Thin Film Morphologies of Bulk-Gyroid Polystyrene-block-Polydimethylsiloxane under Solvent Vapor Annealing

Thin film morphologies of a 75.5 kg/mol polystyrene-block-polydimethylsiloxane (PS-PDMS) diblock copolymer (SD75) subject to solvent vapor annealing are described. Thin films were spin-cast from 1{\%} solution of SD75 in cyclohexane and annealed in cosolvent vapors consisting of mixed toluene and heptane vapors. The PS-PDMS has a double-gyroid morphology in bulk, but as a thin film the morphology consists of spheres, cylinders, perforated lamellae or gyroids, depending on the film thickness, its commensurability with the microdomain period, and the ratio of toluene:heptane vapors used for the solvent annealing process. The morphologies are described by self-consistent field theory simulations. Thin film structures with excellent long-range order were produced, which are promising for nano patterning applications.