Quasi-crystal gyroid thin films from unidirectionally aligned block copolymers through shear-rolling process
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초록
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Gyroid crystals can be utilized in various fields, including photonic crystals and optical metamaterials. For these applications, highly ordered single-grain gyroid crystals are necessary. In this work, we fabricated directed self-assembly of a shear-rolling process and sequential solvent annealing to obtain quasi-crystal gyroid block copolymer (BCP) thin films. Firstly, cylindrical nanodomains of polystyrene-block-polydimethylsiloxane (PS-b-PDMS) in thin films were unidirectionally aligned by a shear-rolling process which provide large-scale shear within a short time. Temperature and shear rate can tune orientational orders and pattern periods. Next, unidirectionally aligned cylinders transformed into the gyroid structure using solvent vapor annealing with a neutral top coat. The gyroid structures were oriented in the same direction from unidirectionally aligned cylinders, realizing long-range order like quasi-crystal structures.