Characterizing the Equation of State of Polydimethylsiloxane

Generating rigorous and benchmarked equations of state (EOS) of elements and molecular systems is important for accurately modeling HED experiments and planetary interiors. Significant work exists in mapping the EOS of water, H2, NH3, CO, and CH4. However, there are few experiments exploring multicomponent mixtures of these constituents in the HED regime. We set out to explore a key multicomponent mixture to test both ab initio models and linear mixing procedures. We recently obtained EOS and X-Ray Diffraction (XRD) data of one of these key multicomponent mixtures, polydimethylsiloxane (PDMS), using laser driven shock and ramp compression at OMEGA EP. PDMS is a polymer with a roughly 1:1 ratio of components that are analogs for a rock and ice mixture in an ice giant planet. In this work, we present some preliminary Hugoniot points of PDMS from ~300-800 GPa and ~3.5-3 g/cc. Analyses are ongoing to determine the state of the sample and to explore possible nanocrystalline formation that may occur at HED conditions. This material is based upon work supported by the Department of Energy [National Nuclear Security Administration] University of Rochester "National Inertial Confinement Fusion Program" under Award Number(s) DE-NA0004144. Funding for this research was also provided by the Center for Matter at Atomic Pressures (CMAP), a