Mechanical stability of fluorinated-methane clathrate hydrates

Clathrate hydrates recently find important practical applications in the capture and recovery of green-house gases, cold storage and refrigeration systems. Nevertheless, their properties at microscopic scale remains largely insufficient yet. Herein, the structure and stability of clathrate hydrates encapsulating fluorinated methane derivatives under mechanical load are investigated by molecular dynamics simula-tions. All investigated clathrate hydrates are structurally stable host-guest molecular crystals yet show distinct structural and mechanical behaviors. Lattice constant of those clathrate hydrates is dictated by the size and dipole moment of fluorinated methane, for example, it is initially enlarged with increasing fluorine atom in the methane guest molecule but followed by reduction as the guest molecule becomes tetrafluoromethane. However, clathrate hydrates encapsulating non-polar fluorinated methane show superior mechanical properties over those encapsulating polar ones. Polar fluorinated methane deriva-tives@clathrate cages exhibit distinct rotational dynamics that are influenced by strain. Moreover, all studied clathrate hydrates are mechanically failed by fractures of water cage accompanied by formation of unconventional clathrate cages. Those findings give insights into understanding the structural, thermo-dynamic stability and mechanical properties of clathrate hydrates encapsulating fluorinated guests.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the structure and stability of clathrate hydrates encapsulating fluorinated methane derivatives under mechanical load through molecular dynamics simulations. The study finds distinct structural and mechanical behaviors among different clathrate hydrates, and the lattice constant of clathrate hydrates is influenced by the size and dipole moment of the encapsulated fluorinated methane.