Computer simulation of PEO/layered-silicate nanocomposites:: 2.: Lithium dynamics in PEO/Li+ montmorillonite intercalates

Molecular dynamics simulations are used to explore poly(ethylene oxide)/Li+ complexes, comparing bulk and nanoscopically confined systems. We focus on lithium ion dynamics, so as to elucidate the molecular mechanisms of ionic motion in these two environments. The confined systems mimic 0.8 nm thin intercalates between mica-type layers (montmorillonite). Simulations of the Li+/bulk PEO system show a clear change in the ion transport mechanism from a hopping fashion, at low temperatures, to a random Brownian-like diffusion, at higher temperatures. In sharp contrast, the intercalated, nanoconfined, systems display a single hopping mechanism throughout the same temperature range, dictated by the unique nature of the lithium coordination to the mica-type surfaces and the confined PEO.