An Investigation of Segmental Dynamics of Poly(pentyl malonate) Electrolytes

In this study we investigated the effect of added salt on the segmental dynamics of a novel polymer electrolyte. Our system of interest is poly(pentyl malonate) (PPM) with added LiTFSI salt. We created a series of PPM/LiTFSI mixtures, with salt concentrations from 0 ≤ r ≤ 0.10 (where r is the ratio of the moles of lithium to moles of oxygen in the polymer backbone) and measured the segmental dynamics using quasielastic neutron scattering (QENS). QENS data can be used to determine segmental dynamics on length scales ranging from 3 to 60 Å and on the nanosecond timescale, well-suited to probing polymer electrolyte dynamics. Assuming the Rouse model, we calculated the monomeric friction coefficient from QENS experiments and found that the friction coefficient increases exponentially with increasing salt concentration. We examine the relationship between the friction coefficient and ion transport in this polymer electrolyte system and compare these results to a previously studied polymer electrolyte system: poly(ethylene oxide) (PEO) with added LITFSI salt.