Structural and mechanical stability of clathrate hydrates encapsulating monoatomic guest species

K Xu and YW Lin and T Li and YQ Fu and ZS Zhang and JY Wua, JOURNAL OF MOLECULAR LIQUIDS, 347, 118391 (2022).

DOI: 10.1016/j.molliq.2021.118391

Clathrate hydrate (CH) structures find diversely promising applications such as gas and energy storage and transport, carbon capture and storage, gas separation, water desalination, and food and pharmaceutical engineering. However, the influence of guest molecules on their properties remains largely uncharacterized. Here, the critical roles of monoatomic guest size and interaction strength with water molecule in the structural and mechanical stability of clathrate hydrates are explicitly examined by classical molecular dynamics simulations. With increasing guest size or its interaction strength, the lattice constant and mechanical properties such as Young's modulus, tensile strength, Poisson's ratio of CHs vary nonlinearly. Based on the characteristics of the contour map of lattice constant, four regions of lattice constant of CHs can be divided. Interestingly, there are crossovers in the iso- lattice constant lines and tensile strength. Upon uniaxial tension, CH destabilizes via brittle or ductile failure, relying on the size and interaction strength of monoatomic guest. The guest size and interaction strength dependent properties can be critically understood by radial distribution function, cage volume and distribution of guest@cages. (C) 2021 Elsevier B.V. All rights reserved.

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