(45a) Quantifying Polymer and Additive Density Distributions in Ion-Conducting and Tapered Block Polymer Thin Films
AIChE Annual Meeting
2018
2018 AIChE Annual Meeting
Materials Engineering and Sciences Division
Polymer Thin Films, Nanoconfinement, and Interfaces
Sunday, October 28, 2018 - 3:30pm to 4:00pm
Block polymer (BP) electrolytes offer an enhanced balance of performance and stability for next-generation lithium-ion batteries, but to develop these technologies further, it is essential to understand both the overall self-assembly behavior and the distinct salt and polymer distributions within the specific nanoscale domains. To this end, we have quantitatively examined the lithium salt and polymer distributions in salt-doped polystyrene-b-poly(oligo-oxyethylene methacrylate) [PS-POEM] BPs and explored how the presence of salt affects BP chain conformations and thermodynamics. With respect to the lithium salt distribution, neutron reflectometry was leveraged to infer the salt distributions in POEM domains for a series of lithium salts. All salt-doped BP specimens exhibited lithium salt distributions that were strongly correlated with the POEM density profiles. Furthermore, using X-ray reflectometry in combination with strong-segregation theory, we estimated effective Flory-Huggins interaction parameters (Ïeff) and the POEM statistical segment lengths (bPOEM) as a function of salt concentration and rationalized the noted trends in Ïeff and bPOEM in terms of lithium counterion basicity.