Solvent annealing induced perpendicular orientation of cylindrical microdomains in polystyrene-b-poly(4-hydroxyl styrene)/peg oligomer blend thin film made by spin-coating from selective solvent

Abstract

The microphase separated structure of PS-b-PHS/PEG blend thin film with thickness of 500 ∼ 600 nm was investigated by grazing incidence small angle X-ray scattering. The thin film was obtained by two different solutions; one was THF which was common good solvent for all components of polymers used here. The other is toluene which was selective solvent for PS and poor-solvent for PHS and PEG. The equilibrium morphology of the block copolymer and blend sample was hexagonally packed cylinder in the bulk and thin film. The structure in the thin film obtained by spin cast from toluene solution was non-equilibrium. After THF vopar annealing of the thin film (cast from toluene), the highly ordered and perpendicular oriented cylindrical structure was obtained. Perpendicular orientation was failure when the thin film sample made by spin cast from THF solution and subsequent THF vapor annealing. The perpendicular nano-holes were fabricated after removing PEG oligomer by washing with water. © Published under licence by IOP Publishing Ltd.