Microdomain Orientation of Diblock Copolymer Ultrathin Films Solvent Annealed at Low Temperatures.

The effect of temperature during solvent annealing on the microdomain orientation of block copolymer ultrathin films was investigated using symmetric polystyrene-block-poly(methyl methacrylate) diblock copolymers. When acetone solvent annealing was performed at low temperatures, 2 °C, 38% of samples exhibited a pattern of cylinders perpendicular to the substrate, while 62% of the samples exhibited a mixture of cylinders orientated parallel and perpendicular to the substrate. In the case of acetone solvent annealing at room temperature, only 6% of samples exhibited a pattern with cylinders perpendicular to the substrate, while 73% of the samples exhibited a mixture of cylinders orientated parallel and perpendicular to the substrate. We discuss how the morphology is affected by temperature during solvent annealing. The low-temperature method was used to pattern cylinders perpendicular to the substrate using PS-b-PMMA copolymers with molecular weight ranging from 52 000 g/mol per block to 160 000 g/mol per block. [ABSTRACT FROM AUTHOR]