Coarse-grained molecular dynamics simulations on self-assembly of polystyrene-block-poly(2-Vinylpyridine)

Self-assembly of block copolymers (BCPs) is highly intricate and is adsorbing extensive experimental and simulation efforts to reveal it for maximizing structural order and device performances. The coarse-grained (CG) molecular dynamics (MD) simulation offers a microscopic angle to view the self-assembly of BCPs. Although some molecular details are sacrificed during CG processes, this method exhibits remarkable computational efficiency. In this study, a comprehensive CG model for polystyrene-block-poly(2-vinylpyridine), PS-b-P2VP, one of the most extensively studied BCPs for its high Flory-Huggins interaction parameter, is constructed, with parameters optimized using target values derived from all-atom MD simulations. The CG model precisely coincides with various classical self-assembling morphologies observed in experimental studies, matching the theoretical phase diagrams. Moreover, the conformational asymmetry of the experimental phase diagram is also clearly revealed by our simulation results, and the phase boundaries obtained from simulations are highly consistent with experimental results. The CG model is expected to extend to simulate the self-assembly behaviors of other BCPs in addition to PS-b-P2VP, thus increasing understanding of the microphase separation of BCPs from the molecular level.