Acceleration of decomposition of CL-20 explosive under nanoconfinement

Bari, Rozana; Denton, Aric A.; Fondren, Zachary T.; McKenna, Gregory B.; Simon, Sindee L.

doi:10.1007/s10973-019-09027-5

Cited by 7 publications

(3 citation statements)

References 30 publications

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“…26 In the present study, the nanoconfinement of GDC-0276 was performed using nanopore glass beads, so-called controlled pore glass (CPG). The pore sizes of the CPGs used here varied Imbibing the GDC-0276 into the nanopores was carried out using a method developed previously in our labs: 29 a solution of GDC-0276 in acetone was imbibed into the nanopore glass beads (CPGs) and the acetone was allowed to evaporate. The procedure was repeated until the mass of GDC-0276 reached approximately 50% of that needed for complete pore filling.…”

Section: Experimental Methodsmentioning

confidence: 99%

Isothermal Crystallization Monitoring and Time–Temperature-Transformation of Amorphous GDC-0276: Differential Scanning Calorimetric and Rheological Measurements

et al. 2020

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Cold crystallization of amorphous pharmaceuticals is an important aspect in the search to stabilize amorphous or glassy compounds used as amorphous pharmaceutical ingredients (APIs). In the present work, we report results for the isothermal crystallization of the compound GDC-0276 based on differential scanning calorimetric and rheometric measurements. The kinetics of isothermal crystallization from the induction time to the completion of crystallization can be described by the classic Johnson–Mehl–Avrami (JMA) equation. The time–temperature-transformation (TTT) diagrams were constructed for two time pointsthat of induction and that of completion of crystallization. The results show that the rheological measurement for GDC-0276 has a better overall sensitivity in detection of the early stage nucleation and, consequently, detects the onset of crystallization sooner than does the differential scanning calorimetry. Rheological measurements were also used to obtain the temperature dependence of the viscosity of GDC-0276 and the relevant parameters were used in a modified form of the JMA model to describe the temperature dependence of the crystal induction and completion times, that is, the TTT diagram for the material. In the modification, we assumed that the kinetics followed the viscosity to the 0.75 power as suggested by the recent work of Huang et al. (Huang, C., et al., J. Chem. Phys. 2018, 149, 054503). The relationship and the possible impact on crystallization kinetics of the break-down of the Stokes–Einstein relation in glass-forming liquids are discussed. From the crystallization kinetics modeling, the solid–liquid interfacial surface tension σSL was obtained for GDC-0276 and was compared with that obtained from the melting point depression measurements of the material confined in nanoporous glasses. The differences between the values from the two methods are discussed.

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Section: Experimental Methodsmentioning

confidence: 99%

Isothermal Crystallization Monitoring and Time–Temperature-Transformation of Amorphous GDC-0276: Differential Scanning Calorimetric and Rheological Measurements

et al. 2020

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“…Polymerization of methyl methacrylate (MMA) can result in different molecular weights, polydispersities, and tacticities when confined in CPG with weak interfacial interactions, indicating restriction of chain-scale orientation and conformation, whereas at the monomer scale there is no evidence of conformational change in CPG with weak interfacial interactions. In addition, thermal degradation of polymers can be significantly suppressed in CaRI, whereas the thermal decomposition of some small molecules are accelerated in CPG. , …”

Section: Introductionmentioning

confidence: 99%

“…In addition, thermal degradation of polymers can be significantly suppressed in CaRI, 13 whereas the thermal decomposition of some small molecules are accelerated in CPG. 21,22 In this study, we focus on the molecular glass system, N,N′bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD). We per- form T g and vibrational spectroscopy measurements on TPD confined in both CaRI and CPG systems with various pore sizes.…”

Section: ■ Introductionmentioning

confidence: 99%

Effect of Nanopore Geometry in the Conformation and Vibrational Dynamics of a Highly Confined Molecular Glass

et al. 2021

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The effect of nanoporous confinement on the glass transition temperature (T g) strongly depends on the type of porous media. Here, we study the molecular origins of this effect in a molecular glass, N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD), highly confined in concave and convex geometries. When confined in controlled pore glass (CPG) with convex pores, TPD’s vibrational spectra remained unchanged and two T g’s were observed, consistent with previous studies. In contrast, when confined in silica nanoparticle packings with concave pores, the vibrational peaks were shifted due to more planar conformations and T g increased, as the pore size was decreased. The strong T g increases in concave pores indicate significantly slower relaxation dynamics compared to CPG. Given TPD’s weak interaction with silica, these effects are entropic in nature and are due to conformational changes at molecular level. The results highlight the role of intramolecular degrees of freedom in the glass transition, which have not been extensively explored.

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Two-dimensional nanoscale MoS2 for thermal catalysis of dihydroxylammonium-5,5′-bistetrazole-1,1′-diolate (TKX-50)

Xiong

Bai

et al. 2020

J Therm Anal Calorim

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Acceleration of decomposition of CL-20 explosive under nanoconfinement

Cited by 7 publications

References 30 publications

Isothermal Crystallization Monitoring and Time–Temperature-Transformation of Amorphous GDC-0276: Differential Scanning Calorimetric and Rheological Measurements

Isothermal Crystallization Monitoring and Time–Temperature-Transformation of Amorphous GDC-0276: Differential Scanning Calorimetric and Rheological Measurements

Effect of Nanopore Geometry in the Conformation and Vibrational Dynamics of a Highly Confined Molecular Glass

Two-dimensional nanoscale MoS2 for thermal catalysis of dihydroxylammonium-5,5′-bistetrazole-1,1′-diolate (TKX-50)

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