Thermodynamic and Morphological Behavior of Block Copolymer Blends with Thermal Polymer Additivesby Sunday, Daniel F.; Hannon, Adam F.;Tein, Summer; Kline, R. Joseph
Block copolymer (BCP) blends offer a facile route toward customizable nanomaterials. To better understand these systems, the thermodynamics of polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) and poly(vinylphenol) (PVPH) blends were examined using scattering measurements and self-consistent field theory (SCFT). PVPH hydrogen bonds to the PMMA block, resulting in the selective infusion into the PMMA layer. Measurements on initially disordered blends show that this interaction can induce an order disorder transition (ODT). The ODT was observed to be a continuous transition, unlike the first-order thermal ODT typically observed in BCPs. Free energy curves extracted from SCFT simulations also observed a lack of a discontinuity in the first-order derivative. Lamellar systems underwent a greater increase in BCP period compared to identical athermal systems due to the extension of the PMMA chains away from the interface. Comparison with the SCFT models finds good agreement in the predicted behavior of the blends using a negative chi parameter to model interactions between PVPH and PMMA, including the predicted distribution of the PVPH throughout the PMMA layer.