Facile non-lithographic route to highly aligned silica nanopatterns using unidirectionally aligned polystyrene-block-polydimethylsiloxane films

ABSTRACT Thin films (monolayer and bilayer) of cylinder forming polystyrene‐block‐polydimethylsiloxane (PS‐b‐PDMS) were shear aligned by the swelling and deswelling of a crosslinked PDMS pad that was physically adhered to the film during solvent vapor annealing. The nanostructures formed by self‐assembly were exposed to ultraviolet‐ozone to partially oxidize the PDMS, followed by calcination in air at 500 °C. In this process, the PS segments were fully decomposed, while the PDMS yielded silica nanostructures. The highly aligned PDMS cylinders were thus deposited as silica nanolines on the silicon substrate. Using a bilayer film, the center‐to‐center distance of these features were effectively halved from 38 to 19 nm. Similarly, by sequential shear‐alignment of two distinct layers, a rhombic array of silica nanolines was fabricated. This methodology provides a facile route to fabricating complex topographically patterned nanostructures. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1058–1064 In this work, shear from deswelling of a PDMS pad during solvent vapor annealing and shear is applied to obtain macroscopically aligns cylindrical domains of monolayer and bilayer poly(styrene‐block‐dimethysiloxane) (PS‐b‐PDMS) films. Subsequent UV‐ozone and calcination treatment produces topographically patterned silica lines with a center‐to‐center distance of 38 nm and 19 nm for the monolayer and bilayer, respectively. The center‐to‐center distance is decreased for the bilayer due to the deposition of silica lines from both the lower and upper layers onto the substrate. Rhombic silica nanoarrays are fabricated by sequential alignment and calcination of two distinct PS‐b‐PDMS monolayers.