Influence of Solvent Vapor Atmospheres to the Self-assembly of Poly(styrene-b-dimethylsiloxane)

Self-assembly process of poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) was investigated by using the solvent-annealing with acetone, hexane and dimethylforamide (DMF) vapor. Solvent-annealing with hexane vapor yielded a mixture of cylindrical and spherical microdomains. Acetone and DMF vapors yielded well-oriented arrays of PDMS sphere dots with 17 nm in pitch. Voronoi analysis was applied to these self-assembled patterns and revealed that the quality of the ordering of acetone and DMF were 92% and 99%, respectively. DMF was a superior solvent for self-assembly of PS-b-PDMS for the application to the bit-patterned magnetic recording media (BPM). Self-assembled dot pattern with 12 nm-pitch, which is equivalent to 5 Tb/in(2), is also demonstrated with N-methylpyrrolidone solvent vapor annealing. One of the important factors to align the PDMS sphere dots of the PS-b-PDMS by solvent-annealing is the miscibility of the solvent to the majority polymer.