ABSTRACT:This investigation uses the Gaussian 98 program, density functional theory (DFT) B3LYP/6-31G(d,p), and ab initio MP2/6-31G(d,p) and HF/6-31G(d) methods to model energetic diguanidinium 5,5Ј-azotetrazolate (GZT) ionic species in order to determine their decomposition mechanisms. GZT was initially cracked into two guanidinium cations (G ϩ ) and a 5,5Ј-azotetrazolate anion (ZT 2Ϫ ). Three routes-the elimination of a hydronium ion (H ϩ ), the elimination of a hydrogen radical (H⅐), and the elimination of an amine radical (⅐NH 2 )-are suggested for the decomposition of the G ϩ cation, and three routessingle ring opening, double ring opening and NON bond cleavage outside the ring-are proposed for the further decomposition of the ZT 2Ϫ anion. Fourteen decomposition species were obtained on splitting both the cation and anion. This result reveals the reliability of the aforementioned decomposition mechanisms. The transition state species were also obtained using a two-structure or three-structure synchronous transit-guided quasi-Newton (STQN) between the Cartesian coordinates of related particles at specific decomposition stages in this research. The corresponding activation energies in all decomposition stages were considered to infer the most feasible pathways of GZT decomposition.

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A hybrimer based on epoxy resin and phenyl-siloxane was prepared by polymerization and a solgel condensation reaction in which Eporite-904 (807 g/eq) bisphenol-A-type epoxy resin, 3-isocyanatopropyltriethoxysilane (IPTES) and phenyltriethoxysilane (PTEOS) acted as precursors. The thermal and optical properties of the epoxy/siloxane hybrimer were studied. The thermogravimetric analysis (TGA) results implied that the hybrimer could increase the crosslink density and enhance the thermal properties. The optical properties were measured after thermal and UV aging. The refractive indexes of the epoxy/siloxane hybrimers were 1.66-1.70, and the transmittances of the cured hybrimers were above 90% in the visible wavelength. After a 120˚C/24-h thermal aging test, the decreases in the refractive index and transmittance were less than 5% and 20% respectively. The epoxy/siloxane hybrimers also showed low discoloration upon thermal aging at 120˚C for 24 h under an air atmosphere.

Three epoxy resins were examined in this study: Eporite-901 (474 g/eq), Eporite-904 (807 g/eq) and Eporite-909 (1915 g/eq), which are bisphenol-A-type epoxy resins. In this study, we used an amine terminated organically modified silicate (Ormosil) that was compatible with the diglycidyl ether of bisphenol-A epoxy to partially replace the epoxy resin at various ratios, cured by hexahydrophthalic anhydride (HHPA). The thermal and optical properties of the Ormosil-modified epoxy resins (Epoxy/Ormosil) were studied. The M n and M w of the resulting hybrids were in the range of 10668-31450 and 30617-120422, respectively, with a polydispersity index range of 2.870-3.829. The thermogravimetric analysis (TGA) results implied that Ormosil can raise the crosslink density and enhance the thermal properties. The optical properties were measured after curing and thermal aging of the polymer films with thickness around 8-10 mm. The refractive indexes of the Epoxy/Ormosil hybrids were 1.62-1.68, and the transmittances of the cured composites were above 85% in the visible wavelength.The key attributes of Epoxy/Ormosil hybrids that make them attractive materials for LEDs including their high transparency in the UV-visible region, controlled refractive index (RI), and excellent thermal resistance.

Ethene and two kinds of nitrating reagents (HNO 3 and N 2 O 5 ) were included in respective molecular systems, which progressed through a two-stage electrophilic and free radical nitrosubstitution, resulting in the corresponding nitroethene compounds. Subsequent halogenation (using Cl 2 and Br 2 ) and amination (using ammonia) were then performed, also by electrophilic and radical substitution, to produce the target 1,1-diamino-2,2-dinitroethene (FOX-7) derivatives. All transition state species were identified using a two-or three-structure Synchronous Transit-Guided Quasi-Newton between the Cartesian coordinates of the related molecular systems at specific reaction stages. The modeling results suggest that N 2 O 5 is the better agent for nitration and bromine is suitable for use in halogenation. The comparable activation energies throughout the reaction stages were considered to imply the most feasible pathways of FOX-7 synthesis.