Controlled Ordering of Block Copolymer Gyroid Thin Films by Solvent Annealing

Abstract

This work presents an approach to achieve controlled ordering of polystyrene-block-poly(l-lactide) (PS–PLLA) gyroid thin films on a neutral substrate using solvent annealing. Interesting morphological evolution from gyroid to cylinder can be found while using a partially selective solvent for the PS block to anneal the PS–PLLA thin film. To acquire a thin-film sample with thermodynamically stable gyroid morphology, a nonpreferential solvent should be used for solvent annealing to enable controlled ordering of gyroid thin film with the (211)G plane parallel to the air surface and also the functionalized substrate. By taking advantage of degradable character of the PLLA block, nanoporous PS with well-defined texture can be fabricated by hydrolysis and used as a template for synthesis of various nanohybrids and nanoporous materials.