/σ's dependence of DOF for 193-nm immersion lithography at 65-nm node

Recently, ArF iininersion lithography has been considered as a promising method after ArF dry lithography by a factor of refractive index n of the liquid filled into the space between the bottom lens and wafer, in the case of 193-nm exposure tools, water （n - 1.44） has been found as the best liquid, We explore the NA/σ＇s dependence of depth of focus （DOF） under 3/4 annular and 3/4 quasar illumination by resist imaging simulation, Line/space pairs of line-to-space ratios 1：1, 1：2, 1：4 on binary mask are considered. Finally, we explored the high NA＇s dependency of DOF and gaw~ the explanation for the peak value of DOF through three-beam imaging process, MicroCruiser 2.0, Prolith version 8,0,2 and k2 factor based on the Rayleigh equation.

Synthesis and photoswitching properties of azobenzene liquid crystals with a pentafluorobenzene terminal

The fluorine-substituted benzoate ester rod-shaped liquid crystals containing an azobenzene side chain linked with terminal double bonds were synthesized and characterized.The mesophase and photoswitching properties were determined by polarizing optical microscopy（POM）,differential scanning calorimetry（DSC） and UV-visible spectrometry.The rod-shaped compound 4a having an odd number of carbon atoms in the alkyl chains exhibits nematic phase and SmA type phase whereas compound 4b having an even number of carbon atoms showed only nematic phase.Both fluorinecontaining compounds 4c and 4d showed only SmA type phases.The photoswitching properties of these compounds showed a rate of trans to cis isomerization ranging 19-20 s,whereas reverse process took around 230 min in solution.These materials may be ideal in the field of optically rewritable applications where both on and off rates should be crucial.

Raman spectra of undoped and uranium doped CaF_2 single crystals

Raman scattering experiments for nominally pure and uranium doped CaF2 single crystals were presented. In all crystals, the Raman active T2g vibration mode of CaF2 was observed, whose frequency shift and full-width at half-maximum (FWHM) broadening correspond well with defects and impurities in CaF2 lattice. Additional Raman peaks develop in nominally pure CaF2 with high etch pits density and U6+:CaF2 crystals. Part of additional Raman peaks in the experimental results, which are assumed due to vibration modes from F- interstitials and vacancies, are in well agreement with the theoretical predications by employing the Green-function formulation.

Research of cornea section's shape ablated by 193-nm ArF laser spots

The ablation theory of cornea and biology effect by 193-nm ArF excimer laser axe introduced. The ablation tracks model is put forward to make laser spots scan axound cornea by many steps and many areas to change cornea curvature. The corneal average ablation curve is calculated by software so as to explain the feasibility of the ablation tracks model. By analyzing the actual ablation shapes of many axbitrary cornea sections, the optimal ablation method for deciding the random position of every laser spot in every ablation track is obtained. Experiments combining the ablation model with the device testify the energy stability of laser spots and the accuracy of rectifying anisometropia.

C–F bond activation under transition-metal-free conditions

The unique properties of fluorine-containing organic compounds make fluorine substitution attractive for the development of pharmaceuticals and various specialty materials,which have inspired the evolution of diverse C–F bond activation techniques.Although many advances have been made in functionalizations of activated C–F bonds utilizing transition metal complexes,there are fewer approaches available for nonactivated C–F bonds due to the difficulty in oxidative addition of transition metals to the inert C–F bonds.In this regard,using Lewis acid to abstract the fluoride and light/radical initiator to generate the radical intermediate have emerged as powerful tools for activating those inert C–F bonds.Meanwhile,these transition-metal-free processes are greener,economical,and for the pharmaceutical industry,without heavy metal residues.This review provides an overview of recent C–F bond activations and functionalizations under transition-metal-free conditions.The key mechanisms involved are demonstrated and discussed in detail.Finally,a brief discussion on the existing limitations of this field and our perspective are presented.

Reactions of enamines with fluorinated acyl chlorides----Synthesis of fluorinated 1,3-diketones and 1,3-keto-aldehydes

The reactions of enamines (1a–b, 4, 6) with fluorinated acyl chlorides (2a–d ) produced fluorinated 1,3-diketones (3a–f) and 1,3-keto-aldehydes (7a–c) in good yields as well as byproducts fluorinated acylamides (5a–c). It is proposed that the reactions involve nucleophilic attack by the C-atom and/or N-atom of the enamines on acyl carbon of the fluorinated acyl chlorides.