(200c) Predicting the Binary Interaction Parameter Chi for Polymer Pairs from Oligomer Simulations

The binary interaction parameter chi plays a crucial role in predicting the phase behavior and thus materials properties of polymer blends and block copolymers. However, the determination of the chi parameter is not assumption-free. Current methods to estimate the chi parameter from theory, experiment, and simulation often involve the random-phase approximation. In this work, configurational-biased Monte Carlo simulations using the TraPPE-UA force field are performed to directly compute the free energy of mixing for a variety of oligomer blends. Extrapolation of these data to infinite-chain length allows to predict chi parameters, solubility parameters, and mixing irregularities. In addition, structural analysis from the simulation provides further insight into the mixing behavior of these blends.