Interpreting Neutron Reflectivity Profiles of Diblock Copolymer Nanocomposite Thin Films Using Hybrid Particle-Field Simulations

Mixtures of block copolymers and nanoparticles (block copolymer nanocomposites) are known to microphase separate into a plethora of microstructures, depending on the composition, length scale, and nature of interactions among its different constituents. Confining these nanocomposites in thin films yields an even larger array of structures, which are not normally observed in the bulk. In contrast to the bulk, exploring various microstructures in thin films by the experimental route remains a challenging task. In this work, we present a modeling scheme using the hybrid particle-field simulation approach based on a coarse-grained model for representing polymer chains by continuous curves and coupling fictitious dynamics of nanoparticles to the thermodynamic forces. The simulation approach is general enough to predict microphase separation in thin films of any block copolymer nanocomposite with the specific details encoded in the interaction parameters. The approach is benchmarked by comparisons with the depth profiles obtained from the neutron reflectivity experiments for symmetric poly(deuterated styrene-b-n-butyl methacrylate) copolymers blended with spherical magnetite nanoparticles covered by hydrogenated poly(styrene) corona. We show that the hybrid particle-field approach is an accurate way to model and extract quantitative information about the physical parameters in the block copolymer nanocomposites. This work benchmarks the application of the hybrid particle-field model to derive the interaction parameters for exploring different microstructures in thin films containing block copolymer nanocomposites.