(121g) The Effect of Host Miscibility and Polarity Contrast in Polymer Blend Electrolytes
AIChE Annual Meeting
Monday, November 11, 2019 - 1:42pm to 1:54pm
Motivated by these results, we sought to investigate through molecular simulation whether such a deviation can occur in polymer blend electrolytes whose hosts have some intrinsic contrast in polarity and mobility and whether this deviation is influenced by host miscibility. However, unlike small molecule electrolytes, the phase stability of polymer blends is highly sensitive to interactions between each component, including those brought on by contrast in the polarity of each polymer. Further, it is challenging to ascertain a priori from an atomistic model the extent to which two polymer components are compatible in a blend.
Thus, we chose to examine this question using a coarse-grained molecular dynamics framework. Our coarse-grained model represents all polymers as a string of coarse-grained, bead-like repeat units in each of which is embedded a freely rotating point dipole. In addition to easily tuning host polarity contrast by independently varying the strength of the dipole moment in each of the polymers, the miscibility of each polymer can easily be changed by varying the strength of hard-core interactions. This model thus allows us to vary polarity contrast independently from the compatibility of the host polymers.
Using this model, we found that increasing host compatibility can indeed lead to improvements of the ionic conductivity relative to a simple linear mixing rule, depending on polarity contrast. We investigated the underlying electrolyte properties, such as ionic aggregation and polymer dynamics, and correlated them with ionic transport in both miscible and immiscible blends.