Thermal and Combustion Properties of 3,4‐Bis(3‐nitrofurazan‐4‐yl)furoxan (DNTF)

Thermal decomposition of melted 3,4‐bis(3‐nitrofurazan‐4‐yl)furoxan (DNTF) in isothermal conditions was studied. The burning rates of DNTF were measured in the pressure interval of 0.1–15 MPa. The thermal stability of DNTF was found to be close to the stability of HMX, while the burning rate of DNTF was close to the burning rate of CL‐20. The thermocouple measurements in the combustion wave of DNTF showed that combustion of DNTF was controlled by the gas‐phase mechanism. The DNTF vapor pressure was determined from thermocouple measurements and agreed well with data obtained at low temperatures under isothermal conditions.     

Promising CL‐20‐Based Energetic Material by Cocrystallization

A novel cocrystal (NEX‐1) of CL‐20 and MDNT is presented herein. The CL‐20: MDNT cocrystal, obtained in high yield by resonant acoustic mixing, shows new properties versus the discrete components. This is the first example of cocrystallization of CL‐20 where the new material is less sensitive to friction than CL‐20 itself, while demonstrating similar impact and ESD sensitivity. The CL‐20: MDNT cocrystal shows promise in the production of new energetic materials of interest by the cocrystallization of well‐characterized components.     

A New Energetic Salt Semicarbazide 5‐Dinitromethyltetrazolate: A Promising Explosive Alternative

The design and synthesis of new environmentally friendly energetic materials with excellent performance and reliable safety have received considerable attention. A new energetic salt of semicarbazide 5‐dinitromethyltetrazolate (SCZ ⋅ DNMZ) was synthesized by using semicarbazide and 5‐dinitromethyltetrazolate (DNMZ) as raw materials, and fully characterized by using elemental analysis, FT‐IR spectroscopy, ¹H, ¹³C, and ¹⁵N nmR and mass spectrometry. The monocrystal of the salt was obtained and the structure was determined by X‐ray single‐crystal diffractometer. Results show that it belongs to monoclinic space group P 2₁/c with a high density of 1.867 g cm⁻³. The thermal decomposition behavior was tested by DSC and TG‐DTG technologies; the non‐isothermal kinetic parameters for the salt were calculated. The enthalpy of formation for the salt is directly dependent on the combustion heats data with a result of 341.5 kJ mol⁻¹, which is about three times higher than that of RDX. The detonation pressure (P ) and detonation velocitiy (D ) of the salt were determined as 8931 m s⁻¹ and 36.2 GPa, which are also higher than that of RDX. The impact sensitivity was tested with a result of 10.8 J. We can draw a safe conclusion that the salt has provided a promising future by using as a kind of explosive alternative. The discovery also contributes significantly to the expansion and application of the N‐heterocyclic compounds applied as energetic materials.     

4,5‐Bis(5‐tetrazolyl)‐1,2,3‐triazole: Synthesis and Performance

4,5‐Bis(5‐tetrazolyl)‐1,2,3‐triazole (BTT) was synthesized by a new method. Its structure was characterized by IR and ¹³C NMR spectroscopy and elemental analysis (EA). The thermal stability of BTT was investigated by TG‐DSC technique. The kinetic parameters including activation energy and pro‐exponential factor were calculated by Kissinger equation. The combustion heat, detonation products, hygroscopicity, impact, and friction sensitivity were also measured. The formation heat, detonation pressure, and detonation velocity of BTT were calculated. BTT has high detonation pressure and detonation velocity (P=35.36 GPa, D=8.971 km s⁻¹). BTT has potential application prospect as environmentally friendly gas generant, insensitive explosive and solid propellant.     

Diversified Construction of Chromeno[3,4‐c]pyridin‐5‐one and Benzo[c]chromen‐6‐one Derivatives by Domino Reaction of 4‐Alkynyl‐2‐oxo‐2H‐chromene‐3‐carbaldehydes

Silver‐catalyzed three‐component, tandem reactions of 4‐alkynyl‐2‐oxo‐2H‐chromene‐3‐carbaldehydes, amines and various nucleophiles result in the formation of highly functionalized chromeno[3,4‐c]pyridin‐5‐ones in high yields. Gold‐catalyzed [4+2] cycloadditions of 4‐alkynyl‐2‐oxo‐2H‐chromene‐3‐carbaldehydes with alkynes or alkenes have also been achieved to afford benzo[c]chromen‐6‐ones efficiently.

     

Nonlinear optical studies on new conjugated poly{2,2l‐(3,4‐ dialkoxythiophene‐2,5‐diyl) bis[5‐(2‐thienyl)‐1,3,4‐oxadiazole]}s

Three new donor–acceptor type poly{2,2^l‐(3,4‐ dialkoxythiophene‐2,5‐diyl)bis[5‐(2‐thienyl)‐1,3,4‐oxadiazole]}s ( P1, P2, and P3 ) were synthesized starting from thiodiglycolic acid and diethyl oxalate through multistep reactions. The polymerization was carried out using chemical polymerization technique. The optical and charge‐transporting properties of the polymers were investigated by UV‐visible, fluorescence emission spectroscopic and cyclic voltammetric studies. The polymers showed bluish‐green fluorescence in solutions. The electrochemical band gaps were determined to be 2.03, 2.09, and 2.17 eV for P1 , P2, and P3, respectively. The nonlinear optical properties of new polymers were investigated at 532 nm using single beam Z‐scan and degenerate four‐wave mixing (DFWM) techniques with nanosecond laser pulses. The polymers exhibited strong optical limiting behavior due to “effective” three‐photon absorption. Values of the effective three‐photon absorption ( 3PA ) coefficients, third‐order nonlinear susceptibilities (χ⁽³⁾), and figures (F) of merit were calculated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of alcoholic solvents on the conductivity of tosylate‐doped poly(3,4‐ethylenedioxythiophene) (PEDOT‐OTs)

The effects of alcoholic solvents on the charge transport properties of tosylate‐doped poly(3,4‐ethylenedioxythiophene) (PEDOT‐OTs) are investigated. The use of different alcoholic solvents in the oxidative chemical polymerization of 3,4‐ethylenedioxythiophene (EDOT) with iron(III)‐p‐tosylate led to a change in the electrical conductivity of PEDOT‐OTs. For example, PEDOT‐OTs prepared from methanol shows a conductivity of 20.1 S cm^?1 which is enhanced by a factor of 200 as compared to PEDOT‐OTs prepared from hexanol. The variation of charge transport properties on the use of different alcoholic solvents is consistent with the data recorded by UV‐visible and electrospin resonance (ESR) measurements. From XPS experiments, the PEDOT‐OTs samples prepared from different alcoholic solvents were found to have almost the same doping level, suggesting that the number of charge carriers is not responsible for the change in conductivity. Supported by XRD results, it was found that the use of alcoholic solvents with shorter chain length induces more efficient packing of PEDOT chains. It is proposed that the alcoholic solvents associated with the counter ion of PEDOT via hydrogen bonding give rise to a change in the molecular ordering of PEDOT chains during the polymerization step, hence enhancing or depressing the inter‐chain hopping rate of the resulting PEDOT‐OTs. Copyright © 2005 Society of Chemical Industry     

The High‐Pressure Characterization of Energetic Materials: 2‐Methyl‐5‐Nitramino‐2H‐Tetrazole

The isothermal structural properties, equation of state, and vibrational dynamics of 2MNT were studied under high‐pressure using synchrotron XRD and optical Raman and IR microspectroscopy. Analysis of the XRD patterns revealed no indication of a phase transition to near 15 GPa and the pressure‐volume isotherm remained smooth to 15 GPa. Near 15 GPa, significant sample damage was observed from the X‐ray beam which precluded the acquisition of patterns above this pressure. XRD and Raman spectroscopic measurements showed the monoclinic ambient condition phase of 2MNT remains the dominant phase to near 20 GPa, although a shift of the NO₂ IR active vibrational modes to lower frequencies suggested a subtle geometry modification not reflected in the XRD data.     

The High‐Pressure Characterization of Energetic Materials: 1‐Methyl‐5‐Nitramino‐1H‐Tetrazole

Pressure–volume relations and optical Raman and Infrared spectra of polycrystalline 1MNT have been obtained under quasi‐hydrostatic conditions up to 16 and 40 GPa, respectively, by using diamond anvil cell, synchrotron‐based angle‐resolved X‐ray diffraction, and microspectroscopy. The X‐ray measurements show that the pressure–volume relations remain smooth up to 16 GPa at room temperature, while vibrational measurements show no evidence of a phase transition to near 40 GPa. Anomalous increases of several vibrational intensities and bandwidths suggest that subtle molecular distortions and structural modifications occur in the crystal as pressure increases. Decompression experiments indicate the structural modifications are reversible.     

A DFT Study on the Structures and Energies of Isomers of 4‐Amino‐1,3‐dinitro‐1,2,4‐triazol‐5‐one‐2‐oxide: New High Energy Density Compounds

Isomers of 4‐amino‐1,3‐dinitrotriazol‐5‐one‐2‐oxide (ADNTONO) are of interest in the contest of insensitive explosives and were found to have true local energy minima at the DFT‐B3LYP/aug‐cc‐pVDZ level. The optimized structures, vibrational frequencies and thermodynamic values for triazol‐5‐one N‐oxides were obtained in their ground state. Kamlet‐Jacob equations were used to evaluate the performance properties. The detonation properties of ADNTONO (D=10.15 to 10.46 km s⁻¹, P=50.86 to 54.25 GPa) are higher compared with those of 1,1‐diamino‐2,2‐dinitroethylene (D=8.87 km s⁻¹, P=32.75 GPa), 5‐nitro‐1,2,4‐triazol‐3‐one (D=8.56 km s⁻¹, P=31.12 GPa), 1,2,4,5‐tetrazine‐3,6‐diamine‐1,4‐dioxide (D=8.78 km s⁻¹, P=31.0 GPa), 1‐amino‐3,4,5‐trinitropyrazole (D=9.31 km s⁻¹, P=40.13 GPa), 4,4′‐dinitro‐3,3′‐bifurazan (D=8.80 km s⁻¹, P=35.60 GPa) and 3,4‐bis(3‐nitrofurazan‐4‐yl)furoxan (D=9.25 km s⁻¹, P=39.54 GPa). The  NH₂ group(s) appears to be particularly promising area for investigation since it may lead to two desirable consequences of higher stability (insensitivity), higher density, and thus detonation velocity and pressure.     

Hydrogen‐bonding interaction between poly(ε‐caprolactone) and low‐molecular‐weight amino compounds

The specific interactions between several low‐molecular‐weight diamino compounds and poly(ε‐caprolactone) (PCL) have been investigated by FT‐IR. It was found that PCL and 3,3′‐diaminodiphenylmethane (3,3′‐DADPM) interact through strong intermolecular hydrogen bonds in the blend. Thermal and mechanical properties of PCL/3,3′‐DADPM blends were investigated by DSC and tensile measurements, respectively. The glass transition temperature of the blend increases while both the melting point and the elongation‐at‐break of the blend decrease with the increase of 3,3′‐DADPM content. Besides 3,3′‐DADPM, several other low‐molecular‐weight compounds containing two amino groups, such as o‐phenylenediamine or 1,6‐diaminohexane, were also added into PCL and the corresponding blend systems were investigated by FT‐IR and DSC. The effect of the chemical structure of the additives on the properties of PCL is discussed. © 2001 Society of Chemical Industry     

Evaluation of 4‐(Dimethylsilyl) Butyl Ferrocene Grafted HTPB as a Burning Rate Modifier in Composite Propellant Formulation using Bicurative System

High burning rate composite propellants are achieved by incorporation of fine particles of oxidizer, transition metal oxides, and liquid ballistic modifiers. However, they pose processing problems, inertness to the composition and migration related issues. To overcome such problems, an attempt was made to incorporate ferrocenyl grafted HTPB as a burning rate modifier by partly replacing HTPB from 10 % to 50 % using TDI/ IPDI bicurative system and to study their processability in terms of viscosity, mechanical, thermal, sensitivity, and ballistic properties. The data on viscosity reveal that there is a marginal enhancement in end of mix viscosity as percentage of ferrocenyl grafted HTPB increases. The mechanical data reveal that tensile strength and elastic modulus increases, whereas percentage elongation decreases compared to base composition. The results on thermal properties infer that, as the percentage of ferrocenyl grafted HTPB increases, onset decomposition temperature decreases. The impact and friction sensitivity data also envisage that sensitivity increases in comparison to base composition. The data on ballistic properties revealed that there is ca. 53 % increase in burning rate, while decrease in “n” value from 0.39 to 0.2 was obtained compared to base composition.     

Poly(vinyl pyrrolidone‐co‐vinyl acetate)‐graft‐poly(ε‐caprolactone) as a compatibilizer for cellulose acetate/poly(ε‐caprolactone) blends

Poly(vinyl pyrrolidone‐co‐vinyl acetate)‐graft‐poly(ε‐caprolactone) (PVPVAc‐g‐PCL) was synthesized by radical copolymerization of N‐vinyl‐2‐pyrrolidone (VP)/vinyl acetate (VAc) comonomer and PCL macromonomer containing a reactive 2‐hydroxyethyl methacrylate terminal. The graft copolymer was designed in order to improve the interfacial adhesiveness of an immiscible blend system composed of cellulose acetate/poly(ε‐caprolactone) (CA/PCL). Adequate selections of preparation conditions led to successful acquisition of a series of graft copolymer samples with different values of molecular weight ( ), number of grafts (n), and segmental molecular weight of PVPVAc between adjacent grafts (M_n (between grafts)). Differential scanning calorimetry measurements gave a still immiscible indication for all of the ternary blends of CA/PCL/PVPVAc‐g‐PCL (72 : 18 : 10 in weight) that were prepared by using any of the copolymer samples as a compatibilizer. However, the incorporation enabled the CA/PCL (4 : 1) blend to be easily melt‐molded to give a visually homogeneous film sheet. This compatibilizing effect was found to be drastically enhanced when PVPVAc‐g‐PCLs of higher and M_n (between grafts) and lower n were employed. Scanning electron microscopy revealed that a uniform dispersion of the respective ingredients in the ternary blends was attainable with an assurance of the mixing scale of several hundreds of nanometers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

(2,2‐Diphenyl‐[1,3]oxathiolan‐5‐ylmethyl)‐(3‐phenyl‐propyl)‐amine: a Potent and Selective 5‐HT1A Receptor Agonist

A selective 5‐HT _1A receptor agonist : A new series of ligands acting at 5‐HT_1A serotonin receptor were identified. Among them (2,2‐diphenyl‐[1,3]oxathiolan‐5‐yl‐methyl)‐(3‐phenyl‐propyl)amine (shown) possesses outstanding activity (pK_i=8.72, pD₂=7.67, E_max=85) and selectivity (5‐HT_1A/α_1D>150), and represents a new 5‐HT_1A agonist chemotype.

     

Synthesis and characterization of poly(ε‐caprolactone)‐b‐poly(ethylene glycol)‐b‐poly(ε‐caprolactone) triblock copolymers with dibutylmagnesium as catalyst

Two series of poly(ε‐caprolactone)‐b‐poly(ethylene glycol)‐b‐poly(ε‐caprolactone) triblock copolymers were prepared by the ring opening polymerization of ε‐caprolactone in the presence of poly(ethylene glycol) and dibutylmagnesium in 1,4‐dioxane solution at 70°C. The triblock structure and molecular weight of the copolymers were analyzed and confirmed by ¹H NMR, ¹³C NMR, FTIR, and gel permeation chromatography. The crystallization and thermal properties of the copolymers were investigated by wide‐angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). The results illustrated that the crystallization and melting behaviors of the copolymers were depended on the copolymer composition and the relative length of each block in copolymers. Crystallization exothermal peaks (T_c) and melting endothermic peaks (T_m) of PEG block were significantly influenced by the relative length of PCL blocks, due to the hindrance of the lateral PCL blocks. With increasing of the length of PCL blocks, the diffraction and the melting peak of PEG block disappeared gradually in the WAXD patterns and DSC curves, respectively. In contrast, the crystallization of PCL blocks was not suppressed by the middle PEG block. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Random copolymerization of 2,2‐dimethyltri methylene carbonate and ε‐caprolactone using a rare‐earth tris(4‐tert‐butylphenolate)s as a single‐component initiator

Highly random copolymers of 2,2‐dimethyltrimethylene carbonate (DTC) and ε‐caprolactone (CL) were synthesized by single component rare‐earth tris(4‐tert‐butylphenolate)s [Ln(OTBP)₃] for the first time. The influences of reaction conditions on the copolymerization initiated by La(OTBP)₃ have been examined in detail. The monomer reactivity ratios of DTC and CL determined by the Fineman–Ross method are 4.0 for r_DTC and 0.27 for r_CL. The microstructure of the copolymer was determined by the analyses of the diads DTC–DTC, DTC–CL, CL–DTC and CL–CL of the ¹H NMR spectra. The high degree of randomness of the chain structure was further confirmed by the ¹³C NMR spectra and differential scanning calorimetry. The thermal properties of the copolymers as a function of composition are reported. The mechanism investigated by ¹H NMR data indicates that the rare‐earth tris(4‐tert‐butylphenolate)s initiate the ring‐opening copolymerization of DTC and CL with acyl‐oxygen bond cleavages of the monomers. Copyright © 2004 Society of Chemical Industry     

Computational Studies on Nitro,Nitramino, and Dinitramino Derivatives of 1‐Aminoazadiboridine as High Energetic Material

Computational studies were performed to determine the thermodynamic and explosive characteristics of high energy materials formed by placing explosophores such as nitro (−NO₂), nitramino (−NHNO₂), and dinitramino (−N(NO₂)₂) groups on 1‐aminoazadiboridine. G3 level calculations were made to determine the gas phase heat of formation of the designed species. In addition to the above, condensed phase heat of formation was also determined by evaluating the sublimation enthalpy. Crystal densities of title compounds were predicted with the help of a wave function analysis (WFA) program and were found to be in the range of 1.55–1.83 g cm⁻³. Bond dissociation energies of various possible bond rupture routes of the designed molecules were calculated at DFT‐B3LYP/6‐311G(d,p) level and attempt was made to identify the trigger linkage. Impact sensitivity was evaluated theoretically by employing a method based on statistical parameters determined from electrostatic potential data. Results show that the designed molecules are highly energetic and their corresponding detonation properties place them in the category of safe and high performance explosive materials.