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

Chen, Q., University of Minnesota
Siepmann, J. I., University of Minnesota
Lodge, T. P., University of Minnesota
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.