Structure and Dynamics of Propylene Oxide and Trimethylene Oxide Clathrate Hydrates

ABSTRACTWe present results from studies of the structure and dynamics of clathrate hydrates of three cyclic ethers by neutron diffraction and preliminary results on molecular dynamics simulations. Recent results from neutron powder diffraction and quasielastic neutron scattering of studies of propylene oxide (PO, C3H6O) and its isomer trimethyelene oxide (TMO, C3H6O), are compared with structural results obtained previously for tetrahydrofuran (THF, C3H5O). Experimental evidence of distortions of the host structures with temperature is discussed in light of the findings from quasielastic neutron scattering, which indicate distinct regions of high-temperature and low-temperature rotational dynamics and a temperature dependence related to the size of the guest. Preliminary MD results indicate a general expansion of the lattice with temperature resulting in increased volume available to PO.