Juan Shen

Synthesis, characterization, thermal stability and mechanical sensitivity of polyvinyl azidoacetate as a new energetic binder

A new azide polymer, polyvinyl azidoacetate (PVAA), was synthesized through the initial polymerization reaction and subsequent azidation reaction of vinyl chloroacetate. By controlling the appropriate reaction conditions, the PVAA can be prepared with a number average molecular weight in the range of 1.54u2009×u2009104~4.02u2009×u2009104 and polydispersity index in the range of 2.0~4.0. The structure of PVAA was confirmed by elemental analysis, 1H NMR, 13C NMR and ATR-FTIR techniques. The glass transition temperature of PVAA was evaluated by DSC method and the thermal stability of PVAA was tested by DTA and TGA methods. The results show that PVAA has a single glass transition temperature and exhibits a good stability. In addition, the sensitivity properties of PVAA were measured by the China national military standard methods and the compatibilities of PVAA with the energetic components of TNT–based melt cast explosives were studied using the non-isothermal DSC method. The results indicate that PVAA is an insensitive energetic polymer and can be safely used in melt cast explosives.

Synthesis, characterization, and thermal stability properties of PVTNP-co-PVAA through the azidoacetylation of polyvinyl 2,4,6-trinitrophenylacetal

AbstractA new energetic polymer, poly(vinyl 2,4,6-trinitrophenylacetal)-co-poly(vinyl acetate azide) (PVTNP-co-PVAA), was synthesized by a two-step process involving initial chloroacetylation and subsequent azidation of poly(vinyl 2,4,6-trinitrophenylaceta). The synthesized polymers were characterized by elemental analysis, UV-Vis, ATR-FTIR, and 1H NMR techniques. The glass-transition temperature of PVTNP-co-PVAA was evaluated by differential scanning calorimetry (DSC), and the thermal stability of PVTNP-co-PVAA was tested by differential thermal analysis (DTA) and thermogravimetric analysis (TGA). DSC traces showed that PVTNP-co-PVAA had two glass-transition temperatures at −27.53 and 67.05 °C, respectively. DTA and TGA curves showed that the thermo-oxidative degradation of PVTNP-co-PVAA in air was a two-step reaction, and the percentage of degraded PVTNP-co-PVAA reached nearly 100% at 600 °C.n

Synthesis, Characterization, Thermal Stability and Sensitivity Properties of New Energetic Polymers—PVTNP-g-GAPs Crosslinked Polymers

A series of energetic polymers, poly(vinyl 2,4,6-trinitrophenylacetal)-g-polyglycidylazides (PVTNP-g-GAPs), were synthesized via cross-linking reactions of PVTNP with three different molecular weight GAPs using toluene diisocyanate as the cross-linking agent. The structures of these energetic polymers were characterized by ultraviolet visible spectra (UV–Vis), attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR-FTIR), and nuclear magnetic resonance spectrometry (NMR). The glass-transition temperatures of these energetic polymers were measured with differential scanning calorimetry (DSC) method, and the results showed that all the measured energetic polymers have two distinct glass-transition temperatures. The thermal decomposition behaviors of these energetic polymers were evaluated by differential thermal analysis (DTA), thermogravimetric analysis (TGA) and thermogravimetric analysis tandem infrared spectrum (TGA-IR). The results indicated that all the measured energetic polymers have excellent resistance to thermal decomposition up to 200 °C, and the initial thermal decomposition was attributed to the breakdown of azide group. Moreover, the sensitivity properties of these energetic polymers were measured with the national military standard methods and their compatibilities with the main energetic components of 2,4,6-trinitrotoluene (TNT)-based melt-cast explosive were evaluated by using the DTA method. The results indicate that these energetic polymers have feasible mechanical sensitivities and can be safely used with TNT, cyclotetramethylene tetranitramine (HMX), 1,1-diamino-2,2-dinitroethene (FOX-7), 3-nitro-1,2,4-triazol-5-one (NTO) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB).

Direct Formation of Cycloadducts Between Fullerenes and Amino Acids Through Electron-Transfer Processes

Abstract The reactions of [60]fullerene and amino acids in the absence of aldehyde in o-dichlorobenzene (ODCB) at 150 °C have been investigated. Fulleropyrrolidines 1 [C60(CH2N(CH3)CHC6H2(NO2)3)], 2 [C60(CH2N(CH3)CH2)], 3 [C60(CH2NHCH2)], and 5a–b [C60(RCHNHCHR), R˭CH3 (5a), R˭CH2Ph (5b)] were obtained in moderate yields from the reactions of C60 and corresponding amino acids. The reaction of C70 and N-methylglycine in the absence of aldehyde was also studied and was found to give the positional isomers of N-methyl[70]fulleropyrrolidines 6 (1,9-isomer) and 7(7,8-isomer). All products were fully characterized by ultraviolet–visible, Fourier transform–infrared (FT-IR), NMR, and mass spectrometry. The reactions were also carried out in the dark to exclude the possible interference of the photoinduced reactions, and almost the same yields of products were obtained. GRAPHICAL ABSTRACT