(561a) Predicting Mixing Free Energy for Polymers with Atomistic Simulations
AIChE Annual Meeting
2022
2022 Annual Meeting
Materials Engineering and Sciences Division
Polymer Simulations: Methods and Applications
Wednesday, November 16, 2022 - 3:30pm to 3:45pm
The phase behavior of polymer blends depends on the mixing free energy of the constituents. Obtaining the mixing free energy from atomistic simulations is challenging. Our group has previously developed two approaches: 1) atomistic morphing, which requires structurally similar polymers, and 2) mutual ghosting, which can be applied to molecules of any structure, but is involved and computationally expensive. Here, we present a new generally applicable method, in which we apply equal and opposite cosine potentials to the polymers, to induce a concentration variation. Polymers with repulsive interactions will respond to the potential with a larger concentration variation; in this way, we can evaluate the interaction strength between polymers. First we test the new âpush-pullâ method on bead-spring polymer blends, with results comparable to previous approaches. Then, we investigate a challenging system: blends of P3HT donor polymers and ITDBR acceptor molecules used in organic photovoltaic (OPV) materials. The donor-acceptor interface in such materials plays a key role in exciton binding and dissociation; the interfacial width is governed by the Flory-Huggins chi parameter between donor and acceptor moieties, which we can now predict from simulations.