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DOE OSTI · 1768064

Probing High-Pressure Structural Evolution in Polyurea with In Situ Energy-Dispersive X-ray Diffraction and Molecular Dynamics Simulations

Eastmond, Tyler·Hu, Jing·Alizadeh, Vahidreza·Hrubiak, Rostislav·Oswald, Jay·Amirkhizi, Alireza·Peralta, Pedro
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Abstract

Polyurea, an elastomer with a phase-segregated microstructure, has been proven as an effective coating in defense applications. To gain a more complete understanding of the high-pressure atomic-level morphology of these phases and to validate molecular dynamics (MD) simulations, multi-angle energy-dispersive X-ray diffraction experiments were performed in situ up to pressures of ~6 GPa at room temperature. Structure factors were obtained and compared to MD simulations with an average error of less than 5% between major peak positions. The first sharp diffraction peak shifted from 4.56 Å to lower d-spacing with pressure, indicating compression between hard segments. This was further supported by the behavior of a peak at ~3.86 Å from the pair distribution function (PDF), suspected to represent π-stacking and separation between soft segments. Compression within the hard segments themselves is minimal as low-r peaks in the PDF are not greatly affected by pressure.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRYAromatic compoundsChemical structureHydrocarbonsPhysical and chemical processesUrea

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Eastmond, Tyler, Hu, Jing, Alizadeh, Vahidreza, Hrubiak, Rostislav, Oswald, Jay, Amirkhizi, Alireza, Peralta, Pedro. 2021-01-11. Probing High-Pressure Structural Evolution in Polyurea with In Situ Energy-Dispersive X-ray Diffraction and Molecular Dynamics Simulations. https://doi.org/10.1021/acs.macromol.0c02266

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