Phase Transitions of Polystyrene-b-poly(dimethylsiloxane) in Solvents of Varying Selectivity

A simple method to create a variety of nanostructures via the self-assembly of a single composition silicon-containing block copolymer (BCP) is developed. By using selective solvents for the self-assembly of polystyrene-block-poly(dimethylsiloxane) (PS-PDMS), the phase behavior of intrinsic BCP can be enriched due to the strong segregation of the PS-PDMS enabling the diversity of the phase behavior of PS-PDMS/solvent mixtures and clear-cut phase transitions upon solvent evaporation. The solution-state phase behaviors of the strong segregation BCP system in different solvents are systematically studied using temperature-resolved and time-resolved SAXS experiments. A variety of phases, such as sphere, cylinder, gyroid, lamellar phases and even inverted phases, can be acquired by simply tuning the selectivity of solvent for casting. Meanwhile, owing to the high etching contrast of the silicon-containing block versus the PS block, various nanostructured SiOC can be fabricated by using one-step oxidation. This approach suggests an easy way to create inorganic oxide nanostructures for various applications.