Two dimensional nano-dot array engineering of block copolymer surface micelles on water surface

When an amphiphilic block copolymer is directly spread from an organic solution, the morphology of the surface micelles is not in general controlled because the structure is rapidly frozen after the solvent evaporation. In contrast, we have developed a new versatile method to generate highly regular ordered nanopatterns of the surface micelles on water, which involves the process of two dimensional (2D) hybridization with a polar liquid crystal molecule, 4′-pentyl-4-cyanobiphenyl (5CB) [Langmuir 22 (2006) 5233]. The present work extends this approach using a family of diblock copolymers of polystyrene-block-poly(4-vinylpyridine) changing the chain length of the two polymer blocks. It is found here that the dot-to-dot distance and the dot size can be precisely controlled on-demand by the length of the polymer blocks. Such structural regulations cannot be attained without the 5CB hybridization. Due to the high reproducibility of the morphology formation, this process should be of practical significance to ‘engineer’ the 2D patterns in the range of some tens of nanometers.